Machining Time Calculator
Cutting time for milling and turning passes, broken down so you can see where the minutes actually go — and reversed, so you can ask "what feed do I need to hit this cycle time?" Useful for quoting, for choosing between two strategies, and for sanity-checking a number that looks wrong.
Include lead-in and lead-out.
Rapids, retracts, repositioning.
Working back from a cycle time you have been given, rather than forward from one you have chosen.
Where the minutes actually go in a machining cycle
Cutting time itself is the easy part: time = length ÷ feed rate, multiplied by the number of passes. A 200 mm cut at 800 mm/min takes 15 seconds; six passes takes 90. The reason a real cycle takes far longer than the sum of those numbers is everything around them — rapids and retracts between passes, tool changes, probing, and the setup carried once per batch.
That distinction matters when people try to speed a job up. Doubling the feed rate on a cycle that is 30% cutting and 70% air time and tool changes does not halve anything — it takes about 15% off. The first question on a slow cycle is nearly always what proportion is actually cutting?, and it is very often lower than people assume. This calculator splits it out for exactly that reason.
Setup is the other half of the story, and it is the reason quantity changes price so sharply. A 45-minute setup spread across one part adds 45 minutes to that part. Across fifty parts it adds 54 seconds each. This is the single biggest reason a prototype costs what it does, and why the same part in batch is a different proposition entirely — nothing about the machining changed, only what the setup is divided by.
A note on turning specifically: spindle RPM changes with diameter, so on a facing cut or a large-diameter part the surface speed falls as the tool moves inward unless you use constant surface speed (G96), which holds Vc by ramping RPM up as diameter drops. If you are calculating facing time from a single RPM figure, it will be wrong — the feed in mm/min is not constant across the face.
Use this to compare two strategies honestly — a light, fast, high-rpm pass against a deep, slow one — rather than to price work. Pricing needs machine rate, tooling cost, inspection, risk and the rest, which is why our quotes come from an engineer looking at your actual drawing rather than from a formula.
Machining time — FAQ
How do you calculate machining time?
Cutting time = cut length / feed rate, multiplied by the number of passes. A 200 mm cut at 800 mm/min takes 0.25 minutes (15 seconds) per pass. Real cycle time then adds non-cutting moves, tool changes and setup.
Why is my actual cycle time longer than the calculation?
Because cutting is usually only a fraction of the cycle. Rapids, retracts, tool changes, probing and repositioning often account for more of the clock than the cutting does. If a cycle is 30% cutting, doubling your feed rate only removes about 15% of the total.
How does quantity affect machining cost per part?
Setup is carried once per batch, so it divides down. A 45 minute setup adds 45 minutes to a single part but only 54 seconds each across fifty. This is the main reason unit price falls steeply from prototype to batch.
What is constant surface speed (G96)?
On a lathe, surface speed depends on diameter. G96 holds the cutting speed constant by automatically increasing RPM as the diameter reduces — essential for facing cuts and large-diameter work, where a fixed RPM would mean the surface speed collapses as the tool moves inward.
Can I use this to price a machined part?
No — it calculates cutting time, not cost. Real pricing needs machine rate, tooling, fixturing, inspection, material and risk. Send us a drawing for a same-day quote from an engineer who has actually looked at the part.
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Related: Feeds & speeds · CNC cost driver checker · Material selector · Rapid Prototyping