Is a 40W laser engraver really 40 watts?

It depends what the 40 W measures. Most current diode machines from major brands state optical output, and owners who measured them with a power meter reported readings close to the claim. Some listings have used electrical input instead: Atomstack’s X70 Max is now named a 70 W machine, but its product URL still says “360W”, a figure search extracts of the maker page give as its electrical input. CO2 tube ratings often do not say what they measure at all.

What is the difference between optical power and input power?

Optical power is the light that leaves the laser and reaches the work. Input power is the electricity the machine draws from the wall, which is several times higher because the laser module, motors, fans and controller are not 100 % efficient. Only optical power belongs in a settings conversion.

Does a smaller spot really matter if the watts are the same?

Yes. Power density — watts divided by the spot area — sets how hot the material gets under the beam. Two 20 W diodes with spots of 0.08 × 0.10 mm and 0.12 × 0.18 mm differ by more than two times in power density. Compare density only between lasers of the same type, because diode, CO2 and fiber light is absorbed differently.

How can I measure my laser’s real power?

With a laser power meter or a calorimetric probe such as the Mahoney probe that many CO2 owners use. Measure at full power, note where you measured (CO2 owners often measure after the first mirror) and repeat a few shots, because readings vary. Check the meter’s maximum rating: one popular hobby review site uses a 50 W meter, so readings near 50 W are at its limit.

Machine data

What the watts on the box really mean

The number in a laser’s name is not always the power of its beam. Here are 35 recent machines with the headline watts, the optical output the maker states for each laser, the spot size and the power density — and what owners measured with power meters.

The table

Headline watts vs optical output

In each row, the outlined bar is the number in the name and the filled bar is the optical output the maker states for the main laser, drawn to the same scale; a hatched bar means the maker does not state it. Dual-laser machines list their second laser in the Lasers column. Filter to the 5 machines whose headline is electrical input or not stated as anything, or sort by power density.

