How do you calculate the concentration of a solution in g/L?

Divide the mass of solute in grams by the volume of solution in litres — or by millilitres and multiply by 1,000. 2.5 g in 250 mL is 2.5 ÷ 250 × 1,000 = 10 g/L. Enter the mass and volume and the page converts to the other units too.

What does a 0.9% or 5% solution mean?

Percent w/v is grams of solute per 100 mL of solution. 0.9% saline has 0.9 g of NaCl per 100 mL (9 g/L); 5% dextrose has 5 g of glucose per 100 mL (50 g/L). The page shows the w/v figure for any mass and volume.

How do I convert ppm to mg/L or g/L?

For dilute water solutions, 1 ppm = 1 mg/L, so 250 ppm is 250 mg/L = 0.25 g/L. Going the other way, g/L × 1,000 = ppm. The relation breaks down for concentrated solutions, where ppm by mass and mg per litre differ.

How do I turn g/L into molarity?

Divide by the solute's molar mass. 50 g/L of glucose (180.16 g/mol) is 50 ÷ 180.16 = 0.278 mol/L. The molarity calculator's grams mode does this directly.

How do I make a 5% salt solution?

Weigh 5 g of salt and add water up to 100 mL of finished solution. Dissolving 5 g in 100 mL of water gives slightly less than 5% w/v, because the volume grows as the salt goes in.

What is the difference between w/v, w/w and v/v percent?

w/v is grams per 100 mL of solution, which this page uses; w/w is grams per 100 g of solution; v/v is millilitres per 100 mL, the basis of a drink's ABV.

Solution Concentration Calculator (g/L, % w/v, mg/mL, ppm)

Mass concentration of a solution from solute mass and solution volume, in g/L, percent w/v, mg/mL and ppm.

Inputs

Solute mass(g)

0 g1,000,000,000 g

Solution volume(mL)

0.1 mL1,000,000,000 mL

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Concentration

50 g/L

Working: 5 g ÷ 100 mL × 1,000 = 50 g/L
Percent (w/v): 5% — grams per 100 mL
mg/mL: 50 mg/mL (the same number as g/L)
ppm (mg/L): 50,000 ppm, treating the solution as water
Solute mass: 5 g
Solution volume: 100 mL

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What each Solution Concentration input means

Solute mass: The mass of the dissolved substance, in grams. Milligrams ÷ 1,000 are grams.
Solution volume: The final volume of the solution in millilitres — what the flask is made up to, not the water added.

Solution Concentration formula

g/L = grams of solute ÷ millilitres of solution × 1,000 · % w/v = grams ÷ millilitres × 100 · mg/mL = g/L · ppm ≈ mg/L for dilute aqueous solutions

\%\ (\text{w/v}) = \frac{m_{\text{solute}}\ (\text{g})}{V_{\text{solution}}\ (\text{mL})} \times 100

Not every concentration is a molarity. Medicine, food and water quality describe solutions by mass of solute per volume of solution: grams per litre, milligrams per millilitre (the same number), percent weight-per-volume (grams per 100 mL — a 0.9% saline drip is 0.9 g of NaCl in every 100 mL), and parts per million, which for dilute water solutions is milligrams per litre because a litre of water weighs a million milligrams. The page takes the solute's mass and the solution's volume and expresses the same ratio in all four, showing the arithmetic. To go from any of these to molarity, divide g/L by the molar mass — the molarity calculator has a grams mode for exactly that.

Solution Concentration worked example

5 g of glucose made up to 100 mL of solution: 5 ÷ 100 × 1,000 = 50 g/L, which is 50 mg/mL and, as grams per 100 mL, 5% w/v — the strength of a standard dextrose infusion. In ppm that is 50,000 mg/L, far too concentrated for ppm to be a sensible unit; ppm is for trace amounts, like 8 mg of dissolved oxygen in a litre of river water, 8 ppm.

Where the Solution Concentration calculator can give the wrong answer

Volume is of the finished solution, not of the solvent. 5 g in 100 mL of water is slightly more than 100 mL of solution and slightly under 5% w/v.
ppm = mg/L assumes the solution's density is 1 g/mL, true for dilute aqueous solutions and false for concentrated ones or other solvents; strictly ppm is by mass (mg per kg).
Percent solutions come in three kinds — w/v (g per 100 mL), w/w (g per 100 g) and v/v (mL per 100 mL) — and a label that just says '5%' is ambiguous. This page is w/v.
Mass concentration says nothing about moles. 50 g/L of glucose (0.28 M) and 50 g/L of NaCl (0.86 M) are very different chemically; use the molar mass to convert.
For solids that dissolve with a large volume change, or gases, the mass-per-volume figure should be taken from the solution as prepared, not calculated from the water added.

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Solution Concentration reference table

The same concentration in four units
% w/v	g/L	mg/mL	ppm (mg/L, in water)
10%	100	100	100,000
1%	10	10	10,000
0.9% (normal saline)	9	9	9,000
0.1%	1	1	1,000
0.01%	0.1	0.1	100
0.0001%	0.001	0.001	1

Source: OpenStax Chemistry 2e, §3.4: % w/v is grams per 100 mL; ppm is mg per litre for dilute aqueous solutions

Solution Concentration FAQ

: Divide the mass of solute in grams by the volume of solution in litres — or by millilitres and multiply by 1,000. 2.5 g in 250 mL is 2.5 ÷ 250 × 1,000 = 10 g/L. Enter the mass and volume and the page converts to the other units too.
: Percent w/v is grams of solute per 100 mL of solution. 0.9% saline has 0.9 g of NaCl per 100 mL (9 g/L); 5% dextrose has 5 g of glucose per 100 mL (50 g/L). The page shows the w/v figure for any mass and volume.
: For dilute water solutions, 1 ppm = 1 mg/L, so 250 ppm is 250 mg/L = 0.25 g/L. Going the other way, g/L × 1,000 = ppm. The relation breaks down for concentrated solutions, where ppm by mass and mg per litre differ.
: Divide by the solute's molar mass. 50 g/L of glucose (180.16 g/mol) is 50 ÷ 180.16 = 0.278 mol/L. The molarity calculator's grams mode does this directly.
: Weigh 5 g of salt and add water up to 100 mL of finished solution. Dissolving 5 g in 100 mL of water gives slightly less than 5% w/v, because the volume grows as the salt goes in.
: w/v is grams per 100 mL of solution, which this page uses; w/w is grams per 100 g of solution; v/v is millilitres per 100 mL, the basis of a drink's ABV.