OEE calculator

What it works out

The oee calculator turns records from the business into a figure for this decision: the full three-part measure, showing which part is losing the most. Use it when the responsible production supervisor needs a consistent answer for this specific task. The answer uses only the values entered. Record the measurement period beside it.

What you need

Use the same item, period and measurement unit for related inputs. If a figure comes from an estimate rather than an actual record, mark it as estimated. Keep your original figures beside the result.

The formula

In plain words, calculate OEE percent using the measured inputs below. The expressions are shown without hidden rounding so they can be checked by hand.

• availability percent: availability_percent = run_time_minutes/planned_time_minutes*100.
• performance percent: performance_percent = ideal_cycle_seconds*total_count/(run_time_minutes*60)*100.
• quality percent: quality_percent = good_count/total_count*100.
• OEE percent: oee_percent = (availability_percent/100)*(performance_percent/100)*(quality_percent/100)*100.

Formula basis from the supplied taxonomy: OEE = availability x performance x quality; availability = run time ÷ planned time; performance = (ideal cycle time x total count) ÷ run time; quality = good count ÷ total count. Availability = run time / planned time. Performance = ideal time for all units / run time. Quality = first-pass good units / total units.

A worked example

Illustrative example: a distribution business uses the figures in the table above. These are example inputs, not industry averages. For this example, the main figures are run time minutes: 410 minutes, planned time minutes: 480 minutes, ideal cycle seconds: 24 seconds, total count: 890 pieces.

1. Availability percent: run_time_minutes/planned_time_minutes*100. With the example figures, 410.0 / 480.0 * 100 gives 85.42 %.
2. Performance percent: ideal_cycle_seconds*total_count/(run_time_minutes*60)*100. With the example figures, 24.0 * 890.0 / (410.0 * 60) * 100 gives 86.83 %.
3. Quality percent: good_count/total_count*100. With the example figures, 850.0 / 890.0 * 100 gives 95.51 %.
4. Oee percent: (availability_percent/100)*(performance_percent/100)*(quality_percent/100)*100. With the example figures, 85.41667 / 100 * (86.82927 / 100) * (95.50562 / 100) * 100 gives 70.83 %.

How to act: Use the result to check it against committed machine time. Write down the input date and the assumption that could move most.

How to read the result

Example bands, change them for your business:

• Comfortable: Your result meets the target for this item or reporting period. Keep the calculation with its source records and check it against committed machine time.
• Watch: The result is close to your action limit, or it changed since the previous calculation. Recheck run time minutes and planned time minutes using the original records.
• Act: The result breaks a limit already agreed by the manager or owner. Record the difference, name a responsible person, and agree a correction date. For an operational starting point, read [Production delays](/problems/production-delays) and [Production plan to output](/processes/production-plan-to-output). Do not use these example bands as published industry benchmarks.

Copy it into a spreadsheet

Create a sheet with column A for the label and column B for the number or formula. The expressions work in Excel or Google Sheets. Keep input cells editable and result cells protected from typing.

For any formula containing a divisor, enter a value above zero. For any monetary output, format the cell in Indian rupees. Do not replace the cells with rounded figures until the final display.

What this calculator leaves out

• A machine may be free in the plan while the operator, tool or drawing is unavailable.
• OEE uses three ratios. Cycle time must refer to the same unit and machine as run time and the total count.
• The formula does not check whether the records are complete. Take cycle times from recent job cards, not machine brochures. Count setup, changeovers, breakdowns and operator breaks separately.

Common mistakes

1. Mixing periods. Using run time minutes from one month with planned time minutes from another produces a number that looks precise but is hard to act on.
2. Trusting old figures. Recheck the relevant source record before reusing last month's saved inputs. Compare the result with the actual shift report for at least several runs before setting a promise date.
3. Treating an estimate as approval. Record which assumptions were entered by hand. Get the relevant owner, accountant or technician to check unusual values.

A number like this helps only if someone works it out again when things change.

Questions people ask

Where do I find the numbers for oee calculator?

Read run time minutes from the job card, shift report, machine log or maintenance register. Read planned time minutes from the job card, shift report, machine log or maintenance register. Keep all inputs from the same period.

Can I use this number to approve a purchase or payment?

Use it as a first check. Use the result to check it against committed machine time. Write down the input date and the assumption that could move most. If the result affects tax, legal duties, workplace safety or a major investment, obtain the appropriate review.

When should I calculate it again?

Recalculate when a meaningful input changes, and at the next regular review of the relevant register. Save the date and the input values so changes can be explained.