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Percent Solution Calculator

Find out how much of a substance to dissolve, and how much liquid to add, for a weight/volume, weight/weight or volume/volume percent solution.

Level: Grades 6–7

  • Common Core standard 6.RP.A.3.cFind a percent of a quantity as a rate per 100 (e.g., 30% of a quantity means 30/100 times the quantity); solve problems involving finding the whole, given a part and the percent.
Printable worksheet

Percent Solution Calculator

Know the answer you need? Pick an input to work backward.

Inputs
Solution type

w/v: grams of the substance per 100 mL of solution. w/w: grams per 100 g of solution. v/v: milliliters per 100 mL of solution.

Result

Solute to weigh out

50 g

Dissolve 50 g of solute and make it up to 500 mL for 10% w/v.

Then add solvent up to a final volume of
500 mL
Concentration in grams per liter
100 g/L
Concentration in milligrams per milliliter
100 mg/mL
Concentration
10% w/v

See the step-by-step solution ↓

Step-by-step solution

  1. Take that percent of the volume in mL. The answer is the grams of solute to weigh out

    10%100×500 mL=50 g

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find out exactly how much of a substance to dissolve, and how much liquid to add, to make a percent solution. A percent tells you how much of the dissolved substance (the solute) is in every 100 parts of the mixture. The tricky part is that there are three kinds. Weight/volume (w/v) means grams per 100 mL. Weight/weight (w/w) means grams per 100 g. Volume/volume (v/v) means milliliters per 100 mL.

This calculator turns a target percent and a final amount into a recipe. Choose the type, then enter the strength and how much solution you want. It tells you how much solute to weigh or measure, and how much solvent (the liquid it's mixed into) to add. It also explains how to top up liquids to the right final volume.

Where it's used

Why this math matters outside the classroom:

  • Biology labs. A teaching assistant makes 500 mL of 10% w/v sugar solution by dissolving 50 g and topping up to 500 mL.
  • Saline. A lab technician dissolves 9 g of salt to 1 L to get a 0.9% w/v solution.
  • Cleaning mixes. A cleaner measures 300 mL of concentrate made up to 1 L for a 30% v/v mixture.
  • Brining. A cook dissolves 50 g of salt in 950 g of water to make 1 kg of 5% w/w brine.
  • Agar plates. Students weigh 7.5 g of agar for 500 mL of a 1.5% w/v medium.

Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.RP.A.3.c. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Choose the solution type. Use w/v for a solid dissolved to a set volume, w/w when you weigh everything, or v/v for one liquid mixed into another.
  2. Enter the strength you want, in percent.
  3. Enter how much finished solution you need, by weight or volume, in the unit you'll measure with.
  4. Weigh or measure the solute, then add solvent as shown.

What the inputs mean

Target concentration
Use the percent as written in your instructions, such as 0.9 for 0.9% saline or 70 for 70% alcohol.
Final volume of solution
This is the volume of the finished solution, not the amount of solvent you add.

Formula and method

w/v: solute (g) = percent ÷ 100 × final volume (mL)
w/w: solute (g) = percent ÷ 100 × final mass (g); solvent = final mass − solute
v/v: solute (mL) = percent ÷ 100 × final volume (mL)
1% w/v = 1 g per 100 mL = 10 g/L

Every percent is an amount per 100. So the amount of solute is the percent divided by 100, times the size of your batch. The only thing that changes between the types is which parts you weigh and which you measure by volume.

For w/w, both parts are weights, so the solvent is whatever weight is left. For w/v and v/v, you dissolve the solute first and then top up to the final volume. That's because mixed liquids don't always add up exactly. For example, 50 mL of ethanol and 50 mL of water make a little less than 100 mL.

Worked example

How do you make 1 L of 0.9% w/v sodium chloride solution (normal saline strength)?

  1. Change the volume to milliliters: 1 L × 1,000 = 1,000 mL.
  2. Solute: 0.9 ÷ 100 × 1,000 mL = 9 g.

Result: Dissolve 9 g of sodium chloride in some water. Then add water until the total volume is 1,000 mL. That's 9 g/L.

Understanding the result

You can read a w/v percent directly as grams per 100 mL. Multiply it by 10 to get grams per liter. So a 5% w/v solution has 50 g/L.

The same number means different amounts under different types. A 10% w/w solution and a 10% w/v solution aren't the same, unless the solution weighs exactly 1 g per mL (its density).

Assumptions and limitations

  • The solute is pure. If it isn't, or it contains bound water (water of hydration), adjust for that yourself.
  • For w/v and v/v, you top up the solution to the final volume in a measuring flask or cylinder.
  • It doesn't convert between percent types. That needs the solution's density.
  • It's a calculation aid, not a replacement for a lab's or pharmacy's approved procedures.
  • For strength in moles per liter, use a molarity calculator. To water down a stronger stock solution, use a dilution calculator.

Frequently asked questions

What does 10% w/v mean?

It means 10 grams of solute in every 100 mL of finished solution, which is 100 g per liter. To make 250 mL, you'd dissolve 25 g and top it up to 250 mL.

Why not just add the solute to the full volume of solvent?

The solute takes up some space. Adding it to 1,000 mL of water gives a bit more than 1,000 mL of solution, so it ends up slightly weaker. Topping up to the final volume avoids that.

How do I make 70% alcohol from pure alcohol?

For 100 mL of 70% v/v, measure 70 mL of alcohol and add water up to 100 mL. Starting from a weaker stock, such as 95%, is a dilution problem instead.

Is w/w the same as mass percent?

Yes. Weight/weight percent, mass percent and percent by mass all mean grams of solute per 100 g of solution.

How this calculator is checked

Method: Definitions of percent concentration: w/v = g per 100 mL, w/w = g per 100 g, v/v = mL per 100 mL of solution. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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