Calculate liquid density from mass and volume, or solve for mass, volume, or specific gravity, using measured density or 22 liquid lookup choices. Fresh-water lookup supports 5–40°C; other lookup values are nominal estimates at 20°C.
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Liquid Density Formula
The calculator uses the standard density relationship and rearranges it for the value you need.
- density: mass per unit volume of the liquid (g/mL, kg/m³, lb/gal, etc.)
- mass: mass of the liquid sample (g, kg, lb, oz); weight is a force and is not entered here
- volume: space the liquid occupies (mL, L, m³, US gal, fl oz, ft³)
Find density: enter mass and volume. The calculator converts mass to kilograms and volume to cubic meters, then divides. Tare mode subtracts the empty container mass before dividing.
Find mass: pick a liquid (or enter a custom density) and a volume. The calculator multiplies density by volume.
Find volume: pick a liquid (or enter a custom density) and a mass. The calculator divides mass by density.
Reference Tables
These rounded values match the nominal 20°C lookup estimates. They are rough starting points, not validated specifications for every product or mixture. Real density depends on temperature, pressure and composition. Use measured or manufacturer density when accuracy matters.
| Liquid | g/mL | kg/m³ | lb/US gal |
|---|---|---|---|
| Gasoline | 0.745 | 745 | 6.22 |
| Acetone | 0.7908 | 790.8 | 6.60 |
| Isopropyl alcohol | 0.7855 | 785.5 | 6.56 |
| Ethanol | 0.789 | 789 | 6.58 |
| Olive oil | 0.915 | 915 | 7.64 |
| Vegetable oil | 0.92 | 920 | 7.68 |
| Water (20°C) | 0.998201 | 998.200771 | 8.33 |
| Seawater | 1.0248 | 1024.8 | 8.55 |
| Milk | 1.03 | 1030 | 8.60 |
| Glycerin | 1.261 | 1261 | 10.52 |
| Honey | 1.42 | 1420 | 11.85 |
| Mercury | 13.534 | 13534 | 112.95 |
Common density unit conversions:
| From | To | Multiply by |
|---|---|---|
| g/mL | kg/m³ | 1000 |
| g/mL | lb/US gal | 8.3454 |
| g/mL | lb/ft³ | 62.428 |
| kg/m³ | lb/ft³ | 0.06243 |
| lb/US gal | g/mL | 0.11983 |
Examples and FAQ
Example 1. A graduated cylinder holds 250 mL of an unknown liquid weighing 197.25 g. Density = 197.25 / 250 = 0.789 g/mL. This is close to the nominal ethanol lookup density, but density alone does not identify the liquid.
Example 2. Using the nominal gasoline lookup density of 745 kg/m³ at 20°C, what is the mass of 5 US gallons? Volume = 5 × 0.003785411784 = 0.01892705892 m³. Mass = 745 × 0.01892705892 = 14.1006588954 kg, or about 31.09 lb. Actual gasoline blend density varies.
Does temperature change density? Yes. Most liquids expand as they warm, so density drops. Water is about 1.000 g/mL at 4°C and 0.998 g/mL at 20°C. The fresh-water lookup uses the NIST Jones–Harris air-saturated-water approximation from 5–40°C at 101.325 kPa. Nonwater lookups are nominal 20°C values, with no automatic temperature correction. Enter a sample-specific density for other conditions. The separately tabulated 4°C water reference is approximately 999.972 kg/m³ (NIST reference tables).
What is specific gravity? It is the density of a liquid divided by the density of water. The sample and reference-water temperatures must be stated. A specific gravity of 1.26 means 1.26 times the selected reference-water density; it does not establish whether liquids will form separate layers. Glycerin and water mix. For qualified petroleum samples only, API gravity = 141.5 / SG(60°F/60°F) − 131.5; the calculator requires both reference and sample temperatures to be 60°F.
Why does my measured density differ from a reference value? Common reasons are temperature, dissolved solids or gases, contamination, and measurement error in the scale or volume. Calibrate the equipment and check the temperature before assuming the liquid is off-spec.
Can I use this for gases or solids? The formula is the same, but the unit ranges and density values built into this tool are tuned for liquids. For gases you also need pressure and temperature to get a meaningful number.
