A cordless impact wrench is selected by three numbers: the square drive it carries, the maximum torque it can deliver, and the bolt size it is rated to turn. Everything else — motor type, battery capacity, housing material — follows from those three.
This page sets out how the three fit together, and where each model in the M7 cordless range sits.
In this article
- What a cordless impact wrench is, and what it is not
- Three questions that decide the tool
- Drive size: 3/8 in., 1/2 in. and 3/4 in.
- Reading the torque figure on a spec sheet
- The M7 cordless impact wrench range
- The 18V battery platform
- Where cordless fits alongside air
- Sources and specification notes
- Frequently Asked Questions
What a cordless impact wrench is, and what it is not
A cordless impact wrench is a battery-powered tool that drives a square anvil with rotational hammer blows, so it can loosen and tighten nuts and bolts that a steady-torque tool would stall on. The impacts are what let a compact tool break a joint that has been torqued down or corroded in place.
Two tools are regularly confused with it, and the difference matters when you are specifying:
- Impact driver — hex collet, not a square drive. Built for fasteners and screws, not for wheel nuts or structural bolts.
- Torque wrench — a measuring instrument. An impact wrench delivers torque; it does not measure the torque it has applied. Final torque on a safety-critical joint is set with a torque wrench, not with an impact wrench.
M7 also builds a torque-limited version, the DW-405, which caps output at a set level rather than measuring it. That is a different job again, and it is covered in the range table below.
Three questions that decide the tool
Tool selection has no single right answer, so work backwards from the job rather than forwards from the catalogue. Three questions settle most of it.
What are you turning?
Start with the fastener, not the tool. Bolt capacity — the M-number in the spec table — is the figure that tells you whether a tool is rated for the joint at all. A tool rated M6 to M16 is not the tool for an M24 structural bolt, whatever its headline torque figure says.
How long is it running each day?
Continuous work and occasional work call for different classes of machine. A tool that changes four wheels a day and a tool that runs all shift in a fleet workshop will not wear at the same rate, and the heavier tool is heavier for a reason.
What is already on site?
If there is a compressor with adequate pressure and hose diameter, air tools stay competitive on sustained output. If there is no air supply — roadside service, structural work at height, mobile fleet maintenance — the question answers itself.
Drive size: 3/8 in., 1/2 in. and 3/4 in.
Drive size is the first thing to fix, because it sets the ceiling on everything else. The M7 cordless range covers three sizes.
| Square drive | Torque available in the M7 range | Typical work | M7 models |
|---|---|---|---|
| 3/8 in. (9.5 mm) | 434 Nm / 320 ft-lb | Engine bay, interior trim, confined access, light assembly | DS-204 |
| 1/2 in. (12.7 mm) | 894–1700 Nm / 660–1250 ft-lb | Passenger-car wheel nuts, general automotive, maintenance work | DW-401, DW-404, DW-404K, DW-405, DW-IW400, DW-C401, DW-406, DW-402 |
| 3/4 in. (19 mm) | 1900 Nm / 1400 ft-lb | Commercial vehicle wheels, heavy plant, structural fasteners | DW-601 |
A larger drive is not automatically the better buy. A 3/4 in. tool weighs roughly three times what a compact 1/2 in. tool weighs, and that weight is carried by the operator all day. Size the drive to the largest fastener you actually turn, not to the largest you can imagine turning.
Reading the torque figure on a spec sheet
Maximum torque is a laboratory figure, measured under controlled conditions. It tells you what the tool is capable of, not what it will produce on a corroded joint at the end of a battery charge.
Three things to check alongside it:
- Bolt capacity — the practical rating. It is the number that says which fasteners the tool is designed for.
- Speed settings — most M7 models offer three or four no-load speeds. Lower settings exist so that you can control a joint, not just break it.
- Impact rate — blows per minute. A high impact rate at moderate torque loosens a stubborn joint differently from a single high-torque setting.
Final torque on wheel nuts and any safety-critical joint is set with a torque wrench. An impact wrench gets the fastener seated; it does not certify the value.
