Percent Solution Calculator
Calculate a percent concentration — weight/volume, weight/weight or volume/volume — from the amounts, or the amount needed for a target percentage.
Percent concentration the way a lab or pharmacy writes it.
How the percent solution calculator works
Percent solutions come in three flavours. w/v is grams of solute per 100 mL of solution (a 0.9% saline has 0.9 g per 100 mL); w/w is grams per 100 g of solution; v/v is milliliters per 100 mL (70% alcohol). Pick the type, enter the solute amount and the total, and the calculator gives the percentage; in Detailed mode enter a target percentage to see how much solute a volume needs.
Formula: % = solute ÷ total × 100
Worked examples
| Inputs | Concentration | Note |
|---|---|---|
| 9 g NaCl in 1,000 mL (normal saline) | 0.9% | 0.9% w/v |
| 70 mL ethanol made to 100 mL | 70% | 70% v/v |
| 25 g sugar in 200 g of syrup | 12.5% | 12.5% w/w |
FAQFrequently asked questions
What does 0.9% saline mean?
0.9 g of sodium chloride in every 100 mL of solution (w/v) — 9 g per liter.
How do I convert w/v percent to molarity?
Percent w/v × 10 gives g/L; divide by the molar mass. 0.9% NaCl = 9 g/L ÷ 58.44 = 0.154 M.
Why is v/v alcohol not the same as w/w?
Because ethanol is less dense than water: 70% v/v is about 62% w/w.
Is the total the solute plus solvent?
For w/v and v/v it is the final solution volume; for w/w the total mass of solution (solute plus solvent).
Where these figures come from
- IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
- NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
- NIST Chemistry WebBook — thermochemical data
- National Institute of Standards and Technology — the US measurement and reference-data authority
Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.