Tool Life Calculator
Taylor equation in plain numbers: minutes of cut from surface speed and your tool's n and C — plan tool changes before the edge dies.
Calculator
About this calculator
This tool life calculator applies the Taylor equation VTⁿ = C — still the fastest way to rank cutting speeds against tool change cost. Pair it with the machining time calculator (minutes per part) and the tapping calculator for the full job plan.
Calculation Results
81 min
Tool life · at 100 SFM · doubling speed cuts this to 5.1 min
Formula: T = (C/V)^(1/n)
(300/100)^(1/0.25) = 3⁴ = 81 min of in-cut time to flank wear criterion.
How to use this result
Convert to parts per edge: 81 minutes of cut ÷ your in-cut time per part. Schedule the change at 80% of life — the cost curve of running an edge to death mid-part is brutal compared to an early swap. The 100→200 SFM column shows the speed dilemma: 16× the metal removal rate but 16× faster wear; the optimum depends on what costs more, machine time or tool money.
Continue Your Calculation
Minutes per part times parts per edge — the time math continues here.
Tool life chart (minutes, C = 300)
T = (300/V)^(1/n). Speed sensitivity is the whole story — read across a row to see what one material class buys you.
| Speed V | n = 0.2 (HSS-ish) | n = 0.25 | n = 0.33 (carbide-ish) | n = 0.5 (ceramic-ish) |
|---|---|---|---|---|
| 80 SFM | 741.6 | 197.8 | 54.9 | 14.1 |
| 100 SFM | 243.0 | 81.0 | 27.9 | 9.0 |
| 150 SFM | 32.0 | 16.0 | 8.2 | 4.0 |
| 200 SFM | 7.6 | 5.1 | 3.4 | 2.3 |
| 400 SFM | 0.2 | 0.3 | 0.4 | 0.6 |
Taylor tool life formula
Original form: V × Tⁿ = C — cutting speed times life-to-the-n is constant for one tool-workpiece pair at a defined wear criterion.
Solved for life: T = (C/V)^(1/n). Example: V 100, n 0.25, C 300 → (3)⁴ = 81 min.
Speed doubling: life multiplies by (1/2)^(1/n) — at n 0.25 that is 1/16; at n 0.5, 1/4. High-n tools buy speed; low-n tools buy nothing at speed.
Measuring your own n and C: run the tool at two speeds, log minutes to your wear criterion at each, then n = log(T₁/T₂) / log(V₂/V₁) and C = V₁ × T₁ⁿ. Two honest points from your own material beat catalog numbers for a similar alloy.
Speed from cutter size: speeds and feeds calculator. Minutes per part: machining time calculator.
Typical Taylor exponent ranges by tool class
| Tool class | Typical n | Life lost per +50% speed |
|---|---|---|
| HSS | 0.1–0.2 | ~70–87% (brutal) |
| Carbide (coated) | 0.2–0.4 | ~50–75% |
| Ceramic / CBN | 0.5+ | ~40–45% (tolerant) |
These are class-level ranges for orientation only — the n that matters is measured on your tool, your coating, and your workpiece batch. Tool-maker catalogs and apps publish pair-specific values; use this table only when that data is out of reach.
Frequently Asked Questions
How do you calculate tool life?
Taylor: T = (C/V)^(1/n). Example: V 100 SFM, n 0.25, C 300 → (3)⁴ = 81 minutes of in-cut time.
Where do the Taylor exponent n and constant C come from?
From cutting tests for the specific tool-coating-workpiece pair — tool-maker handbooks/apps, or your own logs. Ranges: HSS 0.1–0.2, carbide 0.2–0.4, ceramic 0.5+. C is the speed giving 1 minute of life. Never reuse a pair's n and C for different material.
The Taylor equation is over a century old — is it still useful?
Yes, with eyes open. Modern models add feed and depth, but Taylor captures the dominant variable — speed — with two numbers you can log yourself. Use it for ranking speeds and planning changes, not absolute wear prediction.
What happens to tool life if I double cutting speed?
Life × (1/2)^(1/n): at n 0.25 that's 1/16 (−94%); at n 0.5, 1/4. High-n tools tolerate speed; low-n tools (HSS) don't — see the exponent table above.
Does feed rate affect tool life?
Yes, but far less than speed. Extended Taylor forms add feed as a much weaker term. Rough guide: speed sets life, feed trims it, depth barely touches it except at very heavy engagement.
What counts as the end of tool life?
The standard criterion is flank wear 0.3 mm average / 0.6 mm max — measured, not guessed. Shop proxies: finish degrading, burrs growing, squeal, power draw rising. Match your change criterion to the data behind your n and C.
How do I measure n and C from my own parts?
Two speeds, two logged lives, solve: n = log(T₁/T₂) / log(V₂/V₁), then C = V₁ × T₁ⁿ. Your own material beats a catalog number for a similar alloy.
How does tool life feed into cutting time planning?
Parts per edge = life ÷ in-cut minutes per part. Schedule changes at ~80% of life. Combine with the machining time calculator — a broken tool mid-part costs more than any early change.
Review & sources
Reviewed: CalcPanel Machining Team
Updated: 2026-11-10