How this calculator works
A dilution ratio compares volumes. A 1:10 mix means one unit of concentrate for every ten units of water, so the finished volume is eleven units, not ten. That is the most common mistake: adding ten litres of water to one litre of concentrate makes eleven litres at a ratio of 1:10, but filling a ten litre container with one litre and topping up to the mark makes a slightly stronger 1:9 mix. This page uses the first convention, which is what product labels mean, and divides the target volume by one plus the ratio to find the concentrate.
Formula
concentrate = total volume / (1 + parts of water). water = total volume - concentrate. From two measured volumes: ratio = water / concentrate.
Worked example
To make 5 litres at 1:10, the concentrate is 5 / 11 = 0.4545 L, that is 454.5 mL, and the water is 4,545 mL. If you instead poured 500 mL of concentrate into 4,500 mL of water, the mix is 1:9, which is a little stronger than 1:10.
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Frequently asked questions
Is a 1:10 dilution the same as 10 percent?
No. A 1:10 ratio gives 1 / 11 = 9.1 percent concentrate. A 10 percent solution is a 1:9 ratio. For disinfectants, where the contact time and concentration matter, follow the label exactly.
How do I make a small amount?
Use the mix mode and enter the volume you actually need, even if it is a few hundred millilitres. Using a measuring cup or syringe marked in millilitres gives a far more accurate mix than estimating part-full caps.
Does the ratio work with ounces and gallons too?
Yes, because a ratio compares volumes in the same unit. The calculator accepts imperial units and converts them internally, so a 1:10 mix is the same proportion in either system.
What about ratios written the other way, such as 10:1?
Some products, such as certain sealers or fuel additives, are written concentrate first. Check the order on the label; if the bigger number comes first, the concentrate is the larger part and this calculator does not apply.