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What does this calculator estimate?
A percent solution calculator converts solute mass and solution amount into percent concentration. Enter the solute mass and choose w/v (volume-based) or w/w (mass-based) to calculate.
- w/v % = g solute ÷ mL solution × 100
- w/w % = g solute ÷ g solution × 100
- Percent = parts per hundred
What percent solutions mean
Percent concentration states how much solute is in 100 parts of solution. w/v (weight/volume) is standard for aqueous solutions — 5 g in 100 mL is 5% — while w/w (weight/weight) is used when everything is weighed.
Limitations to watch for
The two conventions are not interchangeable: 5% w/v ≠ 5% w/w because water density differs. The denominator is total solution (solute + solvent), not solvent alone. Very dilute (<0.1%) or concentrated solutions may be better in ppm or molarity.
How to use it in practice
For w/v, weigh the solute and dissolve to the final volume mark. For w/w, weigh both components and use total mass. Read labels carefully — '5%' in pharmacy, food, and industry can mean different conventions.
['Enter the solute mass in grams.', 'Choose w/v (solution volume in mL) or w/w (solution mass in g).', 'Enter the total volume or mass; the tool computes the percent.']
What percent solution means
A percent solution is the amount of solute per 100 parts of solution: 5% w/v means 5 grams per 100 mL. Percent solutions appear in lab work, cleaning dilutions, and medication preparation — the concentration drives the dose or effect.
Weight/volume vs. volume/volume
% w/v is grams per 100 mL (common for solids in liquid); % v/v is mL per 100 mL (for liquid in liquid). A 70% v/v alcohol solution is 70 mL alcohol per 100 mL. Mixing the conventions produces errors — the calculator is explicit about which one you are using.
Making a percent solution
To make 500 mL of 2% w/v salt solution: 2 g per 100 mL × 5 = 10 g of salt, then add water to a final volume of 500 mL. The solute is weighed, dissolved, and brought to volume — not simply added to 500 mL of water.
Dilution from stock
A concentrated stock is diluted with the C1V1 = C2V2 equation: 100 mL of 20% stock diluted to 200 mL gives 10%. The percent-solution calculator pairs with the dilution calculator for serial work.
A worked example
To prepare 250 mL of 4% w/v solution: 4 g per 100 mL × 2.5 = 10 g solute, brought to 250 mL total volume. The calculator returns the solute mass and the final volume instructions.
How this calculator works
Formula
w/v percent = (solute mass in g ÷ solution volume in mL) × 100. w/w percent = (solute mass ÷ solution mass) × 100.
Worked example
5 g of NaCl dissolved to 100 mL of solution = 5% w/v. 5 g of salt mixed into 100 g of total mixture = 5% w/w.
Assumptions to verify
- The solute dissolves completely.
- The chosen convention (w/v or w/w) matches the application.
- The denominator is the total solution amount.
Frequently asked questions
What is a percent solution?
Solute per 100 parts of solution — as mass/volume (w/v) or mass/mass (w/w). 5 g in 100 mL = 5% w/v.
What is the difference between w/v and w/w?
w/v uses solution volume in the denominator (g/mL × 100); w/w uses total solution mass (g/g × 100).
How do I make a 5% w/v solution?
Dissolve 5 g of solute and bring the total volume to 100 mL with solvent.
Which convention should I use?
w/v for aqueous solutions and most lab work; w/w when all components are weighed (ointments, alloys, powders).
Does 5% w/v equal 5% w/w?
No — 5 g in 100 mL ≈ 4.76% w/w because 100 mL of water weighs ~100 g, but the solute adds mass.
What is ppm?
Parts per million — 1 ppm = 1 mg/L ≈ 0.0001%. Use it for very dilute solutions.
How does percent relate to molarity?
Percent is mass-based; molarity is mole-based. Molarity = (percent w/v ÷ 100) × density ÷ molar mass.
What is the difference between w/v and v/v?
w/v is grams per 100 mL (solid in liquid); v/v is mL per 100 mL (liquid in liquid).
How do I make a percent solution?
Weigh the solute for the target percent and volume, dissolve, then bring to final volume.
How do I dilute a stock solution?
Use C1V1 = C2V2 to find the stock volume, then add solvent to the final volume.
Cite this tool
BoringToolsKit. “Percent Solution Calculator.” boringtoolskit.com/percent-solution-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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