Quick answer
Food waste percentage = food wasted ÷ total food × 100. Wasting 120 of 1,500 units (kilograms, portions or dollars) is 8%.
Enter the food wasted and the total food. The calculator returns the waste percentage.
Related tools: Portion Size Calculator: Amount of food per person. Salt Percentage Calculator: Salt as a percentage of the total weight. Course Credit Calculator: Terms left to graduate from credits needed and taken per term.
How to use the Food Waste Percentage Calculator
- Enter food wasted (0 or more).
- Enter total food (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Food wasted | A number | ≥ 0 |
| Total food | A number | > 0 |
Formula and method
Formula
waste % = wasted ÷ total × 100
IEEE-754 double precision; shown to the decimals indicated.
Use the same unit for both.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Food wasted = 120; Total food = 1500.
| Result | Value |
|---|---|
| Food waste | 8% |
Example 2
Inputs: Food wasted = 35; Total food = 400.
| Result | Value |
|---|---|
| Food waste | 8.75% |
The first line is the headline result (food waste). IEEE-754 double precision; shown to the decimals indicated.
Measuring waste
Weigh discards for a week and compare to what you bought or prepared. Use the same unit for both numbers. Tracking helps find the main causes such as over-ordering, spoilage and plate waste.
Context
Studies estimate that a significant share of food produced is lost or wasted worldwide, and an 8% rate for a kitchen is a useful benchmark to improve on. Wasted cannot exceed total.
How the result changes with food wasted
Holding every other input at the first worked example, this table changes only food wasted. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Food wasted | Food waste |
|---|---|
| 60 | 4% |
| 120 | 8% |
| 240 | 16% |
| 480 | 32% |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Total food: entering "0" shows "Total food must be greater than 0." beside that field and no result.
- Food wasted: entering "20" shows "Waste cannot exceed the total." beside that field and no result.
Choosing between the Food Waste Percentage Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Portion Size Calculator](/cooking/portion-size-calculator/) | total amount of food and people | Per person |
| [Salt Percentage Calculator](/cooking/salt-percentage-calculator/) | salt and total weight | Salt |
| [Course Credit Calculator](/education/course-credit-calculator/) | credits needed to graduate, credits completed and credits per term | Terms remaining |
| [Budget Calculator](/finance/budget-calculator/) | monthly income, housing and food | Left over each month |
| [Baker's Percentage Calculator](/cooking/baker-percentage-calculator/) | flour weight and other ingredient weights | Flour |
Background: cooking measurements
For baking, weight is more reliable than volume. A cup holds a fixed volume but its weight depends on the ingredient's density, and a cup of flour can vary by 20 to 30 grams depending on how it is scooped, so published gram-per-cup values for the same ingredient differ from site to site. Spoon and level flour if you must measure by volume.
Check which cup a recipe uses: the US cup is 236.588 mL, while a metric cup is 250 mL.
Assumptions and limitations
- Wasted cannot exceed total
Cooking times are guides. Use a food thermometer to confirm safe internal temperatures.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for total food and food wasted to confirm this.
Frequently asked questions
How can a restaurant cut waste?
Track it, adjust portions and plan menus around inventory.
Is the unit important?
Only that both numbers match.
What about edible vs inedible waste?
Decide whether to count peels and bones.
What does the Food Waste Percentage Calculator calculate?
Share of food that was wasted. It returns Food waste.
What formula does the Food Waste Percentage Calculator use?
waste % = wasted ÷ total × 100. Use the same unit for both.
What do I need to enter in the food Waste Percentage Calculator?
You enter Food wasted and Total food.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Wasted cannot exceed total.
What is an example of a food Waste Percentage result?
With food wasted 120 and total food 1500, the food waste is 8%.
Can I rely on this calculator for a decision?
Cooking times are guides. Use a food thermometer to confirm safe internal temperatures. For this calculator in particular: Wasted cannot exceed total.
Related calculators
- Portion Size Calculator — Amount of food per person.
- Salt Percentage Calculator — Salt as a percentage of the total weight.
- Course Credit Calculator — Terms left to graduate from credits needed and taken per term.
- Budget Calculator — Monthly income minus spending, and the share left over.
- Baker's Percentage Calculator — Each ingredient as a percentage of flour weight.
- College Cost Calculator — Projected total cost of study with yearly cost inflation.
- Test Score Percentage Calculator — Percentage score from correct answers out of total questions.
- Event Capacity Calculator — Guests that fit in a space at a space-per-person allowance you choose.
- Study Hours Calculator — Weekly study time from credits and hours per credit.
Sources
- OpenStax, Prealgebra 2e (Rice University): fractions, decimals, percents, ratios and rounding
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international inch 25.4 mm, avoirdupois pound 0.45359237 kg)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.