Changeover Reduction (SMED) Savings Calculator
SMED, single minute exchange of die, is the method of shortening setups by converting internal work (machine stopped) into external work (machine running). This calculator shows what a given percentage reduction is worth in hours, capacity and money, so you can decide where to invest first.
Your numbers
From last piece of the old product to first good piece of the new one.
Typical first SMED projects remove a large share by moving internal work outside the stop.
Contribution margin per hour of running time, or the cost of an hour of idle labor and machine.
Total scheduled machine hours per week, for example 120 for 3 shifts on 5 days.
Your results
Machine value and labor cost overlap if the crew would otherwise be idle. Count only the benefit you will actually capture, for example more sellable output or avoided overtime.
Annual value of released machine time vs reduction
Sweeps Targeted reduction from 0 to 80, holding your other inputs fixed.
Compare planned and actual setup times
Optional: we can sketch how to pull actual setup durations from your ERP or MES for review.
Optional. The tool and every export work without this. No spam.
How to use it
Time several recent changeovers from the last good part of one product to the first good part of the next, and enter the average. Add how many changeovers you run per week, the production weeks per year and the margin per running hour. Set a targeted reduction, then read the hours released and their value. The chart shows the value across reductions from zero to 80 percent, which helps you decide whether an expensive quick-change fixture is justified compared with simple standard work and kitting.
- Measure to first good part, not first part
- Use an average of at least five recent changeovers
- Enter the crew size honestly, support staff included
The method and formulas
Shigeo Shingo's SMED separates setup into internal elements (done with the machine stopped), external elements (done while it runs) and waste such as searching for tools. New time is current time times one minus the reduction. Hours released equal changeovers per week times weeks times minutes saved, divided by 60. Capacity gained is those hours as a share of scheduled hours. Value is hours times margin per running hour. The labor line is a separate view and should not be added to machine value when the crew is simply redeployed.
Worked example and reading the output
Twelve changeovers a week at 90 minutes, cut by 40 percent, save 36 minutes each. Over 50 weeks that is 360 hours, about 6 percent of 6,000 scheduled hours. At 180 dollars margin per hour the machine time is worth 64,800 dollars a year. If changeovers are the reason you run large batches, the real prize is smaller lots and less inventory, which this model does not price. Pair it with the changeover element worksheet to find which elements to move outside first.
Common mistakes
Counting released hours as value when the machine would still be idle for lack of orders is the most common error. Another is not fixing the new method: without standard work and audits, gains erode within months. Teams also forget changeover includes first-article approval and adjustments, which are often the largest part of the time and are not removed by quick-release clamps alone.
- Value only hours you can sell or avoid paying for
- Lock gains in with a standard changeover sheet
- Include first-article and adjustment time in the baseline
Frequently Asked Questions
What is a realistic SMED reduction?
First projects frequently remove 30 to 50 percent of changeover time by separating internal and external work and standardizing. Deeper cuts need design changes such as quick-clamp fixtures and pre-staged tooling.
Should I use the setup time in the ERP routing?
Only if it is accurate. Routing setup times are often outdated estimates. Time real changeovers with a stopwatch or machine data, then correct the routing so planning and costing use true values.
Does shorter changeover mean smaller batches?
It can. When setup is cheap, economic batch sizes fall, which reduces work in process and lead time. The calculator does not price that benefit, so the real return is often higher than shown.
Is labor value additive to machine value?
Not usually. Both measure the same stopped time. Use machine value when the machine is the constraint, and labor value when it is not. Adding both double counts.
If changeover times are recorded in your ERP routings or MES, we can help compare planned versus actual setup times automatically.
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