Laundry Load Size and Detergent Calculator
Find out how much laundry detergent to use based on load size, soil level, water hardness, and machine type.
Stop wasting detergent and get cleaner clothes.
How Much Laundry Detergent Do You Really Need?
Most people use 2–3 times more detergent than necessary. Excess detergent leaves residue on clothes, traps odors, builds up in your machine, and wastes money.
Why Less Is Often Better
Modern high-efficiency (HE) machines use far less water than older top-loaders. Using regular detergent in an HE machine, or simply using too much, causes:
- Excess suds that can damage the machine
- Clothes that feel stiff or sticky
- Residue that irritates sensitive skin
- A sour smell in the washing machine drum
Load Size Guide
| Load Size | Drum Fill | Weight |
|---|---|---|
| Small | 1/4 full | ~1.5 kg / 3 lbs |
| Medium | 1/2 full | ~3 kg / 6.5 lbs |
| Large | 3/4 full | ~4.5 kg / 10 lbs |
| Extra Large | Full (loose) | ~6 kg / 13 lbs |
Never pack the drum completely. Clothes need room to tumble.
Detergent Dosing Guide (Standard Liquid)
These are the figures the calculator uses, at medium water hardness.
| Load Size | Normal Soil | Heavy Soil | HE Machine, Normal Soil |
|---|---|---|---|
| Small | 20 ml / 4 tsp | 27 ml | 13 ml |
| Medium | 30 ml / 2 tbsp | 41 ml | 20 ml / 4 tsp |
| Large | 45 ml / 3 tbsp | 61 ml | 29 ml / 2 tbsp |
| Extra Large | 60 ml / 4 tbsp | 81 ml | 39 ml |
An HE machine takes about two thirds of the standard dose because it washes in far less water, so the same concentration needs less detergent. Soft water knocks another 20% off, hard water adds 20%. Those stack: a large load of lightly soiled clothing in an HE machine with soft water comes to 18 ml, less than half the 45 ml the same load would take in an old top-loader.
Water Hardness Matters
Soft water: about 20% less than the label says, which is what this calculator applies. Hard water: about 20% more. Calcium and magnesium in hard water bind to the surfactants before they ever reach your clothes, so part of the dose is spent softening the water rather than washing. If you do not know which you have, your kettle does. Heavy limescale means hard water.
Powder vs Liquid vs Pods
- Powder: Most economical, works best in warm/hot water
- Liquid: Best for cold water washing, good for pre-treating stains
- Pods/Capsules: Pre-measured, convenient, but usually more expensive per wash
- HE detergent: Essential for front-loaders and newer top-loaders, always look for the HE symbol
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.