Mixing concentrates the right way
Cleaning concentrates, garden products, car shampoos and photo chemicals all come with a dilution instruction, usually written as a ratio such as 1:10 or 1:64. Getting it right matters: too weak and the product does not work, too strong and you waste money, leave residue or damage the surface. This calculator handles both ways dilutions are written, as a mix ratio or as a target concentration.
Mode 1: a mix ratio
A ratio of 1:X means one part concentrate for X parts water, so the mix has X + 1 parts in total.
- Concentrate = total volume ÷ (X + 1).
- Water = total volume − concentrate.
Mode 2: concentrations (C1V1 = C2V2)
When you know the strength of the starting product and the strength you want, use the dilution equation: the amount of active ingredient stays the same, only the volume grows.
- Concentrate = total volume × target strength ÷ starting strength.
- Water = total volume − concentrate.
Worked example: a 1:10 spray bottle
You want to fill a 32 fl oz spray bottle with a cleaner diluted 1:10.
- Total parts: 1 + 10 = 11.
- Concentrate: 32 ÷ 11 = 2.91 fl oz, a little under 6 tablespoons.
- Water: 32 − 2.91 = 29.09 fl oz.
- The concentrate makes up 9.09 percent of the mix.
With concentrations instead: diluting a 70 percent solution to 10 percent in the same bottle takes 32 × 10 ÷ 70 = 4.57 fl oz of solution and 27.43 fl oz of water.
Concentrate for a 32 fl oz bottle
| Ratio | Concentrate | Water |
|---|---|---|
| 1:4 | 6.40 fl oz | 25.60 fl oz |
| 1:10 | 2.91 fl oz | 29.09 fl oz |
| 1:16 | 1.88 fl oz | 30.12 fl oz |
| 1:32 | 0.97 fl oz | 31.03 fl oz |
| 1:64 | 0.49 fl oz | 31.51 fl oz |
| 1:128 | 0.25 fl oz | 31.75 fl oz |
For a full gallon, multiply the concentrate figures by four: 1:64 takes about 2 fl oz, or a quarter cup, per gallon.
Ratio or fraction?
Most product labels use “parts to parts”: 1:10 is one part product, ten parts water. Some labs and a few labels use “parts per total”, where 1:10 means one part product in ten parts of finished mix, which is slightly stronger. If a label says “1 oz per gallon” instead, that is a dose rather than a ratio: 128 fl oz per gallon makes it about 1:127.
Handy volume equivalents
- 1 tablespoon = 0.5 fl oz, and 1 teaspoon = 1/6 fl oz.
- 1 cup = 8 fl oz, 1 quart = 32 fl oz, 1 gallon = 128 fl oz.
- 1 fl oz = 29.57 ml.
Safety first
- Never mix bleach with ammonia or with acids such as vinegar or some toilet bowl cleaners: they release toxic gases.
- Add concentrate to water, not water to concentrate, especially with acids and strong alkalis, to limit splashing.
- Label the bottle with the product and the ratio you used, and keep diluted products out of reach of children.
- Follow the manufacturer’s ratio for disinfecting: a weaker mix may not kill germs within the stated contact time.