Machine	Headline vs optical	Lasers	Spot & power density	Work area	Enclosure & class	Maker’s cut claim
xTool S1 40W checked on maker page Note Air assist is a separate accessory. The 20W version lists 498 x 330 mm, so the work area differs slightly by module.	40 Woptical main laser, optical 40 W	Diode 455 nm · 40 W	0.08 × 0.1 mm 6,366 W/mm² main laser	498 × 319	Enclosed Class 1 (Class 4 with riser base + conveyor feeder)	Wood 18 mm cherry, one pass Acrylic 15 mm dark opaque acrylic, one pass
xTool F1 checked on maker page Note Dual laser: 10 W blue diode + 2 W 1064 nm IR (IR spot 0.03 x 0.03 mm). Fold-down shield, and xTool itself calls it Class 4. Black acrylic is 6 mm in one xTool page and 5 mm in another, so it is left out. Power adapter is 24 V 5 A.	10 Woptical main laser, optical 10 W	Diode 445±15 nm · 10 W IR 1,064±5 nm · 2 W	0.08 × 0.06 mm 2,653 W/mm² main laser	115 × 115	Galvo with shield Class 4	Wood 8 mm wood (passes not stated)
xTool F1 Ultra checked on maker page Note Dual laser: 20 W diode + 20 W fiber (fiber spot 0.03 x 0.03 mm). Input current is 10 A in one user guide and 8 A in the EU guide, so input is left out.	20 Woptical main laser, optical 20 W	Diode 445±15 nm · 20 W Fiber 1,064±5 nm · 20 W	0.08 × 0.1 mm 3,183 W/mm² main laser	220 × 220	Enclosed Class 1 (MXF-K002-001) or Class 4 (MXF-K002-B20), by model number	Wood 12 mm basswood (passes not stated) Acrylic 12 mm black acrylic (passes not stated)
xTool F2 checked on maker page Note Dual laser: 15 W diode + 5 W IR, stated as average power. One xTool goggle table lists the F2 as 10 W, but the FAQ and the safety page both say 15 W. The IR engraves metal but does not cut it. 115 x 400 mm with the slide extension.	15 Woptical main laser, optical 15 W	Diode 445±15 nm · 15 W IR 1,064±5 nm · 5 W	—	115 × 115	Galvo with shield Class 4	Wood 15 mm basswood, multiple passes Acrylic 12 mm acrylic, multiple passes
xTool F2 Ultra (dual) checked on maker page Note Dual laser: 60 W MOPA fiber (2-500 ns, 30-4000 kHz) + 40 W diode. xTool does not say whether the 40 W diode is one emitter or combined beams. A 400 W input figure exists only on a retailer page, so it is left out.	60 Woptical main laser, optical 60 W	Diode 445±15 nm · 40 W MOPA fiber 1,064±5 nm · 60 W · pulsed	—	220 × 220	Enclosed Class 4	Wood 23 mm wood (passes not stated) Acrylic 20 mm acrylic (colour and passes not stated)
xTool F2 Ultra UV checked on maker page Note The user guide says 5 W and one goggle table says 5.5 W max. A thick-wood claim for a 5 W UV source is unusual, so treat it as the maker's claim only. Inner (subsurface) area 70 x 70 mm.	5 Woptical main laser, optical 5 W	UV 355±5 nm · 5 W	—	200 × 200	Enclosed Class 4 (MXF-K007-002) or Class 1 (MXF-K007-001), by model number	Wood 15 mm wood, "lab-tested max" (passes not stated) Acrylic 12 mm acrylic (passes not stated)
xTool P2S 55W checked on maker page Note xTool states 55 W as the maximum laser power. A built-in air pump (up to 200 kPa) is included.	55 Woptical main laser, optical 55 W	CO2 10,600 nm · 55 W	—	600 × 305	Enclosed Class 1 or Class 4 version	Wood 18 mm basswood, one pass Acrylic 20 mm acrylic, one pass (colour not stated)
Atomstack A24 Ultra (X24 Ultra in the EU) search extract of maker page Note 24 W = four 6 W diodes combined; one spec block gives 20-24 W. 120 W is machine power. Both maker URLs showed the A20 Pro V2 on 2026-10-27, so the A24 Ultra may no longer be sold new. Spot (0.06 x 0.06 vs 0.06 x 0.08) and cut claims disagree between Atomstack pages.	24 Woptical, beams combined main laser, optical 24 W	Diode 455±5 nm · 24 W	—	365 × 305	Open frame	—
