Are Milwaukee Batteries Interchangeable? M12, M18, Other Brands

Milwaukee batteries are interchangeable across Milwaukee tools of the same system, but not with other brands. Milwaukee's own pages talk about M12, M18 and MX FUEL as separate systems, warn against third-party batteries and chargers, and say nothing about crossing over to Makita, DeWalt or Ryobi. This guide sticks to what Milwaukee actually states, shows what a mismatched pack costs you, and explains where adapters and aftermarket packs fit in.

Best Milwaukee M18 Battery to Buy

If you already run M18 tools, a 5.0 Ah pack is a sensible all-round spare. Milwaukee's M18 page states that all M18 batteries are compatible with M18 tools and chargers, so you can move a pack between a drill, a saw and a light without checking model numbers. We have not tested the pack ourselves, so the compatibility claims here come from Milwaukee, and prices come from the Amazon listing we checked on September 30, 2026. If you are weighing bigger packs, see our Milwaukee 9.0 Ah battery guide.

What Milwaukee Says About Compatibility

We read Milwaukee's M18 battery and charger page, its REDLITHIUM battery selection guide and a current M18 product page. The message is consistent: compatibility is promised inside a system, and it stops at the system boundary.

Milwaukee page	What it says
M18 batteries and chargers page	All M18 batteries are compatible with M18 tools and chargers
M18 batteries and chargers page	All M12 batteries are compatible with M12 tools and chargers
M18 batteries and chargers page	Authentic M18 batteries must be charged on Milwaukee M18 chargers; do not use third-party batteries or chargers
Battery selection guide	M12 tools use M12 packs (12V), M18 tools use M18 packs (18V), MX FUEL tools use MX FUEL packs (72V)
Battery selection guide	Batteries are designed to be backward and forward compatible within their own power tool system
M18 FORGE XC6.0 product page	Works with 300+ tools and all M18 chargers

Two things stand out. First, Milwaukee never lists another brand as a compatible battery source. Second, the simplest test Milwaukee gives is to match the label on the tool: an M18 tool wants an M18 pack.

M12, M18 and MX FUEL: Three Separate Battery Families

Most “are Milwaukee batteries interchangeable” searches are really about Milwaukee to Milwaukee. The three families do not mix in the tool, even though they share a name and a red-and-black look.

System	Battery voltage	Tools it runs (per Milwaukee)	Cross-system use
M12	12V	M12 tools	Not listed as compatible with M18 or MX FUEL tools
M18	18V	M18 tools, 300+ per the FORGE XC6.0 page	Not listed as compatible with M12 or MX FUEL tools
MX FUEL	72V	MX FUEL tools	Not listed as compatible with M12 or M18 tools

One wrinkle: some Milwaukee chargers accept more than one pack type. Milwaukee's catalog includes an M18 and M12 four bay super charger, and a multi-voltage charger that takes both M12 and M18 packs is sold on Amazon. That is convenient, but it only means one charger serves two Milwaukee systems. It does not mean an M12 pack will run an M18 tool. For the pack-by-pack answer, see Can you use M18 batteries on M12 tools? and M12 vs M18.

Old and New M18 Batteries: The Backward Compatibility Question

Several searches ask whether a new Milwaukee battery works on a previous-generation tool. Milwaukee's battery guide says that whether you bought a battery today, five years ago or five years from now, it will work with any Milwaukee cordless tool in the same system. That is a strong statement, but it covers the system generations the guide describes (REDLITHIUM era M12, M18 and MX FUEL).

Milwaukee's pages that we read do not discuss much older nickel-cadmium 18V packs from before the M18 line, so we cannot confirm from Milwaukee whether a modern pack fits an old drill. If you own a much older Milwaukee tool, check the label on both the tool and the pack, and check the manual before you try to force a fit.

There is also a naming trap. Milwaukee's battery guide sorts packs into three types (CP compact, XC extended capacity and HD high demand) across three technology tiers (REDLITHIUM, REDLITHIUM HIGH OUTPUT and REDLITHIUM FORGE). As far as we can tell from that guide, “FUEL” is not one of the battery tiers, so a search for a “FUEL battery” usually points at a REDLITHIUM pack sold with a FUEL-branded tool kit. We did not verify what FUEL branding covers, so confirm it on the product page before you buy.

M18 pack listed by Milwaukee	Capacity	Milwaukee-listed charge time	Tier
XC5.0	5.0 Ah	60 min	REDLITHIUM
XC6.0 FORGE	6.0 Ah	25 min	FORGE
XC8.0 HIGH OUTPUT	8.0 Ah	45 min	HIGH OUTPUT
HD12.0 HIGH OUTPUT	12.0 Ah	60 min	HIGH OUTPUT

Charge times are the figures on Milwaukee's M18 battery page, and they depend on the charger used, so treat them as a guide. The point for compatibility is that every row is an M18 pack: a bigger number changes runtime and price, not which tools the pack fits.

Milwaukee Batteries and Other Brands: What Each Match-Up Looks Like

The table below reflects what Milwaukee states, not what we tested. Where a row says “no statement,” that means we found no Milwaukee page saying the pack works in that brand's tools, and we are not claiming to know how the other brand's system is built.

