Calculator
Detergent supply and cost per load calculator
This works out how long a bottle lasts and what each load costs, using the numbers printed on your own detergent label. It does not decide your dose for you. Your label and washer manual do that. The result updates as you type, and nothing leaves your device.
46 loads per bottle at the label dose
Worked example (shown when scripts are off): a 100 fl oz bottle, a 2 fl oz dose for 5 normal loads and a 3 fl oz dose for 1 heavy load a week. Weekly use is 5 x 2 + 1 x 3 = 13 fl oz, so the bottle lasts 100 / 13 = 7.7 weeks, or about 46 loads at 2.17 fl oz average.
Before you rely on this
- Use the dose on your own label and in your washer manual. More detergent does not clean better and can leave residue.
- Enter the size and the doses in the same unit, exactly as printed. If the label shows only a fill line on the cap, measure that line once with a kitchen measure.
- This is general planning information, not a cleaning recommendation.
How the calculator works
Weekly use is the number of normal loads times the normal dose, plus the number of heavy loads times the heavy dose. Weeks per bottle is the bottle size divided by weekly use. Loads per bottle is the bottle size divided by the average dose per load, rounded down because a partial load is not a load. Cost per load is the price divided by loads per bottle, and the monthly figure is the price divided by weeks per bottle, scaled by 52 weeks over 12 months.
If you fill in what you pour now, the calculator repeats the same sums with that amount in place of the label dose. The heavy dose is scaled by the same ratio, so the comparison stays fair. The point is to show what habitual extra pouring costs in money and in how often you buy a bottle.
Worked example
A bottle of 100 fluid ounces, a label dose of 2 for a normal load and 4 for a large one. You run 3 normal and 1 large load a week. Use is 3 x 2 + 1 x 4 = 10 per week, so the bottle lasts 10 weeks and covers 40 loads at an average of 2.5 per load. At a price of 15 dollars that is 0.38 dollars per load. If you actually pour double for normal loads, use rises to 20 per week, the bottle lasts 5 weeks and cost per load doubles.
Why the label dose matters
Washer and detergent makers publish dosing because too little can leave soil behind and too much can leave residue that clothes and the machine hold onto. High-efficiency machines use less water, so they are especially sensitive to suds. Using an HE-labeled detergent where the machine calls for one is a standard instruction in manufacturer guidance and in consumer energy advice. Residue and suds are also one reason clothes can smell after washing; the odor article linked below goes through the causes.
Limits
- Concentrated and regular formulas, pods, powders and sheets measure differently. For pods or sheets, enter the doses as 1 per load and the bottle size as the count in the box.
- Label doses often vary with water hardness, load size and soil. The calculator does not adjust for these. Follow the label.
- The monthly figure assumes the same pattern every week.
- Prices vary by store and pack. Use the price you actually paid.
Where this comes from
The arithmetic is a plain unit calculation and uses only numbers you enter. The advice to follow the label dose and to use detergent made for high-efficiency machines in those machines reflects what detergent and washer makers print in their instructions and what Energy Star clothes washer guidance says. The dose itself comes from your label, not from this page.