Atomstack X70 Max (A70 Max) search extract of maker page Note The current title says 70W. The product URL and older titles say "360W", which search extracts of the maker page give as electrical input (not re-read). Optical output is 70-77 W in 70 W mode and 35-39 W in 35 W mode (spot 0.08 x 0.12 mm). Cut claims differ between the X70 and A70 pages (25 vs 26 mm acrylic, 30 mm pine vs 28 mm), so they are left out. Shown as sold out on 2026-10-27.	70 Woptical main laser, optical 70 W	Diode 455±5 nm · 70 W	0.12 × 0.18 mm	850 × 800	Open frame	—
Atomstack A40 Pro V2 search extract of maker page Note The product page (read) says only "48W/24W Diode switching"; "48W optical power" is from a search extract. Older A40/X40 Pro titles say "210W", which looks like electrical input but no Atomstack page confirms it. Cut claims disagree (18 mm wood in the listing, 20 mm basswood in a review summary).	48 Woptical main laser, optical 48 W	Diode · 48 W	0.08 × 0.1 mm	385 × 400	Open frame	—
Atomstack P1 Dual (5W + 1.2W IR) search extract of maker page Note The page (read) confirms "5W Diode + 1.2W IR"; the other values are search extracts. IR spot 0.03 x 0.03 mm, IR area 105 x 100 mm. A plain P1 without the IR module is also sold.	5 Woptical main laser, optical 5 W	Diode 455 nm · 5 W IR 1,064±1 nm · 1.2 W	0.08 × 0.06 mm	110 × 110	Enclosed Class 1	Wood 3 mm basswood plywood, one pass Acrylic 3 mm black acrylic, multiple passes
Sculpfun S30 Ultra 33W checked on maker page Note Sculpfun writes "this is light energy not electrical energy" next to 33 W, and lists machine power separately (about 156 W). Goggles, a laser shield and a 30 L/min air pump are in the box. The product page gives no cut thickness.	33 Woptical main laser, optical 33 W	Diode 455±5 nm · 33 W	0.08 × 0.1 mm 5,252 W/mm² main laser	590 × 595	Open frame	—
Sculpfun S30 Pro Max 20W checked on maker page Note Stated as optical ("light energy not electrical energy"); machine power about 120 W. Goggles and a detachable protection cover are included. No cut thickness on the product page.	20 Woptical main laser, optical 20 W	Diode 455±5 nm · 20 W	0.08 × 0.1 mm 3,183 W/mm² main laser	370 × 360	Open frame	—
Sculpfun A9 Ultra (40W diode + 20W fiber) checked on maker page Note Dual laser. Diode spot 0.1 / 0.15 mm (switchable 40/20 W); fiber spot 0.05 mm on the US page but 0.01 mm on the EU page. Fiber cuts thin metal (0.3-0.4 mm stainless per the FAQ).	40 Woptical main laser, optical 40 W	Diode 455 nm · 40 W Fiber 1,064 nm · 20 W	—	400 × 400	Open frame Class 4	Wood 30 mm wood, one pass Acrylic 30 mm black acrylic, "at once"
Ortur Laser Master 3 10W (LU2-10A) checked on maker page Note Ortur gives the optical output as 9,500-10,500 mW. A review hosted on ortur.net says the LU2-10A combines two 5.5 W diodes ("compressed spot"). Ortur cut claims for this module range from 8 mm plywood to 12 mm wood in one pass, so they are left out. 24 V 4 A adapter.	10 Woptical main laser, optical 10 W	Diode 445±5 nm · 10 W	0.05 × 0.1 mm 2,546 W/mm² main laser	400 × 400	Open frame	—
Creality Falcon2 22W checked on maker page Note 22 W optical from four 6 W diodes combined. 120 W is maximum machine power. Product-page marketing says "15mm wood / 10mm acrylic"; the maker's own parameter table is used here.	22 Woptical, beams combined main laser, optical 22 W	Diode 455±5 nm · 22 W	0.08 × 0.1 mm 3,501 W/mm² main laser	400 × 415	Open frame Class 4 (FDA Class IV)	Wood 10 mm basswood, one pass at 100%, 120 mm/min (maker parameter table) Acrylic 4.6 mm black acrylic, one pass; 7.6 mm in two passes (maker parameter table)
Creality Falcon2 40W checked on maker page Note 40 W from eight diodes combined (Creality pages disagree on 5 W or 5.5 W per diode). 240 W machine power and the work area are search extracts. Spot is 0.08 x 0.12 mm in the parameter guide but 0.1 / 0.15 mm on the product page, so it is left out. Marketing says "20mm wood one pass".	40 Woptical, beams combined main laser, optical 40 W	Diode 455±5 nm · 40 W	—	400 × 415	Open frame	Wood 15 mm basswood, one pass at 100%, 150 mm/min (maker parameter table) Acrylic 4.6 mm black acrylic, one pass; 7.6 mm in two passes (maker parameter table)
