What is specific gravity?

Specific gravity is the ratio of the density of a substance to the density of a reference substance — almost always pure water at 4 °C (1.000 g/mL). It is dimensionless. A solution with SG = 1.20 is 20 % denser than pure water.

What reference temperature should I use?

Most chemistry tables use 4 °C (water density = 1.000 g/mL). Practical lab work often uses 20 °C (water density = 0.9982 g/mL). Select whichever matches your hydrometer calibration or reference source.

How is mass concentration estimated from SG?

Many simple solutions follow an approximately linear SG–concentration relationship near room temperature. If you know the empirical slope (Δg per L per SG unit) for your solute, the calculator applies: concentration = (SG − 1) × slope. This is an approximation; consult published tables for high-accuracy work.

What units can I enter density in?

g/mL and g/cm³ are numerically identical (1 g/mL = 1 g/cm³). kg/m³ is divided by 1000 internally. The result is always the dimensionless SG ratio.

Is specific gravity the same as relative density?

Yes — "relative density" and "specific gravity" are synonymous when water is the reference. The term "specific gravity" is older and still common in industry; "relative density" is the IUPAC-preferred term.

Specific Gravity Solution Calculator

Enter a solution density to instantly calculate its specific gravity, or convert between density, specific gravity, and mass concentration.

Solution Density Input

Solution Density

Water Reference Temperature

Optional: Estimate Mass Concentration

Provide the empirical slope (g/L per SG unit) for your solute to estimate approximate mass concentration. Example: for NaCl ≈ 360 g/L per SG unit.

Concentration Slope (g/L per SG unit)

Results

Specific Gravity (SG)

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Density (g/mL)

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Density (kg/m³)

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Relative Density vs Water

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Common Solution Reference

Solution	SG	g/mL
Pure water (4 °C)	1.000	1.000
Seawater (typical)	1.025	1.025
10% NaCl solution	1.071	1.071
Conc. H₂SO₄ (98%)	1.840	1.840
Conc. HCl (37%)	1.190	1.190
Ethanol (pure)	0.789	0.789

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Summary

Specific gravity (SG) is the ratio of a solution's density to the density of pure water at 4 °C (1.000 g/mL). This calculator lets you enter any solution density in g/mL, g/cm³, or kg/m³ and instantly computes SG, relative density, and optional mass concentration using a linear approximation. Results update in real time with no server round-trip.

How it works

Enter the solution density in your preferred unit (g/mL, g/cm³, or kg/m³).
Select the reference temperature if needed (4 °C water = 1.000 g/mL; 20 °C water = 0.9982 g/mL).
The calculator divides solution density by reference water density to produce specific gravity.
Optionally enter an empirical SG–concentration slope to estimate mass concentration (w/v, g/L).
Copy any result with one click.

Use cases

Verify the specific gravity of a prepared reagent against a reference value.
Convert hydrometer readings to g/mL density.
Estimate acid or base concentration from measured SG.
Quality-control checks on saline, sugar, or alcohol solutions.
Teaching specific gravity concepts in a chemistry lab setting.
Convert between SI density (kg/m³) and dimensionless SG for engineering calculations.

Frequently Asked Questions

Last updated: 2026-06-04 · Reviewed by Nham Vu