Milwaukee M18 vs DeWalt 20V Battery Inverter: Which Should You Buy?
Both an M18 and a DeWalt 20V MAX battery run a 150W inverter identically — the one that fits the batteries you already own is the right buy. Both packs operate at 18V nominal under load; a 150W load doesn't care about the badge. The only real tiebreaker: if you need more than 150W of AC, only Milwaukee M18 has options in our catalog (220W, plus a 350W pure sine). DeWalt 20V MAX tops out at 150W here. Pick the inverter that mounts to the batteries already in your bag.
| Milwaukee M18 | DeWalt 20V MAX | |
|---|---|---|
| Nominal voltage | 18V | 18V (20V max, unloaded) |
| 150W inverter available | ✓ | ✓ |
| Higher-wattage options (>150W) | ✓ (175W, 220W, 350W) | ✗ |
| Pure sine wave option | ✓ (350W model) | ✗ |
The Short Answer — Who Should Buy Which?
- Already own Milwaukee M18 tools? Get the Milwaukee M18 150W Inverter (150W) or step up the ladder if the job demands it. Don't buy a DeWalt inverter.
- Already own DeWalt 20V MAX tools? Get the DeWalt 150W Inverter (150W). Same AC output, same runtime math, different connector.
- Need more than 150W or clean power for sensitive gear? Milwaukee M18 is the only platform with a solution here — DeWalt doesn't have it in our catalog.
Are the Batteries Actually Different?
Yes and no. "20V MAX" is DeWalt's no-load marketing voltage — it's the open-circuit reading on a full lithium pack. Under any real load, both M18 and DeWalt 20V MAX packs run at 18V nominal. Milwaukee has always called theirs M18. Same chemistry, same platform voltage, different connector and branding.
That "voltage gap" people fight about on forums? It doesn't exist where it counts. A 150W inverter sees the same voltage from either pack. If you want the deeper breakdown on the two platforms, Milwaukee M18 vs DeWalt 20V comparison covers it in full.
What *does* differ: the physical battery interface. An M18 inverter is built around the M18 tab; a DeWalt inverter is built around the 20V/FLEXVOLT slide rail. They don't swap. We'll cover that below.
Head-to-Head: The Two 150W Inverters
Both the M18 150W and the DeWalt 150W deliver one AC outlet, USB-A ports, and a clip-on battery mount. At a continuous 150W, either one handles a phone charger, a small battery charger, an LED work light, or a laptop without issue. The spec comparison at this tier is short because there isn't much to separate them.
| Milwaukee M18 150W Inverter | DeWalt 150W Inverter | |
|---|---|---|
| Continuous AC output | 150W | 150W |
| Battery fit | M18 only | 20V MAX / FLEXVOLT only |
| USB-A ports | Yes | Yes |
| Waveform | Modified sine | Modified sine |
Wondering if 150W is actually enough for your job? Is 150W enough for power tools walks through what you can and can't run at that rating.
At this wattage tier, the inverter decision is about platform fit, not specs. Buy the one that mounts to your batteries.
Where Milwaukee Pulls Ahead — More Inverter Options
Here's the honest catalog reality: Milwaukee M18 has a full wattage ladder. DeWalt doesn't.
Milwaukee M18 inverter lineup:
- 150W — Milwaukee M18 150W Inverter — single AC outlet, USB-A, clip-on
- 175W (genuine Milwaukee TOP-OFF) — Milwaukee M18 TOP-OFF 175W Power Supply — three-device charging station, made by Milwaukee, zero compatibility questions
- 220W with 30W USB-C PD — 220W M18 Inverter with USB-C PD — AC outlet plus USB-C fast charge plus USB-A simultaneously
- 220–250W — 220–250W Milwaukee M18 Inverter — extra headroom for heavier loads
- 350W pure sine — 350W Pure Sine M18 Inverter — for sensitive electronics; see the next section
DeWalt 20V MAX inverter lineup:
- 150W — DeWalt 150W Inverter — single AC outlet, USB-A
That's the full list. No 220W, no pure sine. If you need more than 150W of AC from a battery pack and you're on DeWalt, Milwaukee M18 is the only platform here that solves the problem.
At 150W the two platforms are completely even. Above 150W, Milwaukee wins by default — not because the battery is better, but because the accessory catalog is deeper.
How Long Will Each Run?
Runtime is math, not brand loyalty. Every battery is a watt-hour reservoir. Bigger Ah = bigger reservoir. The inverter drains it at a fixed rate, minus roughly 10–15% in conversion losses (assume ~85% efficiency — this is an estimate based on typical inverter specs, not a published figure for these specific units).
Formula: Usable Wh = Ah × 18V × 0.85 ÷ load watts = hours
| Battery | Ah | Usable Wh (est. ~85%) | At 150W | At 100W |
|---|---|---|---|---|
| M18 XC5.0 | 5.0 | ~77 Wh | ~31 min | ~46 min |
| M18 HIGH OUTPUT XC6.0 | 6.0 | ~92 Wh | ~37 min | ~55 min |
| M18 FORGE HD12.0 | 12.0 | ~184 Wh | ~73 min | ~110 min |
| DeWalt FLEXVOLT 12.0Ah | 12.0 | ~184 Wh | ~73 min | ~110 min |
The FLEXVOLT 12.0Ah runs at 18V nominal in 20V MAX mode, so the math holds the same as the M18 HD12.0. A big battery is a big battery, regardless of color.
