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FLEX 24V 6 1/2-Inch Inline Circular Saw Review FX2131A-1C

Flex 24V Inline Circular Saw Puts its Skinny Belt On

Flex broke into the professional cordless power tool sector with an impressive list of first-generation tools. While many of them check the boxes for core tools every Pro needs, the Flex 24V 6 1/2-Inch Inline Circular Saw is something completely different.


  • Comfortable ergonomics
  • Impressive cutting speed
  • Significantly improved sightline on the right
  • Cutting depth of a 7 1/4-inch saw
  • Vacuum hose adapter included
  • 5-year warranty (extended to lifetime with registration by 12/31/21)


Flex 24V Inline Circular Saw Performance

First of all, yes, this is a VERY different design. We’ll take a closer look at that in a minute. For now, let’s start with performance. After all, if it can’t cut, who cares about the design?

We put this circular saw to the test in our shop and did our best to push it to the limits. Along with a series of test cuts, we ran it through the PTR Circular Saw Test Track.

Test Track Parameters

If you’re not familiar with the setup, here’s what this Test Track entails:

  • Cross cutting: five cross cuts (2 x 10)
  • Bevel cutting: five 45º bevel cross cuts (2 x 10)
  • Miter cutting: five 45º miter cuts (2 x 10)
  • Compound cutting: three 45º miter/45º bevel compound cuts from each side of the lumber (6 cuts total, 2 x 10)
  • Power drive: one 4-foot rip cut (double-stacked 3/4-inch OSB subfloor)
Flex 24V Inline Circular Saw

The saw clearly isn’t as strong as Flex’s standard-design 7 1/4-inch saw, but it’s no slouch, either. It finished with a time of 2:10, well behind its 7 1/4-inch counterpart at 1:36. When you look at the saws that finished ahead of the inline model, they’re all using bigger batteries to get the extra muscle. Against saws that stick with more traditional single batteries, it competes with the best.

The good thing is that it was able to complete all of our cuts with a high degree of confidence. You’ll need to slow down a little to let the RPMs stay high on bevel and compound cuts, but there’s nothing that we’re cutting with 7 1/4-inch saws that we’d shy away from.

Bevel Cut

Flex 24V Inline Circular Saw Design Notes

Consequences of an Inline Design

We really like the idea of an inline circular saw. It almost feels like a rear-handle saw when you’re cutting but with some major mechanical differences. The slim profile houses a sensor-free brushless motor that powers the saw’s unusual belt drive.

Flex 24V Inline Circular Saw Front Profile

That belt drive doesn’t just make a difference in the feel of the cut, but also with its depth. With its 6 1/2-inch blade, this saw has an impressive cutting depth of 2 9/16-inches—the same as many of the 7 1/4-inch saws we use and enough to cut 3x in one pass.

Aside from the depth of cut, the shoe is drastically slimmer than other designs. It has the typical left-side sightline for a blade-left saw, but the right side is significantly better. It’s the closest thing to a circular saw that meets both preferences we’ve seen.

Right Side Blade View

One thing to note is that the bevel range maxes out at 47°. This isn’t the only saw to have that limit, but with many reaching 56°, it’s worth pointing out.

Flex 24V Inline Circular Saw Bevel Adjust

Despite having a compact design, don’t confuse this saw as having a DIY target. It feels built to handle the jobsite environment as well as most of the Pro brands we use.

Size and Weight

With its smaller size, we expect the saw to weigh less than a full-size model and it does. Bare, the tool weighs 7.1 pounds and a 5.0Ah battery brings that up to 9.1 pounds. Anything less than 10 pounds is solid for a cordless saw, though it’s not quite as light as some of our other 6 1/2-inch models.

Flex 24V Inline Circular Saw Profile

The main handle fits very well in my medium hands and the secondary handle is a good size. It’s a little close to the main handle compared to a full-size saw, but that’s what we expect from a compact design.


With a 5.0Ah battery, the overall balance is spot on.

Additional Features

  • Foldable rafter hook
  • Built-in hex key storage
  • LED work light
  • Vacuum-hose adapter
  • Compatible with the entire Flex 24V system

FLEX 24V Inline Circular Saw Price

Flex prices this saw at $249.00 and is available at Lowe’s. It comes with the saw, a 5.0Ah battery, 160W fast charger, blade, and carry bag. At the time we’re writing, there’s no bare tool option.

Flex tools carry a 5-year warranty. If you register your tools by 12/31/21, they’ll extend it to a lifetime warranty.

The Bottom Line

Flex found a way to give you excellent visibility from both sides of the blade and give a 6 1/2-inch circular saw the cutting capacity of a 7 1/4-inch saw. No other circular saw we’ve tested can make that claim and it has the performance to compete at the top of the compact class. If you’re looking for a cordless compact circular saw, none offer a better overall package than the Flex 24V 6 1/2-inch inline circular saw.

Flex 24V Inline Circular Saw Specifications

  • Model: Flex FX2131A-1C
  • Blade Size: 6-1/2 in
  • No-Load Speed: 5,500 RPM
  • Bevel Capacity: 0-47°
  • Arbor: 5/8 in
  • Cut Capacity at 90°: 2-9/16 in
  • Cut Capacity at 45°: 1-9/16 in
  • Tool Weight (bare): 7.1 lbs
  • Tool Weight (with 5Ah battery): 9.4 lbs
  • Price: $249 with 5.0Ah battery, fast charger, blade, and bag
  • Warranty: 5 years (lifetime with registration by 12/31/21

For more information on the full FLEX 24V lineup, click here

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