Density is mass per unit volume. Pick a substance or enter a density to convert between volume and weight.
What is the Volume ↔ Weight Converter?
This tool converts between volume and weight (mass) using the density of a substance. A plain unit converter cannot turn liters into kilograms, because one liter of water, honey and mercury all weigh very different amounts. What makes the difference is density.
The converter includes 30 common substances — water, seawater, milk, concrete, sand, steel, flour and more. Just pick a substance, enter a volume (or weight), and it applies the density automatically. If your material isn't listed, you can enter its density directly. It's handy for scaling recipes, estimating construction and DIY materials, and learning science.
How to use it
1. Choose a direction (volume → weight, or weight → volume).
2. Pick a substance (or choose “Custom density” and type a density).
3. Enter a value and unit (e.g. 1 liter).
4. Choose the output unit (e.g. kilograms).
5. Read the converted result, plus the kg/g (or L/m³) readouts below.
Formula and definitions
mass = volume × density
volume = mass ÷ density
Density is mass per unit volume, expressed in kg/m³. Example: water has a density of about 1000 kg/m³, so 1 liter (0.001 m³) of water weighs about 1 kg. Concrete (about 2400 kg/m³) means 1 liter weighs about 2.4 kg.
How to read the result
The large number is the converted value in your chosen unit. Below it you'll see the value in kg/g (or L/m³ when converting to volume). Cooking ingredients and bulk solids like sand or cement don't have a fixed density — it changes with packing and moisture — so those values are estimates. Weigh the material directly when accuracy matters.
Frequently asked questions
Why do I need density to convert volume to weight? ▾
Because volume and weight (mass) are different quantities. Density (mass per unit volume) is what links them. One liter of water weighs about 1 kg, but one liter of honey is about 1.4 kg and one liter of mercury about 13.5 kg.
How many kilograms is one cubic meter of water? ▾
About 1000 kg (one tonne). Water's density is about 1000 kg/m³, so 1 m³ = 1000 liters ≈ 1000 kg (it varies slightly with temperature).
How much do concrete and sand weigh? ▾
Concrete is about 2400 kg/m³, so 1 m³ weighs about 2.4 tonnes. Dry sand is about 1600 kg/m³, so 1 m³ is about 1.6 tonnes. Wet sand and gravel weigh more.
How many grams is one cup of flour? ▾
Flour's density is about 530 kg/m³, so a US cup (~237 mL) holds about 125 g and a metric cup (250 mL) about 133 g. It's an estimate, since sifting and packing change the result.
Does temperature affect the result? ▾
Yes — especially for liquids, whose density changes with temperature. Water is densest near 4 °C and gets lighter as it warms. This tool uses about 20 °C, so very different temperatures introduce some error.
Density varies with temperature, pressure, grade, moisture and packing. The values shown are estimates based on representative densities. Use measured values when accuracy is required.