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Six Big Losses OEE Worksheet

The six big losses are the standard way to explain where OEE goes: two availability losses, two performance losses and two quality losses. This worksheet records each one in minutes per line and shift, calculates OEE for every row and shows what share of planned time each loss takes.

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Line or machine	Shift	Planned production time (min)	Equipment failure (min)	Setup and adjustment (min)	Idling and minor stops (min)	Reduced speed (min)	Process defects (min)	Startup rejects (min)	Total loss (min)	OEE
									145	67.8%
									160	64.4%
									131	70.9%
									148	67.1%
									134	70.2%

Total planned minutes

2,250

Total lost minutes

718

OEE across all rows

68.1%

Equipment failure share of planned time

4.1%

Setup and adjustment share

Idling and minor stops share

8.5%

Reduced speed share

Process defects share

2.7%

Startup rejects share

1.6%

Convert quality losses to minutes by multiplying the number of defective units by the ideal cycle time in minutes. Time-based and speed losses are already minutes. Edit the example rows, add your own lines, then export to Excel for a Pareto chart.

Map your downtime codes to the six losses

Optional: send us your reason code list and we can suggest a mapping to the six big losses you can reuse in any ERP or MES.

Optional. The tool and every export work without this. No spam.

How to use the worksheet

Add one row per line and shift for the period you are studying. Enter planned production time, which is the shift minus planned breaks and planned maintenance. Then enter the minutes lost to each of the six categories. Stops and changeovers are measured directly. Slow running is the gap between the ideal cycle time and the actual one multiplied by units. Defects and startup rejects are units times ideal cycle time. The worksheet totals each row, computes OEE and summarizes each loss as a percent of all planned time. Export to Excel to rank the losses in a Pareto chart.

The six big losses explained

The framework comes from total productive maintenance. Equipment failure and setup and adjustment reduce availability. Idling and minor stops and reduced speed reduce performance. Process defects and startup rejects reduce quality. Because every loss is in minutes, they add up neatly to the difference between planned time and fully productive time, so OEE is one minus the total loss over planned time. That view is easier to act on than three percentages because you can see which category is biggest and which line it comes from.

Availability: equipment failure, setup and adjustment.
Performance: idling and minor stops, reduced speed.
Quality: process defects, startup rejects.

Reading the example

The sample rows show a typical pattern: setup and minor stops are bigger than breakdowns, which surprises people who expect maintenance to dominate. Speed loss is often large because it is rarely measured. When you replace the sample with your own data, rank the six summary lines. The biggest line is where to send the first improvement team. Then look at the rows to find if the loss is spread across all lines or concentrated on one machine or shift, which changes the solution from standard work to a specific repair.

Common mistakes

The usual problem is mixing planned and unplanned time. Breaks, planned maintenance and no-demand periods belong outside planned production time. Another is counting minor stops under a minimum length as speed loss in one plant and as stops in another, so write a rule, for example stops under five minutes are minor. Finally, do not double count: a unit scrapped at startup belongs in one category only. If your ERP or MES records reason codes, map each code to one of the six losses once and reuse the map.

Frequently Asked Questions

What are the six big losses?

Equipment failure, setup and adjustment, idling and minor stops, reduced speed, process defects and startup rejects. They come from total productive maintenance and cover every way OEE can fall below 100 percent.

How do I convert defects to minutes?

Multiply the number of scrapped or reworked units by the ideal cycle time per unit in minutes. That gives the production time spent on parts that did not count as good, so it can be added to the time based losses.

Why does the worksheet use planned production time?

OEE measures how well you ran when you planned to run. Planned breaks and scheduled maintenance are excluded so they do not count as losses. Use TEEP if you want to include unscheduled time as well.

Can I use it for a whole plant?

Yes, add a row for each line and shift. The summary lines then show plant level shares. Look at the rows too, because a plant average can hide one machine with a severe breakdown problem.

If you want these losses pulled automatically from downtime reason codes and confirmations in your ERP or MES, Netray can build a read-only dashboard on your own data. The worksheet works without it.

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