It is Monday morning at a biscuit factory near Leicester, England. The production meeting lasts ten minutes and is full of numbers: Line 2 ran at 61 per cent OEE, the changeover from a chocolate biscuit to a plain one took 95 minutes instead of 60, dough yield was down a point and give-away on the 200 g packs crept up again. To the finance and sales people in the room it sounds like code. It is not. OEE in food manufacturing, yield and changeover time decide the cost of every pack long before the month-end accounts do.
In short
- OEE (overall equipment effectiveness) = availability × performance × quality. It measures how much of the planned production time becomes good product at ideal speed.
- Small losses multiply: a line with 90 % availability, 90 % performance and 98 % quality has an OEE of about 79 %.
- Yield is saleable output ÷ input. Raw materials are often the largest single cost in a food product, so a one or two point yield loss can outweigh savings elsewhere.
- Changeover and cleaning time is a fixed cost shared across the run, so short runs cost more per unit. Allergen cleans must never be cut to save time.
- Raising OEE frees capacity without new equipment. OEE is best used to track one line over time.
What is OEE in food manufacturing?
OEE, or overall equipment effectiveness, is a single percentage that shows how much of a line’s planned production time produces good product at the line’s ideal speed. It multiplies three factors, each answering one question:
- Availability: of the planned production time, what share did the line actually run?
- Performance: while it ran, how close was it to its ideal speed?
- Quality: of everything made, what share was good first time?
OEE = Availability × Performance × Quality
OEE comes from total productive maintenance (TPM), developed in Japanese manufacturing, which groups losses into “six big losses”:
| Loss | OEE factor | Food line example |
|---|---|---|
| Breakdowns | Availability | Seized conveyor bearing, failed filler valve |
| Set-up and adjustment | Availability | Flavour or pack-size changeover, allergen clean |
| Small stops | Performance | Jammed lids, film breaks, a fallen bottle at the capper |
| Reduced speed | Performance | Running a filler slower to avoid spills |
| Start-up rejects | Quality | Underweight packs while the filler settles after a changeover |
| Production rejects | Quality | Poor seals, misprinted date codes |
How do you calculate OEE? A worked example
You calculate OEE from four numbers in the shift record: planned production time, run time, total units made and good units.
Worked example
A biscuit packing line has an ideal speed of 120 packs per minute and is planned to run for 480 minutes in a shift (breaks excluded).
Availability. The line lost 80 minutes: a 45-minute changeover, a 25-minute breakdown and 10 minutes waiting for quality release. Run time = 480 − 80 = 400 min. Availability = 400 ÷ 480 = 83.3 %.
Performance. In 400 minutes at 120 packs/min the line could have made 48,000 packs. It made 42,000. Performance = 42,000 ÷ 48,000 = 87.5 %.
Quality. Of the 42,000 packs, 1,680 were rejected for poor seals or low weight, leaving 40,320 good packs. Quality = 40,320 ÷ 42,000 = 96.0 %.
OEE = 0.833 × 0.875 × 0.960 = 0.70, or 70 %.
Check: good packs ÷ (ideal rate × planned time) = 40,320 ÷ (120 × 480) = 40,320 ÷ 57,600 = 70 %.
Turning the losses back into minutes shows where the other 30 per cent went:
| Where the time went | Minutes | Share of planned time |
|---|---|---|
| Stops (availability loss) | 80 | 16.7 % |
| Slow running and minor stops: 400 − (42,000 ÷ 120) | 50 | 10.4 % |
| Rejects: 1,680 ÷ 120 | 14 | 2.9 % |
| Fully productive time: 40,320 ÷ 120 | 336 | 70.0 % |
| Total | 480 | 100 % |
Here stops cost the most time (80 minutes, more than half of it the 45-minute changeover), followed by slow running and minor stops (50 minutes). That tells the team where to look first.
What is a good OEE score for a food line?
There is no single correct target. The most useful comparison is a line against its own history, measured the same way each time.