If you're running sustained loads — a charger, a fan, a radio — pair your inverter with the largest Ah pack you carry. The compact 2.0Ah and 3.0Ah packs aren't the right tool for this. For a longer breakdown of runtime scenarios, How long will a battery run an inverter has the full worked examples.
Pure Sine vs Modified Sine — Does It Matter for Your Gear?
Both 150W inverters output modified sine wave power. So do the 220W M18 units. Modified sine is fine for the vast majority of site loads:
- Cordless battery chargers (Milwaukee, DeWalt, your phone)
- LED work lights and flood lights
- Small fans and heaters
- Most laptop brick chargers
Where modified sine causes problems: sensitive electronics — audio/video gear, some older MacBook power bricks, certain medical devices, and some variable-speed motor tools that run hotter or noisier on modified power.
If any of that describes your load, the 350W Pure Sine M18 Inverter is the only pure sine option in our catalog — and it's M18-only. DeWalt 20V has no pure sine equivalent here.
For most contractors running a phone, a radio, and a battery charger off a site inverter, modified sine is the right and cheaper call. Look for "requires pure sine" in your device documentation. Most don't have it. For a deeper explanation of when the waveform actually matters, Pure sine vs modified sine waveforms covers it without the jargon.
Compatibility First — Will It Fit YOUR Battery?
There is no safe adapter that bridges an M18 battery to a DeWalt inverter, or vice versa. Don't try it. The battery rail geometry, communication protocol, and discharge management are all brand-specific. Third-party adapters that claim cross-brand compatibility bypass the battery's built-in protection circuit. That's not a trade-off worth making.
Hard rules:
- Milwaukee M18 inverter → M18 batteries only (XC, HIGH OUTPUT, FORGE — all Ah ratings)
- DeWalt 150W inverter → 20V MAX and FLEXVOLT batteries only
- Neither works on M12, 12V MAX, or the other brand's packs
The Power tool battery compatibility breakdown has the full cross-platform compatibility picture if you're running tools from multiple brands on the same site.
Which Should You Buy?
| Your situation | Best pick |
|---|---|
| Own Milwaukee M18 tools | Milwaukee M18 150W Inverter (150W), or up the ladder |
| Own DeWalt 20V MAX tools | DeWalt 150W Inverter (150W) |
| Own both platforms | Whichever brand has your highest-Ah pack — more Wh = more runtime |
| Need more than 150W AC | M18 only — 220W M18 Inverter with USB-C PD or the 220–250W |
| Need clean power for sensitive electronics | 350W Pure Sine M18 Inverter (M18 only) |
| Just need to charge a phone and run a light | Either 150W works — pick your platform and move on |
There's no scenario where switching platforms for an inverter makes sense. The inverter follows the batteries; the batteries follow the tools you already own.
Frequently Asked Questions
Is the Milwaukee M18 inverter better than the DeWalt 20V one? At 150W they perform the same — same AC output, same runtime from equivalent Ah packs. M18 wins only if you need higher wattage or pure sine, which DeWalt doesn't offer here. Same job, same load, equivalent batteries? Pick either.
Can I use a DeWalt battery on a Milwaukee M18 inverter — or the other way around? No. Battery interfaces are brand-specific and physically incompatible. There's no approved adapter. Third-party adapters bypass battery protection circuits — not worth the risk.
How many watts do the Milwaukee M18 inverters put out? Our M18 options run 150W, 175W (TOP-OFF), 220W (two variants — one with 30W USB-C PD), and 350W pure sine. For the heaviest site loads, the M18 CARRY-ON (model 2845-20) delivers 1,800 watts continuous.
Does DeWalt make a higher-watt inverter than 150W? Not in our catalog. If you need more AC output and run DeWalt, you'll need to manage load on the 150W unit — or you're looking at Milwaukee M18.
How long will a battery run an inverter? Roughly: Ah × 18 × 0.85 ÷ load watts = runtime in hours. A 5.0Ah M18 pack at 150W continuous runs about 30 minutes. A 12.0Ah FORGE or FLEXVOLT pack at the same draw gets you around 73 minutes. Drop the load, stretch the runtime.
Is the Milwaukee inverter pure sine wave? The 350W M18 model is pure sine. The 150W, 175W, 220W, and 220–250W units are modified sine — fine for most tools, chargers, lights, and heaters.
Can you run power tools off a battery inverter? Yes, within the wattage limit — but check the startup surge, not just the running watts. A circular saw may draw 300–400W at startup even if it runs steady at 180W. A 150W inverter trips on that. Check the tool's nameplate; if surge exceeds the inverter's peak rating, step up to the 220W or 350W M18 option.
Once you match the inverter to the load and the battery on your platform, running AC power from a job site pack is genuinely useful — not a gimmick. Most site uses stay well under 150W. The bigger M18 options are there when they're not.
Browse the full Milwaukee platform range if you're on M18, or the DeWalt platform range if you're on DeWalt. The right inverter is already in your platform.