Arbor Size
Affiliate link — we may earn a commissionThe arbor is the shaft that the blade mounts onto. Arbor size is the diameter of the hole in the center of the blade. Most 7-1/4-inch circular saw blades use a 5/8-inch arbor. Miter saw blades (10 or 12 inch) typically use a 5/8-inch arbor too. Table saw blades also standardize on 5/8-inch. Smaller 4-1/2-inch blades for compact saws might use a 3/8-inch or 7/8-inch arbor. If the blade arbor doesn't match the saw, the blade won't mount. Reducer bushings exist but add runout and aren't recommended for precision work.
Why It Matters
A blade with the wrong arbor hole doesn't fit, period. Check your saw's arbor size before buying replacement blades. It's printed on the blade guard or in the manual. Using a bushing to adapt sizes adds vibration and reduces cut accuracy.