Changeover Time Calculator
How much capacity changeovers consume, what that costs, and how much a changeover reduction — SMED — gives back in production time and smaller economic batches.
Every changeover is time the line makes nothing.
How the changeover time calculator works
Every changeover is time the line makes nothing. Changeovers per week times minutes each is the capacity lost; at the line's rate and margin that is a cost, and it is often the largest avoidable loss on the floor.
SMED — reducing changeover by moving steps off the stopped machine — typically halves it. The prize is not only the time: shorter changeovers make smaller batches economic, which cuts inventory as well.
Formula: lost hours = changeovers × minutes / 60; capacity share = lost / available
Worked examples
| Inputs | Capacity lost to changeovers | Note |
|---|---|---|
| 18 changeovers at 45 minutes | 12.05% | 12% of capacity |
| After SMED | 5.36% | a third of the loss |
| A busy line | 26.79% | over a quarter lost |
FAQFrequently asked questions
What is SMED?
Single-minute exchange of die — Shigeo Shingo's method for cutting changeovers to under ten minutes by doing as much as possible while the machine is still running.
How much can changeover be reduced?
Halving it is routine on the first pass; 75% reductions are common. The first step, separating internal from external work, usually gets a third for nothing.
Why do shorter changeovers reduce inventory?
Because the economic batch size falls with the setup cost. Cheaper changeovers mean smaller batches, less stock and faster response.
What does a changeover really cost?
The lost output times its margin, plus scrap during ramp-up and the labour doing it. The lost-contribution figure here is the one that gets a project funded.
Should I reduce changeovers or make them faster?
Faster. Fewer changeovers means bigger batches and more inventory, which is the problem SMED exists to avoid.
Where these figures come from
- Nakajima (1988) — Introduction to TPM — the origin of Overall Equipment Effectiveness and its six big losses
- Safe Work Australia — the national work health and safety body
Last checked: September 2026. Definitions follow standard operations-management practice; where plants commonly differ, the page says so.