PPM Dilution Calculator
Use this ppm dilution calculator to dilute a stock measured in parts per million down to a target ppm. Enter the stock ppm, the ppm you want, and the final volume — it returns the stock and water to combine.
Enter the stock ppm, the ppm you want, and the final volume to get the stock and water to combine.
How to dilute a ppm solution
Parts per million behaves like any other concentration, so the dilution equation applies with ppm in place of molarity:
Solving for the stock volume gives:
V₂ is the final volume, and the water to add is V₂ − V₁. To move between percent and ppm, remember 1% = 10,000 ppm — convert both stock and target to the same unit first.
Worked example
Making 1 L of 50 ppm from a 1000 ppm stock: V₁ = (50 × 1000) ÷ 1000 = 50 mL of stock plus 950 mL of water — a 20× dilution.
Common ppm targets by application
The right target ppm depends on what it's for — these are typical ranges:
| Application | Typical target ppm |
|---|---|
| Drinking water chlorine residual | 0.2–2 ppm |
| Pool free chlorine | 1–3 ppm |
| Spa/hot tub free chlorine | 2–4 ppm |
| Hydroponic nutrient solution (TDS) | 500–1,500 ppm |
| Aquarium ammonia (safe threshold) | < 0.25 ppm |
Related tools
For ppm ⇆ mg/L ⇆ percent conversions and the solute mass for a target ppm, use the ppm calculator. To dilute in percent instead, use the percentage dilution calculator.
Frequently asked questions
›How do I make a 50 ppm solution from 1000 ppm?
Use V₁ = (target ppm × V₂) ÷ stock ppm. For 1 L of 50 ppm from a 1000 ppm stock: V₁ = (50 × 1000) ÷ 1000 = 50 mL of stock topped up with 950 mL of water. That is a 20× dilution.
›How do I convert percent to ppm?
Multiply percent by 10,000: 1% = 10,000 ppm, so 0.5% = 5,000 ppm and 100 ppm = 0.01%. To go the other way, divide ppm by 10,000. This lets you dilute between percent and ppm stocks as long as you convert to one unit first.
›Is 1 ppm the same as 1 mg/L?
For dilute water-based solutions, yes — 1 ppm ≈ 1 mg/L because 1 litre of water weighs about 1 kg. This calculator works directly in ppm, so you can enter your stock and target ppm without converting.
›Is this ppm dilution calculator free?
Yes. It runs entirely in your browser, needs no sign-up, and never sends your numbers to a server.
›What ppm should hydroponic nutrient solution be?
Most leafy greens run 500–1000 ppm (TDS) and fruiting crops like tomatoes run 1000–1500 ppm, but it varies by nutrient brand and growth stage — check your feeding chart and adjust from there.
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