A figure of 85 per cent is commonly cited as a “world-class” benchmark, usually broken down as about 90 per cent availability, 95 per cent performance and 99 per cent quality (0.90 × 0.95 × 0.99 = 0.846). It comes from the TPM tradition, not from food-industry data, so treat it as a reference point rather than a standard. Food lines carry losses many other industries do not: wet cleaning, allergen changeovers, short seasonal runs and variable raw materials.
Definitions matter more than targets. Some sites exclude planned cleaning from planned production time; others count it as downtime. In the example above, adding a 60-minute planned clean to the planned time would cut OEE from 70 % to 40,320 ÷ (120 × 540) = 62.2 %, with nothing changed on the floor. Agree the definition, write it down and keep it fixed.
What is yield, and why does a small loss cost so much?
Yield is the share of what goes in that comes out as saleable product. Because raw materials are often the largest single cost in a food product, small changes in yield move cost more than most other factory numbers.
Yield (%) = saleable output ÷ input × 100
Yields multiply across stages: a cake that loses 12 % of its batter weight in baking and 5 % of the baked weight in trimming has an overall yield of 0.88 × 0.95 = 0.836, or 83.6 %. The real ingredient cost per kilogram of saleable product is the recipe cost divided by the yield.
Worked example
A cooked chicken line buys raw breast at 5.00 currency units per kg. At a 78 % cooking yield, each kilogram of cooked product carries 5.00 ÷ 0.78 = 6.41 units of raw material.
If yield slips to 76 %, that becomes 5.00 ÷ 0.76 = 6.58 units, about 0.17 more per kg (2.6 %).
On 400 tonnes of cooked product a year, the line now needs 400 ÷ 0.76 = 526.3 t of raw chicken instead of 400 ÷ 0.78 = 512.8 t: 13.5 t more, worth about 67,500 currency units.
Give-away is product handed over free because packs are filled above their declared weight. Weights and measures rules in many countries, often based on the OIML recommendation on prepackages, require the average to reach the declared quantity and limit how many packs may fall short, so lines aim slightly high. Frozen peas packed at an average of 508 g in 500 g bags give away 8 g each: across 2 million packs a year, 8 g × 2,000,000 = 16,000 kg.
Why do changeovers make short runs expensive?
A changeover is the switch from one product, recipe or pack format to another, and its cost is fixed: the same 90 minutes is lost whether 5,000 or 500,000 units follow. It covers emptying, cleaning, swapping parts and settings, and running until the product is back in specification. Allergen changeovers need a validated clean, verified before restart. In dairies, breweries and drinks plants much cleaning is clean-in-place (CIP): rinses, hot detergent and sanitiser are circulated through pipes, tanks and fillers at controlled time, temperature, concentration and flow, without taking the equipment apart.
Take a sauce line that costs 1,200 currency units an hour while occupied, makes 6,000 good jars an hour and needs 1.5 hours per changeover. Each changeover costs 1.5 × 1,200 = 1,800 units, and running time costs 1,200 ÷ 6,000 = 0.20 units per jar.
| Run length | Run time | Changeover cost per jar | Running cost per jar | Line cost per jar |
|---|---|---|---|---|
| 6,000 jars | 1 h | 1,800 ÷ 6,000 = 0.30 | 0.20 | 0.50 |
| 30,000 jars | 5 h | 1,800 ÷ 30,000 = 0.06 | 0.20 | 0.26 |
| 120,000 jars | 20 h | 1,800 ÷ 120,000 = 0.015 | 0.20 | 0.215 |
The short run costs more than twice as much per jar in line time as the long one, which is why minimum order quantities exist. Two tools help. SMED (single-minute exchange of die), developed by Shigeo Shingo, moves preparation outside the stoppage, so labels, film and change parts are ready before the line stops. Good scheduling runs from allergen-free to allergen-containing, light to dark and mild to strong, so many changeovers need only a routine clean. Never shorten an allergen clean or skip its verification to protect OEE; undeclared allergens are a common cause of food recalls.
How do OEE, yield and changeovers show up in product cost?
They set two of the biggest lines in a product’s cost of goods: raw material cost per unit, through yield and give-away, and conversion cost per unit, through OEE and changeovers. Conversion cost is the cost of turning ingredients into product: labour, energy, cleaning, maintenance and line overheads.
