The cost of food waste is everything you bought or made and did not sell, measured in money. To work it out, log every loss for four weeks, add up what those losses cost, and divide by the units you did sell in the same period. That figure, per unit, belongs in your loaded cost alongside ingredients, packaging, your time and energy. Leave it out and your products look more profitable than they are.
The four kinds of waste
Not all waste is the same, and it is not all measured in the same place:
- Trim waste. Peel, seeds, stems, bones. This belongs in each ingredient's yield percentage, not in your waste log. If it is already there, do not count it again.
- Production waste. The loaf that came out flat, the burnt tray, the jar that dropped, the batch that did not set.
- Spoilage. Ingredients that went off before you used them: herbs that wilted, cream that turned, nuts that went rancid.
- Unsold product. What you made and did not sell in time: loaves left at the end of the market, boxes nobody ordered, stock returned by a café.
The last three are the ones you log. Unsold product is often the biggest and the least recorded, because it gets eaten at home, given away or sold cheap without anyone writing it down.
How to keep a waste log
A notebook stuck to the fridge or a note on your phone. Every time something is lost, one line:
| Date | What | Quantity | Reason | Cost |
|---|---|---|---|---|
| 7 Oct | Country loaf | 2 | Unsold | $4.80 |
| 8 Oct | Pumpkin seeds | 1 bag | Rancid | $4.20 |
| 9 Oct | Seeded loaf | 1 | Burnt | $2.40 |
Rules that make it useful:
- Write it down at the time. Nobody remembers at the end of the week.
- The cost is what it cost you, not what you would charge. A loaf you sell for $7.00 that costs $2.40 to make is a $2.40 loss.
- The reason matters. "Unsold", "went off" and "burnt" have different fixes.
- Four full weeks. One week can include a holiday or a rainy market that skews it.
To value each line you need to know what each product costs. If you have a standard recipe card with costs on it, the number comes straight off the card.
How to turn waste into a cost
At the end of the four weeks:
waste cost per unit sold = total waste cost ÷ units sold
Add that to your cost per unit. For a percentage to track month to month, use:
waste as a share of making cost = waste cost per unit ÷ making cost per unit × 100
Why divide by units sold and not units made? Because only sold units bring in money. Each one has to pay for itself and for its share of the ones that were lost.
Worked example: a sourdough micro-bakery
You bake sourdough three days a week, 20 loaves each time: 60 a week, 240 over four weeks. Each loaf costs you $2.40 to make (flour, salt, seeds, paper bag and oven energy) and sells for $7.00.
What your log showed after four weeks:
| Kind of waste | Working | Cost |
|---|---|---|
| Unsold | 18 loaves × $2.40 | $43.20 |
| Production | 6 loaves flat or burnt × $2.40 | $14.40 |
| Spoilage | Seeds that went rancid, a bag of rye with weevils | $7.20 |
| Total | $64.80 |
What you sold: 240 − 18 − 6 = 216 loaves.
Waste cost per loaf sold: 64.80 ÷ 216 = $0.30.
What it means:
- Your cost per loaf sold goes from $2.40 to 2.40 + 0.30 = $2.70.
- Waste adds 0.30 ÷ 2.40 = 12.5% to your making cost.
- On a $7.00 loaf, 0.30 ÷ 7.00 = 4.3 points of margin go to waste.
- By count, 24 of 240 loaves never earned anything: 10% of production.
Getting some back. Say you start selling unsold loaves as day-old at $3.50 and 12 of the 18 go that way. You recover 12 × 3.50 = $42.00. Net waste cost: 64.80 − 42.00 = $22.80, or 22.80 ÷ 216 = $0.11 per full-price loaf. Only count recovery you actually collect, not what you plan to.
Where to look next: unsold loaves are two thirds of the cost ($43.20 of $64.80). Look at the log by bake day. If one day always leaves loaves over, bake fewer that day or take preorders for it.
How to reduce waste
- Make what you sell, not what you hope to sell. Use your sales by day to set quantities. Making smaller batches on quiet days is easier if you know how to scale a recipe down cleanly; see how to scale a recipe without breaking the cost.
- First in, first out. Put older stock at the front and use it first.
- Buy perishables more often and in smaller amounts, even if the price per kilo is a little higher. Compare what you save on price with what you lose to spoilage.
- Take preorders. Orders by a set time tell you how much to make.
- Standardise the recipe. A lot of production waste comes from improvising: quantities by eye, different timings. A recipe card cuts it down.
- Have a plan for leftovers, where it is safe: a day-old price, another product such as croutons. Recovery reduces your waste cost only when it turns into money.
Packaged products also carry the problem of a use-by or best-before date. For that, see the guide on shelf life and the cost of unsold stock. And for how waste fits with yield and portions, the overview on recipe costing puts it all together.
Do it with the calculator
In the food cost calculator multiply the waste cost per unit sold from your log by the units in a batch and add it to "Gas, power and other per batch"; you will see the loaded cost and the price you need with waste included.
Frequently asked questions
How do I calculate food waste percentage?
Divide what you lost by what you produced, times 100. If you bake 240 loaves in a month and 24 are never sold, your finished-product waste is 24 ÷ 240 = 10%. For costing, turn it into money as well.
What value do I put on an unsold product?
What it cost you to make: ingredients, packaging and whatever else you spent on it. Do not use the selling price; what you lost is the cost, not a sale that never happened.
Does food I eat or give away count as waste?
Yes. If it was not sold, it is waste for the business, even if it was not thrown away. Log it anyway; what you do with it is a separate matter.
How often should I measure waste?
Do one full four-week log. After that, checking one week every so often is enough, or whenever you change product, supplier or the way you sell.