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Percent Solution Calculator

Chemistry

Calculate weight by volume (w/v), weight by weight (w/w), and volume by volume (v/v) percent solutions. Find grams needed to make a percent solution of any volume.

5 g
g
100 mL
mL

Percent Solution (% w/v)

5
Concentration (g/L)
50
Grams per 100 mL
5

This calculator computes your Percent Solution (% w/v), Concentration (g/L), Grams per 100 mL from the values you enter.

Inputs
Mass of SoluteVolume of Solution
Outputs
Percent Solution (% w/v)Concentration (g/L)Grams per 100 mL

What is a Percent Solution?

The Percent Solution Calculator computes the weight-by-volume concentration (% w/v) of a solution from the mass of solute (in grams) and the final volume of solution (in mL). It returns the % w/v concentration, the equivalent concentration in g/L, and grams per 100 mL — the three most common ways to express percent solution concentration in a single calculation.

Percent solution is the most intuitive concentration expression in everyday chemistry, pharmacy, and food science. A 5% w/v solution contains 5 grams of solute in every 100 mL of solution — a definition that is easy to prepare without knowing the molar mass, which makes it widely used for substances with uncertain or variable molecular weights (biological extracts, food additives, industrial chemicals).

The % w/v definition is the standard in the Indian Pharmacopoeia (IP) for injectable solutions, eye drops, and syrups. Normal saline (0.9% NaCl), 5% dextrose IV, and 70% IPA disinfectant are all specified as percent concentrations rather than molarity. Converting between percent solutions and molarity requires the molar mass — use the Concentration Calculator for this. The Percent Solution Calculator handles the preparatory question: given a mass and volume, what is the percent concentration?

The related % w/w (weight by weight) concentration is used when solutions are weighed rather than volumetrically measured — this is important for concentrated solutions (like 98% H₂SO₄) where the density is very different from 1 g/mL, making % w/v and % w/w significantly different. For dilute aqueous solutions (< ~5%), water's density is close to 1 g/mL, so % w/v and % w/w are nearly equal and the distinction is rarely important.

In India's school curriculum, percent solutions appear in NCERT Class 12 Chapter 2 and are a standard practical skill in food testing (FSSAI food standards specify % w/v for preservatives and additives) and water treatment (NaOCl concentration in % for disinfection). For the dilution step — converting a concentrated percent solution to a working concentration — use the Solution Dilution Calculator.

How to use this Percent Solution calculator

  1. Weigh your solute — measure the mass of solute to dissolve. For 5% NaCl (to make 100 mL), you will need 5 g.
  2. Enter Mass of Solute — type the mass in grams into the Mass of Solute field. For 5 g, enter 5.
  3. Enter Volume of Solution — type the final volume of the solution (after dissolving and making up to volume) into the Volume of Solution field in mL. For a 100 mL flask, enter 100.
  4. Read Percent Solution (% w/v) — the highlighted result shows the concentration. If you dissolved 5 g in 100 mL, you get 5% w/v.
  5. Read Concentration (g/L) — note the g/L value for reporting or for comparison against standards. 5% = 50 g/L = 50,000 mg/L.
  6. Check grams per 100 mL — this equals % w/v numerically. For dilution to a lower percent, use the Solution Dilution Calculator with concentrations in % as C₁ and C₂.

Formula & Methodology

Percent solution (% w/v) formula:

> % w/v = (mass of solute in g ÷ volume of solution in mL) × 100

Equivalent forms:

> g/L = (mass of solute in g ÷ volume of solution in mL) × 1000 = % w/v × 10

> g per 100 mL = % w/v (numerically identical)

To convert % w/v to molarity:

> Molarity (M) = (% w/v × 10) ÷ molar mass (g/mol)

Worked example 1 — Normal saline preparation:

Prepare 500 mL of 0.9% w/v NaCl:
- Mass of NaCl = 0.9 ÷ 100 × 500 = 4.5 g
- Dissolve 4.5 g NaCl in water and make up to 500 mL
- Molarity: 0.9% × 10 ÷ 58.44 = 0.154 M NaCl (isotonic)

Worked example 2 — Glucose IV concentration verification:

A 5% dextrose (glucose, MW = 180.16 g/mol) IV bag contains 25 g in 500 mL:
- % w/v = (25 ÷ 500) × 100 = 5% ✓
- g/L = 50 g/L
- Molarity = 50 ÷ 180.16 = 0.278 M glucose

Worked example 3 — Bleach disinfection solution (FSSAI/hospital context):

Commercial bleach = 4% w/v NaOCl. To prepare 1 litre of 0.5% NaOCl for surface disinfection:
- C₁V₁ = C₂V₂: V₁ = (0.5 × 1000) ÷ 4 = 125 mL bleach + 875 mL water
- Verify: (125 × 4%) ÷ 1000 = 0.5% NaOCl ✓
- Use the Solution Dilution Calculator to compute this directly

