Specific Gravity Calculator

What Is a Specific Gravity Calculator?

Specific gravity compares the density of a substance to the density of a reference material, almost always water for liquids and solids, or air for gases. Because it's a ratio of two densities, specific gravity is a pure number with no units.

This calculator first computes your sample's density from mass and volume, then divides it by your chosen reference density to give the specific gravity.

How to Read Your Results

Specific Gravity

This unitless number tells you how many times denser your sample is than the reference substance. A value of 2.0 means your sample is twice as dense as the reference.

Sample Density

Your sample's mass divided by its volume, in grams per cubic centimeter — the raw density value used to compute specific gravity.

Reference Density Used

The density of whichever reference substance you selected (water, air, or a custom value), shown so you can verify the comparison being made.

Floats or Sinks (in Water)

When water is the reference, a specific gravity below 1.0 means the substance floats; above 1.0 means it sinks; exactly 1.0 means neutral buoyancy.

Real-World Example

A sample weighs 150 g and displaces 200 cm³ of water:

With a specific gravity of 0.750 — less than 1.0 — this sample would float in water, similar to many oils and some plastics.

Tips for Accurate Specific Gravity

• Measure temperature carefully. Both the sample and the reference substance's density can shift with temperature.
• Use a graduated cylinder or displacement method for irregular solids to get an accurate volume.
• Remember specific gravity is unitless — it's identical whether you measure mass in grams or pounds, as long as both mass and volume use consistent units.
• For gases, always compare to air at the same temperature and pressure, not to water.

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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team