Milwaukee M12 Fuel Circular Saw Gen 2 Model 2521

Milwaukee M12 Fuel 5 3/8-inch Circular Saw 2521

Milwaukee is launching an updated M12 Fuel 5 3/8-inch circular saw with a couple of real “wow” factors built in. I actually did a double take when I saw Milwaukee refer to the 2521 as just the second-generation model considering I wrote about the first-generation 2530 way back in 2015.

It’s hard to believe in such a fast-changing world that a cordless saw—especially a 12V model—could have a 9-year run. For those of us who have used that saw, it’s not such a surprise. That said, battery and motor technology has improved tremendously over that time, so I’ll share what to look for in the new model and help you decide if you should upgrade.

Milwaukee M12 Fuel Circular Saw Updates

Milwaukee M12 Fuel 5 3/8-inch Circular Saw 2521

If you’re new to the 5 3/8-inch circular saw class, they’re the most compact models we use, but don’t accuse them of being DIY products. They still have enough cutting capacity to handle 2x lumber and sheet goods. With a more compact size and lighter weight, they’re a popular option for tradesmen who don’t need higher capacity or extreme runtime, such as remodelers.

The first area of improvement is in the saw’s performance. For starters, the blade speed jumps by 250 RPM, topping out at 3850 RPM.

In addition to the higher speed, you can also expect an increase in power. Between the latest M12 Fuel PowerState brushless motor and the relatively recent expansion of M12 5.0Ah High Output batteries, the saw can ask for more power and the battery is capable of delivering it.

The other big deal is a significant reduction in weight. The first-generation 2530 weighed 5.3 pounds. The new 2521 drops all the way down to 4.7 pounds (both are bare tool weights). Losing over half a pound on a compact tool makes it even easier to work with.

If that isn’t enough, the second-generation saw is also even more compact. At 10.9 inches long, it’s nearly 1.5 inches shorter than the previous model 2530.

Milwaukee M12 Fuel Circular Saw 2530 vs 2521 Quick Comparison

2530 (Gen 1)2521 (Gen 2)
No-Load Speed3600 RPM3850 RPM
Blade Size5-3/8 or 5-1/2 in.5-3/8 or 5-1/2 in.
Bare Weight5.3 lbs4.7 lbs
Length12.4 in10.9 in

Milwaukee M12 Fuel Circular Saw Price

As a bare tool, the saw is $159. The kit includes a 5.0Ah High Output battery and is $259. Both options are only $10 more than the previous version, meaning these impressive upgrades aren’t going to cost much more to take advantage of.

The tool is backed by a 5-year warranty.

Look for both options to hit your favorite Milwaukee retailer in May 2024.

Is There a 6 1/2-inch Circular Saw in the Future?

With the higher performance, I wondered if we might see an M12 Fuel 6 1/2-inch circular saw at Pipeline in the next year or two. It’s an interesting question, and I think the answer is… not yet.

With the improvements in the battery and motor, I believe the M12 system already has the available power to make a 6 1/2-inch saw work well. However, runtime is still an issue. The 5.0Ah High Output battery has the same capacity as an M18 3.0Ah battery—54 watt-hours. While you certainly could get some work done, most Pros rely on low-capacity batteries as a backup option rather than a primary one for circular saws.

Then there’s the payoff. By moving to a 6 1/2-inch blade, you’re gaining the cut capacity for 45° cuts in 2x lumber which the 5 3/8-inch blade can’t complete. While that would be a convenient upgrade, it’s a tougher cut, further reducing the number of cuts you can make on a charge.

I think we’ll need to see another big jump in brushless motor efficiency to make the runtime more relevant before we see an M12 Fuel 6 1/2-inch model. Never say never, though. Milwaukee’s design teams are typically thinking several years ahead on product development and they frequently surprise us with what they’re ready to launch.


  • Model: 2521
  • Power Source: M12 RedLithium Battery Pack (High Output recommended)
  • Blade Size: 5-3/8 or 5-1/2 inches
  • Arbor: 10mm
  • No Load Speed: 3850 RPM
  • Bare Weight: 4.7 pounds
  • Warranty: 5 years

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