Chip Load Calculator
Already running a feed rate and RPM? Work backward to find out what chip load per tooth you're actually cutting at, and check it against a sane range.
Starting chip loads by tool diameter
| Tool diameter | HSS, starting IPT | Carbide, starting IPT |
|---|---|---|
| 1/8" | 0.0005–0.001 | 0.001–0.002 |
| 1/4" | 0.001–0.002 | 0.002–0.004 |
| 3/8" | 0.002–0.003 | 0.003–0.006 |
| 1/2" | 0.003–0.004 | 0.004–0.008 |
| 3/4" | 0.004–0.006 | 0.006–0.010 |
| 1" | 0.005–0.007 | 0.008–0.012 |
General starting points for mild steel to aluminum in a rigid setup — softer materials and shorter stickouts can run toward the high end, harder materials and long stickouts toward the low end.
Why check chip load instead of just trusting the feed rate
A feed rate that "sounds reasonable" can hide a chip load that's much too light or much too heavy once the actual RPM and flute count are accounted for — the same 40 IPM is a healthy chip load on a 2-flute tool at 5,000 RPM and a dangerously thin one on a 6-flute tool at the same speed. Chip load per tooth = feed rate ÷ (RPM × flute count) backs the actual per-tooth number out of whatever feed and speed you're already running.
Too light is its own problem, not just too heavy
It's tempting to assume a lighter chip load is always safer, but running well below the recommended range means the tool is rubbing more than cutting — each flute skates across some of the material instead of shearing it cleanly, which generates excess heat, accelerates edge wear, and can actually shorten tool life compared to a properly loaded chip. If your calculated chip load lands well under the table above, that's usually a sign to speed up the feed, not a reason to feel good about being "gentle" on the tool.
This is a range, not a target to hit exactly
Radial engagement, tool stickout, workholding rigidity, and finish requirements all shift where in the range you actually want to sit — a full-slot cut in a rigid vise can run toward the top of the range, while a thin-walled part with a long tool stickout should run well below it. Use the chip load number as a sanity check against the table, then adjust for your specific setup rather than treating either number as an absolute.