Free tool
SMED changeover calculator
SMED (single-minute exchange of die) shortens changeovers by moving work the crew can do while the machine is still running, external work, out of the stop. The changeover time that remains is the internal work: the steps that can only happen with the machine stopped.
New changeover timeequalsInternal work − Minutes moved to external
Time freed per weekequalsMinutes moved × Changeovers per week
Capacity freedequalsTime freed (seconds) divided by Cycle time (seconds)
Smaller batch sizeequalsBatch size × New changeover time divided by Changeover time today
Done with the machine stopped: today's changeover time
Already done while the machine runs
Fetching tools, preheating, presetting, paperwork
To turn freed time into units
Units made between changeovers
Pre-filled with the worked example. Changeover time runs from the last good part of one product to the first good part of the next.
New changeover time
60 min
Down from 90 min: 30 min (33.3%) saved on every changeover.
Machine time freed
3 h / week
180 min at 6 changeovers a week
Capacity freed
240 units
Per week, if batch sizes stay the same
Or a smaller batch
1,000 units
Up to 9 changeovers a week in today's 540 min
Internal share of the work
82% → 55%
Of 110 min of changeover work
Next step
Want to track this every week?
Bring this result to a 45-minute demo and we will show where it fits in LeanSuite's SMED.
How to calculate it
Split the work, then move it
Film or time one changeover and list every step. Mark each one internal (the machine must be stopped) or external (it could be done while the machine runs). Today's changeover time is the internal total.
Then find the internal steps that could be done before the stop or after the restart: fetching tools and material, preheating, presetting, paperwork. Those are the minutes you can make external. Steps you speed up without moving them, such as quick-release clamps, simply lower the internal time.
Changeovers count against availability in OEE, and shorter ones make smaller batches practical, the basis of just-in-time production. To see what the stop itself costs, use the downtime cost calculator.
Worked example
Illustrative numbers, not a benchmarkA press has 90 minutes of internal changeover work and 20 minutes of external work. The team finds 30 internal minutes it can move to external. It changes over 6 times a week, runs a 45-second cycle and makes batches of 1,500.
Step 1
New changeover time = 90 − 30 = 60 min, 33.3% shorter.Step 2
Time freed = 30 × 6 = 180 min = 3 hours a week.Step 3
Capacity freed = 180 × 60 ÷ 45 = 240 units a week.Step 4
Or smaller batches: 1,500 × 60 ÷ 90 = 1,000 units, with 6 × 90 ÷ 60 = 9 changeovers fitting in today's 540 minutes a week.Step 5
Internal share of the work: 90 of 110 minutes (82%) before, 60 of 110 (55%) after.
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<iframe src="https://www.theleansuite.com/tools/smed-changeover-calculator/embed" title="SMED changeover calculator by LeanSuite" width="100%" height="1310" style="border:0;max-width:1000px" loading="lazy" allow="clipboard-write"></iframe>
<p style="font:13px/1.4 sans-serif"><a href="https://www.theleansuite.com/tools/smed-changeover-calculator">SMED changeover calculator</a> by LeanSuite</p>How LeanSuite helps
LeanSuite watches a video of your changeover, separates internal and external tasks and recommends a leaner sequence.
See SMEDFAQ
SMED changeover calculator: common questions
Internal work can only be done with the machine stopped, such as removing one die and fitting the next. External work can be done while the machine is still running the previous job, such as fetching tools, staging material or preheating the next die. SMED moves as much work as possible from internal to external.
Changeover time runs from the last good part of one product to the first good part of the next, so it includes adjustments and trial runs. Only internal work adds to it; external work done while the machine runs does not.
Every internal minute moved to external comes off the changeover. Multiply the minutes moved by the number of changeovers per week for the machine time freed each week, and divide that by the cycle time for the extra units it could make.
Large batches are often run to spread a long changeover over more units. With a shorter changeover you can change over more often in the same weekly changeover time, so each batch can be smaller: today's batch size times the new changeover time divided by today's changeover time. Smaller batches mean less stock between runs and a faster response to orders.
Not both in full. The freed time can go into making more units at today's batch size, or into more frequent changeovers with smaller batches, or be split between the two. The calculator shows both ends so you can choose.
No. Single-minute exchange of die refers to the goal of a single-digit number of minutes. It is a direction to work toward; any internal minutes removed free up machine time.
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