Frequently Asked Questions

A percent solution expresses concentration as the amount of solute per 100 units of solution. Weight by volume (% w/v) is the most common: grams of solute per 100 mL of solution. Weight by weight (% w/w) is grams of solute per 100 g of solution. Volume by volume (% v/v) is mL of solute per 100 mL of solution. The Percent Solution Calculator computes % w/v (the lab standard for dissolved solids) from mass and volume inputs.
% w/v (weight per volume percent) = (mass of solute in grams ÷ volume of solution in mL) × 100. For example, 5 g of NaCl dissolved in 100 mL of solution = 5% w/v NaCl. One 'percent' w/v means 1 g of solute per 100 mL of solution = 10 g/L. This is the standard expression for drug concentrations in Indian Pharmacopoeia (IP) for injections, syrups, and eye drops.
% w/v (g solute per 100 mL solution) is used for solid solutes dissolved in liquid solvents — the most common lab expression. % w/w (g solute per 100 g solution) is used when the solution is weighed rather than volumetrically measured, and is required for very precise work or concentrated solutions where density deviates significantly from 1 g/mL. % v/v (mL solute per 100 mL solution) is used for liquid solutes in liquid solvents, such as alcohol in water. For dilute aqueous solutions, % w/v ≈ % w/w because water density ≈ 1 g/mL.
Molarity (M) = (% w/v × 10) ÷ molar mass. The factor 10 converts from g per 100 mL to g per litre. For example, 5% w/v NaCl: M = (5 × 10) ÷ 58.44 = 50 ÷ 58.44 = 0.856 M. Alternatively, g/L = % w/v × 10, then M = g/L ÷ molar mass. Use the Concentration Calculator for the mass-molar mass-volume route to molarity.
Common solutions in Indian hospital practice: Normal Saline = 0.9% NaCl (w/v), 5% Dextrose (D5W) = 5% glucose (w/v), 25% Dextrose (for hypoglycaemia) = 25% glucose (w/v), 3% H₂O₂ (hydrogen peroxide, antiseptic) = 3% w/v, 70% Isopropyl Alcohol (IPA) = 70% v/v. These are standardised per National List of Essential Medicines (NLEM) and are prepared using w/v or v/v definitions depending on whether the solute is solid or liquid.
Commonly encountered in Indian healthcare and lab settings: Betadine (povidone-iodine) = 10% w/v; Dettol (chloroxylenol) solution = 4.8% w/v; Savlon (chlorhexidine + cetrimide) = 0.5% + 0.5% w/v; 70% ethanol or IPA for surface disinfection = 70% v/v; bleach solutions for instrument disinfection = 0.5% or 1% sodium hypochlorite (from household bleach which is 3–5% NaOCl, diluted using C₁V₁ = C₂V₂).
Dissolve 10 g of NaCl (table salt) in enough water to make 100 mL of solution (not in 100 mL of water — the final volume must be 100 mL). This gives 10% w/v NaCl. For 500 mL: dissolve 50 g NaCl and make up to 500 mL. Molarity: 10% NaCl = (10 × 10) ÷ 58.44 = 1.71 M. In Indian science fairs and school labs, saturated NaCl is about 26% w/v (density ~1.2 g/mL).
Enter the mass of solute in grams in the Mass of Solute field, and the final volume of solution in mL in the Volume of Solution field. The calculator outputs the % w/v concentration, g/L (same as % w/v × 10), and grams per 100 mL (which equals % w/v numerically). The steps panel shows the division clearly.
The most common glucose (dextrose) IV infusions used in India are 5% (50 g/L), 10% (100 g/L), and 25% (250 g/L). The 5% solution is approximately isotonic (274 mOsm/L) and is used for hydration. The 25% solution is hypertonic and is used in emergency treatment of hypoglycaemia. Doses are prescribed in mg/kg/hour or mL/hour, requiring back-conversion from percent to grams per mL: 5% = 0.05 g/mL = 50 mg/mL.
Percent by mass (w/w) and percent by volume (v/v) are introduced in NCERT Class 12 Chemistry Chapter 2 (Solutions) alongside molarity and molality. Percent by weight/volume (% w/v) is taught in pharmacy and biology courses. JEE and NEET problems on solutions may require converting between % w/w, molarity, and molality — the Percent Solution Calculator handles the % w/v to g/L step.
g/L = % w/v × 10. This is because % w/v is grams per 100 mL, and there are 10 × 100 mL in 1 litre: g/L = (g/100 mL) × (1000 mL/L) = (% w/v/100) × 1000 = % w/v × 10. For example, 5% w/v = 50 g/L; 0.9% w/v NaCl = 9 g/L. Knowing this conversion is essential for clinical drug preparation and environmental standards expressed in mg/L.
The calculator computes % w/v for a single solute. For multi-component solutions (e.g., PBS containing NaCl, KCl, Na₂HPO₄, and KH₂PO₄), calculate the % w/v for each component individually by entering the mass of that component and the total solution volume. The total % w/v of the solution (if needed) is the sum of all individual % w/v values. For molarity of each component, use the Concentration Calculator with the individual masses.
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