Good units per planned hour = ideal rate per hour × OEE
Conversion cost per good unit = line cost per hour ÷ good units per planned hour
Back to the biscuit line: its ideal rate is 120 packs per minute, or 7,200 per hour. At 70 % OEE it delivers 7,200 × 0.70 = 5,040 good packs per planned hour. If the line costs 1,260 currency units an hour, conversion cost is 1,260 ÷ 5,040 = 0.25 per pack. At 60 % OEE, output falls to 4,320 packs an hour and cost rises to 1,260 ÷ 4,320 = 0.29 per pack. Going from 60 to 70 % OEE gives about 17 % more good packs from the same line and crew (70 ÷ 60 = 1.17).
What can commercial and finance teams do to improve these numbers?
Commercial and finance decisions shape these numbers as much as engineering does:
- Ask for the definition before the number: what counts as planned production time, and is cleaning included?
- Price small runs honestly, with changeover and cleaning time in the quote.
- Forecast accurately and early, so planners can build longer runs and sensible sequences.
- Question range complexity: every extra flavour or pack size adds changeovers.
- Before approving a new line for capacity, ask what OEE the existing lines achieve and what is holding it back.
- Treat cleaning and allergen controls as safety activities. Savings come from faster, better-planned changeovers, never from skipping them.
These are the questions Food Technology for Non-Technical Professionals trains you to ask. For the science your technical colleagues work with, from specification sheets to HACCP, Food Science for Non-Scientists explains it in plain language.
Frequently asked questions
What does OEE stand for?
OEE stands for overall equipment effectiveness. It is a single percentage that compares the good output a line actually made with what it could have made at its ideal speed for the whole planned production time. Because it is calculated as availability × performance × quality, it also shows which kind of loss is holding the line back.
Is 85 per cent OEE world class?
A figure of 85 per cent is a commonly cited benchmark from the total productive maintenance (TPM) tradition, not a standard or a measured food-industry figure. Food lines carry losses that many other industries do not, such as wet cleaning, clean-in-place cycles, allergen changeovers and short seasonal runs. Use it as a reference point at most, and judge each line by its own trend.
Should cleaning time count against OEE?
Either convention can work if it is written down and applied consistently. Some sites count planned cleaning as downtime so that its cost stays visible; others exclude it from planned production time and report it separately. The choice can move the headline figure by several points, so never compare OEE between sites without checking the definition. What matters is that cleaning time is measured and improved, never cut short.
What is the difference between yield and OEE?
Yield measures materials: the share of what goes in that comes out as saleable product. OEE measures time and equipment: the share of planned time that produces good product at ideal speed. A line can score well on one and badly on the other, for example running fast while overfilling packs. Yield drives raw material cost per unit; OEE drives conversion cost per unit, so both belong in any product costing.
What is give-away in food packing?
Give-away is product handed to customers free because packs are filled above their declared quantity. Fillers vary, so lines aim slightly high to stay within weights and measures rules. A few grams per pack becomes tonnes across a year. It is reduced by measuring fill weights accurately, feeding checkweigher data back to the filler and using more consistent filling equipment, never by deliberately underfilling.
Next step. Food Technology for Non-Technical Professionals explains in plain language how a food factory turns raw materials into finished packs, and how yield, throughput, OEE, downtime and changeovers drive cost, with case studies and a yield-adjusted costing exercise for a new product. It ends with a proctored final assessment and an ASC certificate. You can also see all eleven food science and technology courses.
Sources. Seiichi Nakajima, Introduction to TPM: Total Productive Maintenance (Productivity Press, 1988); Shigeo Shingo, A Revolution in Manufacturing: The SMED System (Productivity Press, 1985); ISO 22400-2:2014, Key performance indicators for manufacturing operations management, Part 2: Definitions and descriptions; International Organization of Legal Metrology (OIML), Recommendation on the quantity of product in prepackages; Codex Alimentarius Commission, General Principles of Food Hygiene, CXC 1-1969 (revised 2020).
This article is general guidance on manufacturing performance measures and is not a substitute for the applicable standard, your national legislation or the advice of a qualified professional.