Creality Falcon A1 10W checked on maker page Note "Dual laser" on the A1 means two blue beams combined into one spot (Creality blog), not a second wavelength. Spot and 120 W machine power are search extracts. Regional Creality stores give 6 mm and 12 mm wood, so cut claims are left out.	10 Woptical, beams combined main laser, optical 10 W	Diode · 10 W	0.06 × 0.08 mm 2,653 W/mm² main laser	381 × 305	Enclosed Class 1 (FDA)	—
Creality Falcon A1 Pro 20W (+2W IR) checked on maker page Note Dual laser: 20 W diode + 2 W IR (IR spot 0.03 mm). The 2 W IR module is sold separately or in bundles. Diode wavelength, diode spot and laser class are search extracts.	20 Woptical main laser, optical 20 W	Diode 455±5 nm · 20 W IR 1,064±1 nm · 2 W	0.08 × 0.1 mm 3,183 W/mm² main laser	358 × 268	Enclosed Class 1 (FDA)	Wood 10 mm basswood (passes not stated on the page) Acrylic 8 mm black acrylic (passes not stated on the page)
LaserPecker LP4 checked on maker page Note Dual laser: 10 W 450 nm diode + 2 W 1064 nm pulsed IR. Spots (IR 0.05 x 0.05 mm) are from a maker comparison table seen as a search extract. Another LaserPecker page says 8 mm basswood. 160 x 300 mm with the slide extension; laser class is not stated.	10 Woptical main laser, optical 10 W	Diode 450 nm · 10 W IR 1,064 nm · 2 W · pulsed	0.08 × 0.1 mm 1,592 W/mm² main laser	160 × 120	Galvo with shield	Wood 8 mm balsa (product page) Acrylic 5 mm dark opaque acrylic
LaserPecker LP5 checked on maker page Note Dual laser: 20 W diode + 20 W fiber (fiber spot 0.06 x 0.06 mm). Area is a 120 x 160 mm ellipse or 100 x 100 mm square. Only the LP5 Safeguard (fully enclosed) is marketed as Class 1; the safety enclosure is sold separately.	20 Woptical main laser, optical 20 W	Diode 450 nm · 20 W Fiber 1,064 nm · 20 W	0.08 × 0.1 mm 3,183 W/mm² main laser	120 × 160	Galvo with shield	Wood up to 20 mm basswood (passes not stated) Acrylic up to 15 mm black acrylic (passes not stated)
Bambu Lab H2D Laser Module 10W search extract of maker page Note Bambu states 10 W +/- 1 W. The module also carries an 850 nm laser used only for height measuring. Plywood is 5 mm on the tech-specs page but 6 mm on the store page, so it is left out. Also fits the H2S and H2C.	10 Woptical main laser, optical 10 W	Diode 455±5 nm · 10 W	0.03 × 0.14 mm	310 × 270	Enclosed Module Class 4, whole system Class 1	—
Bambu Lab H2D Laser Module 40W search extract of maker page Note Bambu states 40 W +/- 2 W. Not supported on the H2S (H2D and H2C only). A 15 mm black-acrylic figure appears only in retailer copies of the store table, so it is left out.	40 Woptical main laser, optical 40 W	Diode 455±5 nm · 40 W	0.14 × 0.2 mm	310 × 250	Enclosed Module Class 4, whole system Class 1	Wood 15 mm basswood plywood (passes not stated)
Glowforge Aura checked on maker page Note Cutting area 12 x 12 in with a passthrough. Glowforge gives one general maximum cut, not per material.	6 Woptical main laser, optical 6 W	Diode 450 nm · 6 W	—	305 × 305	Enclosed Class 1 (embedded Class 4 laser)	Wood up to 1/4 in (6 mm), material not stated
Glowforge Pro (45W CO2) checked on maker page Note Glowforge lists "45w" for the CO2 glass tube without saying it is measured optical output. 800 W is the peak power on an older spec page. Area is about 11 x 19.5 in on one page and "20 by 12" on another, so it is left out. Glowforge restructured in late 2025 and still sells. Community readings of the older 40 W Basic are in POWER_REPORTS.	45 Wnot stated what it is optical not stated	CO2 10,600 nm	—	—	Enclosed Class 4	—