Brand or tool	Does Milwaukee say its pack fits?	Where to read more
Makita, DeWalt	No statement; only unofficial adapters exist	Adapter section below
Ryobi, RIDGID	No statement (they share a parent company with Milwaukee, but that does not make packs interchangeable)	RIDGID battery guide and Do Ryobi batteries fit other brands?
Bosch 12V	No statement	Bosch and Milwaukee 12V batteries
Bauer	No statement	Milwaukee batteries on Bauer tools
Craftsman, Metabo, Hercules	No statement	Match the label, then check that brand's own pages

On ownership: Wikipedia reports that Techtronic Industries (TTI) bought Milwaukee Electric Tool from Atlas Copco in 2005 and had earlier acquired Ryobi's North American power tool business in 2000. Shared ownership does not make the packs cross-compatible, and we found no source saying they are. For a wider view across brands, see our cordless battery compatibility chart and the DeWalt 20V battery guide.

Battery Adapters: What They Do and Why We Do Not Recommend Them

Adapters that let a Milwaukee pack power a Makita or DeWalt tool (and the reverse) are sold by third parties. According to How-To Geek's review of adapters, they typically pass raw power to the tool rather than letting the tool and battery communicate, which bypasses the protection that manufacturers build into a matched system. That article lists possible results such as motor damage, overheating, a melted adapter and battery wear, says the warranty is likely to be affected, and its author concludes adapters are not worth the risk. Milwaukee's own product page describes REDLINK as full-system communication between tool, battery and charger that prevents overloads, which is exactly the link an adapter cuts.

That is a press opinion plus a manufacturer feature description, not a lab test, and some people report using adapters for light jobs without trouble. We have not tested any adapter. If you still choose to use one, keep it to light-duty work, never charge through it, and stop if the pack, adapter or tool gets hot.

Genuine vs Third-Party Milwaukee Batteries: The Cost Per Amp-Hour

The reason people ask about aftermarket packs is price. On September 30, 2026 we pulled current Amazon listings for a few M18-format packs. The per-Ah figures below are simple division of listed price by listed capacity, and the third-party capacity is the seller's claim.

Pack (Amazon listing)	Listed price	Listed capacity	Price per Ah
Milwaukee 48-11-1820 REDLITHIUM 2.0 Ah compact	$36.94	2.0 Ah	$18.47
Milwaukee 48-11-1850 REDLITHIUM XC5.0	$69.09	5.0 Ah	$13.82
Third-party 2-pack, sold as M18-compatible 5.0 Ah	$53.99	2 x 5.0 Ah (seller claim)	$5.40

The gap is large, but so are the unknowns. Third-party packs do not carry Milwaukee's compatibility statement, and Milwaukee says to avoid third-party batteries and chargers. A pack that fits physically has not been shown to communicate correctly with your tool or charger. Note also that the genuine price per Ah falls as capacity rises: the XC5.0 at $13.82 per Ah beats the 2.0 Ah at $18.47.

How to Check Before You Plug a Battery In

• Read the system label on the tool: M12, M18 or MX FUEL. Buy the same system.
• Look for the Milwaukee name and the system logo on the pack. Physical fit alone does not prove compatibility.
• Charge only on a Milwaukee charger listed for that pack, as Milwaukee advises.
• Pick capacity for the job: a compact CP pack for light drilling, an XC or HD pack for saws and long sessions.
• Treat adapters and aftermarket packs as untested, and never leave one charging unattended.
• If a pack swells, leaks, smells or runs unusually hot, stop using it and take it to a battery recycling location.

Frequently Asked Questions About Milwaukee Battery Compatibility

Are Milwaukee batteries interchangeable with other brands?

No. Milwaukee’s own pages describe its batteries, tools and chargers as systems (M12, M18 and MX FUEL), and we found no Milwaukee statement that its packs work in another brand’s tools. Milwaukee also tells users not to use third-party batteries or chargers with its M18 packs.

Can you use a Milwaukee battery in Makita or DeWalt tools?

Milwaukee does not say you can. Third-party adapters exist that physically connect one brand’s pack to another brand’s tool, but they send raw power without the tool-to-battery communication Milwaukee’s REDLINK system provides, and no manufacturer we checked endorses them. We do not recommend them and have not tested any.

Are all Milwaukee batteries and chargers interchangeable?

Within one system, yes, according to Milwaukee. Its battery guide says its batteries are designed to be backward and forward compatible within the dedicated system, so an M18 pack bought years ago should work with a newer M18 tool. M12, M18 and MX FUEL packs stay in their own systems.

Can a Milwaukee charger charge other brands’ batteries?

We would not try it. Milwaukee says authentic M18 batteries must be charged on Milwaukee M18 chargers, and its pages do not describe charging other brands’ packs. Some Milwaukee chargers accept both M12 and M18 packs, but that is one brand’s two systems, not a cross-brand feature.

Are third-party replacement Milwaukee batteries safe?

We cannot say from testing, because we do not test batteries. Milwaukee advises against third-party batteries and chargers, and capacity ratings on aftermarket packs are the seller’s claims. If you use one, buy from a seller with a return policy and stop using any pack that overheats, swells or smells.

Conclusion

Milwaukee batteries interchange across Milwaukee tools of the same system, and Milwaukee says older and newer packs in a system work together. They are not interchangeable with other brands, M12, M18 and MX FUEL do not mix in the tool, and Milwaukee advises against third-party packs and chargers. Match the system label, use a Milwaukee charger, and treat adapters and aftermarket batteries as untested claims rather than proven compatibility.