Before calculating 1:50 dilution, identify the two quantities being compared. 1 part concentrate to 50 parts water and 1 part concentrate in 50 parts total describe different mixtures. One is not inherently more accurate than the other; the correct calculation depends on the stated instruction.
The examples below use matching volume units and add the measured concentrate and water volumes. They are arithmetic examples, not recommended recipes for a particular shampoo, pesticide or cleaner.
Compare the two meanings
| Meaning of the instruction | Parts being mixed | With 100 mL concentrate | Concentrate's share of total volume |
|---|---|---|---|
| Concentrate : water = 1 : 50 | 1 concentrate + 50 water = 51 total | 5,000 mL water; 5,100 mL total | 1/51 ≈ 1.96% |
| Concentrate : total = 1 : 50 | 1 concentrate + 49 water = 50 total | 4,900 mL water; 5,000 mL total | 1/50 = 2% |
The percentages describe the original concentrate's share of the mixture by volume. They do not identify the concentration of an active ingredient within the product.
When a label gives an explicit dose, such as an amount of concentrate per liter of water, use that stated basis. If it gives only '1:50' without explaining the basis, check the manufacturer's instructions before mixing. EPA introduction to pesticide labels
Example 1: a 1:50 concentrate-to-water ratio, 1L total
Divide 1,000 mL into 51 parts:
- Concentrate: 1,000 ÷ 51 ≈ 19.61 mL
- Water: 1,000 × 50 ÷ 51 ≈ 980.39 mL
These are rounded to two decimal places. Measuring 20 mL concentrate and 980 mL water instead gives a 1:49 concentrate-to-water ratio. Choose measuring equipment and precision that match the product instructions.
Example 2: adding concentrate to 1L of water
Here, the water amount is fixed at 1,000 mL:
- Concentrate: 1,000 ÷ 50 = 20 mL
- Calculated total: 1,000 + 20 = 1,020 mL
The finished amount is greater than 1L. 'Start with 1L of water' and 'make 1L total' are different inputs.
Example 3: 1 part concentrate in 50 parts total
If the instruction means concentrate : total = 1 : 50, a 1,000 mL total contains 20 mL concentrate, with 980 mL water under the additive-volume calculation. Expressed as concentrate to water, this is 1:49.
For instructions requiring a precise final volume, follow their method for making up to that volume rather than assuming measured liquid volumes always add exactly.
Entering the ratio in the app
The Dilution Ratio Calculator compares concentrate and water in its two ratio fields.
| Intended calculation | Ratio fields | Mode and amount |
|---|---|---|
| Concentrate:water 1:50, 1L total | Concentrate 1, water 50 | Total amount; 1,000 mL |
| Concentrate:water 1:50, 1L water | Concentrate 1, water 50 | Material/water amount; water 1,000 mL |
| Concentrate:total 1:50, 1L total | Concentrate 1, water 49 | Total amount; 1,000 mL |
The app calculates quantities from your entries; it does not select the product's mixing ratio or mixing order. For another worked example, see calculating 1:500 from total volume or water amount.