OMTech Polar 50W search extract of maker page Note 50 W is the glass-tube rating ("rated"); optical output is not stated. 600 W is power consumption (OMTech manual, read on manualslib). The manual says Class 4 even though the machine is enclosed. A "10 mm max cut" figure could not be tied to a specific OMTech page, so it is left out.	50 Wnot stated what it is optical not stated	CO2 10,600 nm	—	510 × 300	Enclosed Class 4	—
OMTech K40+ search extract of maker page Note OMTech calls the same 720 mm glass tube "45W" on one page and "40W" on others; optical output is not stated. 8 x 12 in bed. See the K40 community reading in POWER_REPORTS.	45 Wnot stated what it is optical not stated	CO2	—	300 × 200	Enclosed	—
Monport 40W CO2 (12 x 8 in, K40 class) search extract of maker page Note The page (read) shows only the title "40W CO2 Laser Engraver (K40)". The 10 mm figure on Monport pages is marking depth, not a cut. Optical output and laser class are not stated.	40 Wnot stated what it is optical not stated	CO2	—	300 × 200	Enclosed	—
Gweike G2 20W fiber checked on maker page Note Stated as "Output Power 20W" (ytterbium fiber, 20-200 kHz). Gweike does not say whether it is Q-switched or MOPA. Power consumption is stated as under 120 W. 150 x 150 mm field with the other lens. A metal marker, not a wood or acrylic cutter.	20 Woptical main laser, optical 20 W	Fiber 1,064 nm · 20 W · pulsed	—	110 × 110	Open frame	—
Thunder Laser Bolt 30W checked on maker page Note 30 W SPT RF (metal) CO2 tube, not glass. Thunder does not state optical output or cut thickness. The Bolt Plus 24 in the same series uses a 60 W RF tube on 610 x 407 mm.	30 Wnot stated what it is optical not stated	CO2	—	508 × 305	Enclosed FDA Class 1	—
TwoTrees TTS-55 Pro checked on maker page Note TwoTrees lists 5.5 W laser power and 41 W overall power. Some retailer titles call it a "40W" engraver, which is close to the overall power, not the laser. A TwoTrees material-test page (search extract) shows "tested 4.98W". Area is 300 x 300 mm in the spec table but 600 x 500 mm in the feature list, so it is left out.	6 Woptical main laser, optical 5.5 W	Diode · 5.5 W	0.08 × 0.08 mm 1,094 W/mm² main laser	—	Open frame	—
Longer Ray5 20W search extract of maker page Note Named 20W, but the maker page title (search extract) says "22-24W output" from a quad-diode module, so the optical figure is left open. Work area (400 x 365 vs 375 x 375 mm) and cut claims (15 mm to 25 mm pine) disagree.	20 Woptical optical not stated	Diode	0.08 × 0.1 mm	—	Open frame	—
NEJE Max 4 V2 + E80 module checked on maker page Note The product page states "24W constant optical power". "E80" is the model name; a search extract of the module listing ties it to about 80 W electrical input (not re-read). NEJE's purchase guide calls the E80 a 20 W module. Air assist is not included.	24 Woptical main laser, optical 24 W	Diode · 24 W	0.09 × 0.09 mm 3,773 W/mm² main laser	720 × 450	Open frame	—
NEJE A40640 module checked on maker page Note A module for the NEJE Max 4 frame. The URL says "40w", but the current title says "12W Blue Diode Laser Module" and the page does not explain the 40. An earlier search extract gave "pulse 12W+, CW 11W", dual beam. Community posts call it the "80W" module (see POWER_REPORTS). Wavelength is a search extract; a 0.04 x 0.06 mm spot appears only in search extracts, so it is left out.	12 Woptical main laser, optical 12 W	Diode 455±5 nm · 12 W	—	—	Open frame	—
Genmitsu L8 40W checked on maker page Note 40 W module; total input under 240 W (the 20 W version: under 144 W, 400 x 400 mm). Built-in enclosure with camera and a 30 L/min pump. The product page gives no cut thickness.	40 Woptical main laser, optical 40 W	Diode 455 nm · 40 W	0.07 × 0.13 mm 5,597 W/mm² main laser	390 × 390	Enclosed Class 1	—

