Can You Use a Smaller Circular Saw Blade?
This is one of the most frequently asked circular saw questions, and the answer is nuanced. Technically, a smaller blade may physically fit your saw (as long as the bore matches), but that doesn’t mean it’s safe or advisable. Here’s what actually happens, the risks involved, and the few situations where it might be acceptable.
Short Answer
Generally no. A smaller blade reduces cutting depth and can stop the guard working properly, and DeWalt’s manuals say not to use blades smaller or larger than recommended. The exception is a saw whose manual lists a minimum blade diameter: Bosch’s 190mm GKS 18V-68 GC, for example, accepts blades down to 184mm.
What Happens When You Use a Smaller Blade
When you fit a blade that’s smaller than your saw’s rated diameter, several things change:
- Reduced cutting depth — Each 10mm smaller in diameter means roughly 5mm less maximum cutting depth. A 150mm blade in a 165mm saw loses about 7-8mm of cutting depth.
- Blade guard may not function — The lower blade guard on a circular saw is designed to retract as the blade meets the workpiece. With a smaller blade, the guard may not make proper contact and could jam or fail to retract.
- Different blade speed at the rim — A smaller blade has lower rim speed at the same RPM, which can affect cut quality and increase heat build-up.
- On table saws: blade may sit below the table surface — This is the most dangerous scenario. Never use a significantly smaller blade on a table saw.
When It Might Be Acceptable
Some people fit 160mm plunge-saw blades, such as Festool’s 160mm x 20mm TS 55 blades, to 165mm saws, but makers do not support this: DeWalt’s manuals say not to use blades smaller than recommended, and Festool’s thin 1.8mm blades are matched to the riving wedge on specific Festool saws. Only use a smaller blade if your saw’s manual allows it.
Key rule: only use a blade diameter your saw’s manual allows. If the guard does not work properly, do not use the blade, and never fit a smaller blade to a table saw or mitre saw.
Related guides: Circular Saw Blade Sizes | Bore Sizes Guide | Saw Blade Compatibility Guide
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How we compile this guide
We cross-reference compatibility details against manufacturer specifications where available, official tool manuals, and the physical standards that govern fitment (bore sizes, arbor diameters, voltage platforms, connector types). We prioritise primary sources over retailer listings, flag anything we can’t confirm, and re-verify the data on a regular cycle. Where we give a buying recommendation, we tell you the reasoning — not just the link. More on our method →
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