Router bit speed calculator
Enter the bit diameter and your router's RPM setting — get the recommended speed window, the rim speed at your setting, and a warning when you are over the chart maximum. The full router bit speed chart is below the tool, printable for the shop wall. More shop math lives on the woodworking hub.
18,000 – 24,000 RPM
recommended window for this bit
| Chart maximum for this bit | 24,000 RPM |
| Rim speed at your setting | – |
Within the recommended window
Generic maximums for carbide bits in wood — INCRA/JessEm lift-manual chart (carbide bits in wood); never exceed the bit manufacturer’s rating. Bits over 3-1/2 in clamp to the last chart row; many panel raisers carry a lower rating and are table-mount only.
Router bit speed chart
Maximum RPM per bit-diameter bracket, carbide bits in wood. Print it and hang it next to the router table.
| Bit diameter | Max RPM |
|---|---|
| Up to 1 (≤ 25 mm) | 24,000 RPM |
| Over 1 to 2 (25–51 mm) | 18,000 RPM |
| Over 2 to 2-1/2 (51–64 mm) | 16,000 RPM |
| Over 2-1/2 to 3-1/2 (64–89 mm) | 12,000 RPM |
Why rim speed sets the limit
Router RPM limits exist because of rim speed, not motor power. The carbide tips on a bit travel at π × diameter × RPM feet per minute, so tip speed scales linearly with diameter. A 1 in straight bit at 24,000 RPM moves its edges at about 6,283 fpm, roughly 71 mph. Put a 3 in raised-panel bit on the same 24,000 RPM setting and the tips are doing 18,850 fpm — about 214 mph. Drop that bit to the chart maximum of 12,000 RPM and rim speed halves to 9,425 fpm, back inside what brazed carbide joints are rated to survive. That is why the chart steps down as diameter climbs: each bracket holds rim speed in a survivable band rather than picking an arbitrary number.
Running slower than the floor of the range is not free either. Too few RPM at a fixed feed makes each cutting edge take a heavier chip, which tears grain and vibrates the router; too slow a feed at the right RPM rubs instead of cuts and burns the wood. Aim for the middle of the bracket, keep the feed steady, and make deep profiles in several passes. If the bit maker prints a lower maximum on the shank or box, that number wins over any chart.
While you are setting up: the board foot calculator prices the stock, the cut list optimizer lays out your sheet goods, and the shelf sag calculator checks whether the panel you are routing will hold its load.
Frequently asked questions
What RPM should I use for a 1/2 in router bit?
Up to 24,000 RPM. A 1/2 in bit sits in the smallest chart bracket (bits up to 1 in), where the recommended maximum is 24,000 RPM and the sensible working window is roughly 18,000–24,000 RPM — a mid-range dial setting on a variable-speed router.
Why do large router bits have to spin slower?
Rim speed. Tip speed equals pi times diameter times RPM, so it grows in direct proportion to bit diameter. A 3-1/2 in bit at 24,000 RPM would throw its carbide tips at about 22,000 fpm — roughly 250 mph — far beyond what brazed carbide joints are rated for. Halving the RPM halves the rim speed, which is why the chart caps big bits at 12,000 RPM.
What causes router burn marks on wood?
Heat from rubbing instead of cutting. The two usual causes are feeding too slowly — or stopping mid-cut — so the bit polishes the wood, and running more RPM than the bit or the wood can take. Stay under the chart maximum, keep a steady feed, take deep profiles in several passes, and swap in a sharp bit: dull carbide burns at any speed.
Can I use large bits in a hand-held router?
Small and medium bits, yes — hand-held routing suits bits up to about 2 in. Anything larger, especially raised-panel bits in the 3 in class, belongs in a table-mounted router with variable speed: the table carries the weight, a fence controls the cut, and you can actually reach the 12,000 RPM the chart demands.
The chart says one number, my bit says another — which wins?
The bit manufacturer wins, always. The chart is a generic maximum for carbide bits in wood, reprinted from router-lift manuals; a maker may rate a specific bit lower because of its geometry, shank size or brazing. The rating on the shank, box or product page is the ceiling — treat this chart as the fallback when no rating is given.