Maker values checked 2026-10-27. “Checked on maker page” means we read the headline and optical power on the maker’s own page or support site; “search extract” means the maker page could not be opened again and the values come from consistent search extracts of it. Cut claims are the maker’s, with its stated conditions — we did not test them. We read a diode laser’s “W” as optical output, as the industry does, unless the maker says it is input; a CO2 figure counts as optical only where the maker calls it output. Power density is shown only for rows checked on the maker page.

Three ways the headline number misleads

Electrical input in the name. Some diode machines have been sold under their electrical input. Atomstack’s X70 Max is now named for its 70 W of light, but its product URL still carries “360W”, which matches the input figure in search extracts of the maker page. When an older listing gives a large watt number, check whether it is the light or the power supply.
Several beams added together. Creality’s Falcon2 22W, for example, compresses four 6 W diode beams into one spot, and says so. The total is optical output, but it is a different kind of number from a single diode’s rating, and many high-watt diodes are built this way without saying so.
CO2 tubes without a stated measurement. CO2 tube ratings like “40W” or “50W” usually do not say whether they are measured optical output. Owners’ readings of CO2 tubes range widely, from about 40 % below to about 20 % above the label.

Power density: why spot size matters

Power density (W/mm²) = optical power (W) ÷ spot area (π/4 × spot length × spot width)

A laser burns by concentrating light, so the same watts in a smaller spot burn hotter and finer. The table computes density for the main laser wherever the maker states a spot size. Use it to compare machines of the same type: fiber spots are tiny and their densities huge, but metal absorbs that light differently from how wood absorbs a blue diode. To pick an engraving line interval from the spot size, use the line interval & DPI calculator; to move settings between machines, use the power & speed converter with the optical power from this table.

What owners measured

These are readings owners posted with a power meter. We have not checked them, and meters, methods and machine condition vary. For blue diode lasers rated by optical output, readings ran from −12 % to +3 % of the claim; CO2 tubes varied far more.