The M7 cordless impact wrench range
All figures below are reproduced from the official M7 product pages, verified on 26 August 2026. Every model number links to the product page the figures came from. Where a value is not published on the datasheet, the cell is marked with a dash rather than estimated.
| Model | Square drive | Max. torque | Bolt capacity | No-load speed (rpm) | Impact rate (ipm) | Weight |
|---|---|---|---|---|---|---|
| DS-204 | 3/8 in. / 9.5 mm | 434 Nm / 320 ft-lb | M5–M8 screw; nut 8–13 mm | — | — | 1 kg bare |
| DW-401 | 1/2 in. / 12.7 mm | 894 Nm / 660 ft-lb | M16; nut 24 mm | 0–1100 / 0–1600 / 0–2200 | 0–1500 / 0–2500 / 0–3000 | 1.48 kg |
| DW-404 | 1/2 in. / 12.7 mm | 900 Nm / 660 ft-lb | M6–M16; nut 10–24 mm | 0–900 / 0–1400 / 0–1800 / 0–2200 | 0–1150 / 0–1700 / 0–2300 / 0–2500 | 1.16 kg |
| DW-404K | 1/2 in. / 12.7 mm | 900 Nm / 660 ft-lb | M6–M16; nut 10–24 mm | 0–900 / 0–1400 / 0–1800 / 0–2200 | 0–1150 / 0–1700 / 0–2300 / 0–2500 | 1.16 kg |
| DW-405 | 1/2 in. / 12.7 mm | 900 Nm / 660 ft-lb | M6–M16 | 1200 / 1750 / 2300 / 2800 | — | 1.2 kg |
| DW-IW400 | 1/2 in. / 12.7 mm | 900 Nm | M6–M16 | 0–1000 / 0–1700 / 0–2400 | 0–2300 / 0–2800 / 0–3100 | 1.3 kg |
| DW-C401 | 1/2 in. / 12.7 mm | 1350 Nm | M6–M26 | 0–1100 / 0–1700 / 0–2200 | 0–1100 / 0–2200 / 0–3300 | 1.7 kg |
| DW-406 | 1/2 in. / 12.7 mm | 1600 Nm / 1200 ft-lb | M10–M25; nut 17–36 mm | 0–1400 / 0–1900 / 0–2400 | 0–1800 / 0–2200 / 0–2800 | 2.0 kg bare |
| DW-402 | 1/2 in. / 12.7 mm | 1700 Nm / 1250 ft-lb | M10–M24; nut 17–36 mm | 0–900 / 0–1000 / 0–1700 | 0–1800 / 0–2000 / 0–2200 | 3.33 kg |
| DW-601 | 3/4 in. / 19 mm | 1900 Nm / 1400 ft-lb | M10–M27 | 0–900 / 0–1000 / 0–1800 | 0–1800 / 0–2000 / 0–2200 | 3.37 kg |
Three models are worth calling out because they answer a specific question rather than a general one:
- DS-204 — the only 3/8 in. tool in the range, at 115 mm overall length. Where access decides the job, a shorter tool that fits beats a stronger one that does not.
- DW-405 — a brushless, torque-limited wrench. Output is capped at a set level, which is the answer when over-tightening is the risk you are managing.
- DW-C401 — 1350 Nm and M6–M26 bolt capacity at 1.7 kg and 163 mm. It is the compromise between the compact 900 Nm tools and the heavy 1/2 in. machines.
Full specifications, including overall length and kit contents, are on each product page. Model numbers should be quoted in full when ordering — DW-404 and DW-404K are separate items.
The 18V battery platform
M7 cordless impact wrenches run on a shared 18V lithium-ion platform, so batteries and chargers carry across the range rather than being tied to one tool.
Four battery capacities are listed:
- DB-1825 — 18V 2.5 Ah
- DB-401 — 18V 4.0 Ah
- DB-501 — 18V 5.0 Ah
- DB-1850P — 18V 5.0 Ah
Capacity determines working time between charges, not torque. A higher-capacity pack on a 900 Nm tool does not make it a 1200 Nm tool; it makes it a 900 Nm tool that runs longer. Where a bay is in continuous use, two packs in rotation matter more than one large one.
