Dilution Ratio Calculator

Work out how much concentrate and water to mix for any dilution ratio.

Result

100.00 mL
400.00 mL
1 : 4

How it is calculated

A ratio written 1 : N means 1 part concentrate to N parts water, so the mix has N + 1 parts in total. Given the final volume, concentrate = total ÷ (N + 1) and water = total − concentrate. The total volume is in millilitres and both answers are in mL. N cannot be negative and the total must be above zero. The total is the finished volume, not the amount of concentrate you start with. The tool assumes volumes simply add up, which is a good approximation for most cleaning and garden products.

Worked example

You want 500 mL of a 1 : 4 solution. Parts: 1 + 4 = 5. Concentrate: 500 ÷ 5 = 100.00 mL. Water: 500 − 100 = 400.00 mL. Check: 100 : 400 reduces to 1 : 4.

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Common mistakes

  • Reading 1 : 4 as 1 part in 4 total. Here it means 1 part concentrate plus 4 parts water, 5 parts in all, so the concentrate is 20% of the mix, not 25%.
  • Entering the concentrate volume as the total. The total is what you end up with after adding water.
  • Using litres instead of millilitres. 2 litres must be entered as 2000.
  • Mixing up the order. 1 : 4 and 4 : 1 are very different strengths, so check which side the product label puts the concentrate on.

About this calculator

This calculator splits a target total volume into concentrate and water for a chosen dilution ratio expressed as 1:N — one part concentrate to N parts water — solving concentrate = total/(N+1) and water = total − concentrate.

Cleaning staff, gardeners mixing fertilizer or pesticide, and bartenders or lab technicians preparing solutions use it to hit label-specified ratios accurately instead of eyeballing pours.

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Comments (1)

  • Editorial team

    If a label gives a percentage instead of a ratio, convert it first: a 2 percent solution is 1 part concentrate in 50 parts total, so enter 49 as the ratio. The general rule is N = 100 ÷ percent − 1. It is worth mixing a small test batch in a measuring jug before scaling up. Which label formats do you find awkward? Tell us what wording you would like supported.

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