Machine	Claimed	Measured	vs claim	Note
K40 (stock tube) 2020-07-31	40 W (tube rating)	28 W	−30 %	Cloudray HLP-200 at 18 mA, measured after the first mirror; the stock tube was later suspected to be degraded.
OMTech "50W" CO2 tube (880 mm) 2022-12-18	50 W (tube rating)	44 W	−12 %	Mahoney probe; mA and % not stated. The same owner reported 43 W for the same tube in 2024 (counted once).
OMTech 60W CO2 2024-12-25	60 W (tube rating)	73.8 W	+23 %	HLP-200B at 90% PWM (22 mA), average of 5 shots; 71.1 W at 99%. Reads above the nameplate.
Reci 80W CO2 tube 2021-01-25	80 W (tube rating)	46 W	−43 %	Mahoney probe on an older, low-hours tube; the owner was already seeing weak cuts, so the tube may have been faulty.
Glowforge Basic (40W) 2021-11-03	40 W (tube rating)	23 W	−43 %	Mahoney probe and a digital meter agreed, straight-line job at Full power, measured where the beam enters the head.
Unnamed "40W" CO2 (not a Glowforge) 2021-11-03	40 W (tube rating)	32 W	−20 %	One-line report; meter and conditions not stated.
Thunder Laser Nova 24 2021-12-04	60 W (tube rating)	70 W	+17 %	Method not stated ("tested out at"); it may be a factory test-sheet figure.
NEJE A40640 ("80W") 2021-10-07	80 W (input)	10 W	−87 %	About 10 W; meter not stated. The 80 W in the listing was never optical output.
NEJE "30W" module 2021-10-26	30 W (input)	5 W	−83 %	Full power for 29 s; the poster called it "not scientific". NEJE's own spec for this module was 7.5 W optical.
xTool D1 Pro 20W 2023-03-20	20 W (optical)	20.5 W	+3 %	Homemade, uncalibrated calorimeter; three full-power runs gave 20.34, 20.85 and 20.53 W (earlier runs 17.9-18.4 W). The reviewer says the numbers are not validated.
xTool D1 Pro 40W 2024-03-05	40 W (optical)	38 W	−5 %	Above 40 W at the start, settled at 38 W. The meter tops out at 50 W, so it was near its limit; page date 2024, content may be older.
Sculpfun SF-A9 40W 2024-03-06	40 W (optical)	41 W	+2 %	Unnamed meter; hobbylasercutters.com's meter tops out at 50 W, so 41 W is near its limit. The 20 W setting was "spot on" (no number).
Sculpfun S30 Ultra 33W 2024-03-06	33 W (optical)	34 W	+3 %	"Almost 34W"; meter and conditions not stated.
Atomstack Maker A30 / X30 / S30 Pro 33W 2024-03-06	33 W (optical)	29 W	−12 %	One reading for the shared 33 W module; meter and conditions not stated.
Longer Laser B1 33W 2024-03-06	33 W (optical)	29 W	−12 %	Meter and conditions not stated.
Acmer P2 33W 2024-03-06	33 W (optical)	31 W	−6 %	Meter and conditions not stated.
Atomstack A70 Pro (35W mode) 2024-06-04	35 W (optical)	32 W	−9 %	"A bit more than 32W" on a 50 W-max meter. The 70 W mode could not be measured; the reviewer's 64 W is an estimate, so it is not listed.
xTool D1 2W infrared module (1064 nm) 2024-03-05	2 W (optical)	2.3 W	+15 %	Unnamed optical meter; conditions not stated.

Read cut claims with care

Maker cut-thickness claims often leave out the number of passes, the wood species and the speed, and the same maker can give different numbers in different places — one product page we read gave 6 mm of dark acrylic in one pass in one place and 30 mm of black acrylic, with no pass count, in another. The table keeps each claim with its stated conditions and leaves it out where the maker’s own pages disagree.

FAQ

Is a 40W laser engraver really 40 watts?: It depends what the 40 W measures. Most current diode machines from major brands state optical output, and owners who measured them with a power meter reported readings close to the claim. Some listings have used electrical input instead: Atomstack’s X70 Max is now named a 70 W machine, but its product URL still says “360W”, a figure search extracts of the maker page give as its electrical input. CO2 tube ratings often do not say what they measure at all.
What is the difference between optical power and input power?: Optical power is the light that leaves the laser and reaches the work. Input power is the electricity the machine draws from the wall, which is several times higher because the laser module, motors, fans and controller are not 100 % efficient. Only optical power belongs in a settings conversion.
Does a smaller spot really matter if the watts are the same?: Yes. Power density — watts divided by the spot area — sets how hot the material gets under the beam. Two 20 W diodes with spots of 0.08 × 0.10 mm and 0.12 × 0.18 mm differ by more than two times in power density. Compare density only between lasers of the same type, because diode, CO2 and fiber light is absorbed differently.
How can I measure my laser’s real power?: With a laser power meter or a calorimetric probe such as the Mahoney probe that many CO2 owners use. Measure at full power, note where you measured (CO2 owners often measure after the first mirror) and repeat a few shots, because readings vary. Check the meter’s maximum rating: one popular hobby review site uses a 50 W meter, so readings near 50 W are at its limit.

Sources

Each machine name in the table links to the maker page its values came from; each owner reading links to the original post. The full research notes, including values we left out because sources disagreed, are summarised in each machine’s note.

Last checked 2026-10-27 · No machine was tested to make this page. See also the laser safety glasses checker and diode vs CO2 vs fiber.