Tools are supplied as bare units or as kits. The kit versions include battery and charger; the bare tool assumes you already have packs on the platform.
Where cordless fits alongside air
Cordless has taken over the work where the air line was the constraint rather than the tool: roadside service, mobile fleet maintenance, work at height, and any site where running hose is more trouble than the job is worth.
Air still holds an advantage in sustained duty cycles in a fixed bay with an adequate compressor, where a tool runs continuously and weight at the handle is lower without a battery on board. M7 builds both, so the honest answer is that the two overlap rather than one replacing the other.
The deciding factors are usually the ones nobody puts on a spec sheet: whether the compressor keeps up at the pressure the tool is rated for, what hose diameter is actually installed, and how far the work is from the air supply.
Sources and specification notes
Every figure on this page comes from M7’s own published product documentation. Nothing has been converted, rounded or estimated from a comparable model.
- Source — the official product page for each model on mighty-seven.com. Each model number in the range table links to the page its figures were taken from.
- Specifications verified — 26 August 2026. Where M7 revises a datasheet, the product page is the current record and this page is updated against it.
- Dual units — Nm and ft-lb are shown together only where both are printed on the datasheet. Where only one unit is published, only that unit appears; a converted figure is not the manufacturer’s figure.
- Dashes in the table — the value is not published on that model’s datasheet. A dash means “not published”, not “zero” and not “unknown to us”.
- Maximum torque — a laboratory measurement under controlled conditions, published for comparison between models. It is not a working figure for a specific joint.
- Final torque — set with a calibrated torque wrench to the vehicle or structure manufacturer’s specified value. No figure on this page is a substitute for that specification.
For full datasheets, kit contents and models not listed here, request the current M7 catalogue or ask your local distributor.
Frequently Asked Questions
What size cordless impact wrench do I need for lug nuts?
For passenger-car wheel nuts, a 1/2 in. drive tool is the standard choice, and every 1/2 in. model in the M7 range is rated at 894 Nm or above. For commercial vehicle wheels, move to the 3/4 in. DW-601 at 1900 Nm / 1400 ft-lb. Check the vehicle manufacturer’s specified torque and set the final value with a torque wrench.
What does brushless mean on an impact wrench?
A brushless motor uses electronic commutation instead of carbon brushes, which removes a wearing part and the friction that comes with it. In practice that means less heat, no brush replacement, and more of the battery’s energy reaching the anvil. The M7 DW-405 is a brushless, torque-limited model.
Can a cordless impact wrench replace an air impact wrench?
For most mobile and intermittent work, yes — the M7 cordless range reaches 1900 Nm, which covers the joints an air tool is normally brought in for. In a fixed bay with a compressor sized for continuous duty, air remains competitive on sustained output and handle weight. The choice depends on the site, not on the tool class.
What is the difference between bolt capacity and maximum torque?
Maximum torque is the peak output measured under laboratory conditions; bolt capacity is the fastener range the tool is designed to work on. Bolt capacity is the more useful number when specifying, because it accounts for the joint rather than the tool. Both are published for every M7 model.
Are impact wrench and impact driver the same thing?
No. An impact wrench has a square drive and takes impact sockets, for nuts and bolts. An impact driver has a hex collet and takes bits, for screws and fasteners. They are not interchangeable for wheel or structural work.
Contact us, or talk to your local distributor
![[Recommended Reciprocating Saw] M7 Cordless Reciprocating Saw DRS-102A Review: The Best Lightweight and Efficient Choice](https://i0.wp.com/tools.mighty-seven.com/wp-content/uploads/2024/10/2-2.jpg?fit=300%2C300&ssl=1 "[Recommended Reciprocating Saw] M7 Cordless Reciprocating Saw DRS-102 Review: The Best Lightweight and Efficient Choice 6")
