Specific Gravity Calculator
Compute specific gravity (SG) from density, convert SG back to density in any unit, determine SG by hydrostatic weighing (Archimedes), interpret urine SG readings, and look up a reference table of 26 materials. Every result also shows the °API and °Baumé equivalents.
Gold is 19.32, ethanol 0.789, mercury 13.546. Tap a material in the table below to load it.
SG = weight in air / (weight in air − weight in water). Works for non-porous solids that sink; both weighings must use the same unit.
Typical dipstick/refractometer reading, e.g. 1.025. Normal adult range: 1.005–1.030.
Try a material
Tap one to load its density into the Density → SG tab.
Specific gravity reference table
| Material | SG | Density (kg/m³) | Note |
|---|---|---|---|
| Platinum | 21.45 | 21449.4 | |
| Gold | 19.32 | 19319.5 | |
| Mercury | 13.546 | 13545.6 | |
| Lead | 11.34 | 11339.7 | |
| Silver | 10.49 | 10489.7 | |
| Copper | 8.96 | 8959.7 | |
| Nickel | 8.91 | 8909.8 | |
| Brass | 8.50 | 8499.8 | approx. |
| Iron | 7.87 | 7869.8 | |
| Carbon steel | 7.85 | 7849.8 | |
| Tin | 7.31 | 7309.8 | |
| Zinc | 7.14 | 7139.8 | |
| Titanium | 4.51 | 4509.9 | |
| Diamond | 3.52 | 3519.9 | |
| Aluminum | 2.70 | 2699.9 | |
| Quartz | 2.65 | 2649.9 | |
| Soda-lime glass | 2.50 | 2499.9 | approx. |
| Concrete | 2.40 | 2399.9 | approx. |
| Sulfuric acid (concentrated) | 1.84 | 1839.9 | approx. |
| Glycerin | 1.26 | 1260.0 | |
| Seawater | 1.025 | 1025.0 | approx. |
| Ice (0°C) | 0.917 | 917.0 | |
| Olive oil | 0.91 | 910.0 | approx. |
| Diesel fuel | 0.85 | 850.0 | approx. |
| Ethanol | 0.789 | 789.0 | |
| Gasoline | 0.74 | 740.0 | approx. |
SG values are relative to water at 4°C; density = SG × 999.972 kg/m³. Rows marked "approx." depend on alloy, grade, or temperature — treat them as typical values, not exact constants.
Honest notes (read before trusting the numbers)
Which nrtechstudio tool do you need?
Specific Gravity Calculator (this page): specific gravity as the main subject — SG from density, density from SG, hydrostatic weighing, urine SG, material table.
For petroleum API gravity conversions (the °API scale, crude classification, blending), see our API Gravity Calculator.
For plain density unit conversion (kg/m³ ↔ lb/ft³ ↔ g/cm³ …), use our Density Unit Converter.
For solving density from mass and volume of an object (3-way solver with shapes and a material table), use our Volume to Density Calculator.
For buoyant force in newtons (Archimedes force, apparent weight, fraction submerged), use our Buoyant Force Calculator.
Frequently asked questions
What is specific gravity?
Specific gravity (SG) is the ratio of a substance's density to the density of water at a stated temperature. It is dimensionless — it has no units — because the units cancel: SG = ρ_substance / ρ_water. Pure water at the reference temperature has SG = 1.000 exactly.
How do I calculate specific gravity from density?
Divide the density by the density of water at your reference temperature. Example: ethanol at 789 kg/m³, referenced to water at 4°C (999.972 kg/m³) → 789 / 999.972 = 0.7890. The Density → SG tab on this page does this for 9 density units and 3 water references.
How do I convert specific gravity back to density?
Multiply SG by the water reference density. Example: gold at SG 19.32 → 19.32 × 999.972 kg/m³ = 19319.5 kg/m³. The SG → Density tab converts into 9 units including g/cm³, lb/ft³ and lb/US gal.
How does the hydrostatic weighing (Archimedes) method work?
Weigh the object in air, then weigh it fully submerged in water. SG = weight in air / (weight in air − weight in water). Example: 100 g in air, 87 g in water → 100 / (100 − 87) = 100 / 13 = 7.6923. The lost weight equals the weight of the displaced water, so the ratio gives the object's density relative to water. Both weighings must use the same unit, and the object must sink without absorbing water.
Which water reference temperature should I use?
Use the reference your field expects: 4°C (999.972 kg/m³, the maximum density of water, the SI reference), 20°C (998.2071 kg/m³, common in laboratories), or 60°F (999.016 kg/m³, the ASTM D1250 petroleum reference used with °API). The popular shortcut “water = 1000 kg/m³” is off by about 0.03% — fine for estimates, not for metrology.
What is the normal urine specific gravity range?
The typical clinical reference range for a healthy adult is 1.005 to 1.030. Below 1.005 is considered dilute (often from high fluid intake); above 1.030 is concentrated (commonly a sign of dehydration). This is an educational interpretation only — it is not medical advice and cannot diagnose anything. See a clinician about any abnormal or persistent reading.
What is the difference between specific gravity and density?
Density is mass per unit volume (for example kg/m³) and depends on the unit system. Specific gravity is the ratio of that density to water's density, so it is a pure number with no units — SG 0.789 means “0.789 times as dense as water” in every unit system. To go between them you only need the water reference density.
Can specific gravity be less than 1?
Yes. Anything less dense than water has SG below 1 and floats: ethanol is 0.789, gasoline about 0.74, ice 0.917. Anything denser than water is above 1: aluminum 2.70, iron 7.87, gold 19.32, mercury 13.546.
How do I convert specific gravity to degrees API?
Use °API = 141.5 / SG − 131.5 (defined for petroleum at 60°F/60°F). Example: SG 0.85 → 141.5 / 0.85 = 166.47, minus 131.5 = 34.97° API. For full petroleum work — crude classification, benchmarks, blending — see our API Gravity Calculator.
What is the Baumé scale and how does it relate to SG?
Baumé (°Bé) is a legacy hydrometer scale still used in some industries. For liquids heavier than water: °Bé = 145 − 145/SG (example: SG 1.2 → 145 − 120.83 = 24.17°Bé). For liquids lighter than water: °Bé = 140/SG − 130 (example: SG 0.9 → 155.56 − 130 = 25.56°Bé).
Why do gold buyers test specific gravity?
Because gold's SG of 19.32 is far higher than most fakes and base metals, a weighing test is a quick authenticity check: real gold at 19.32 × 999.972 kg/m³ weighs 19319.5 kg per cubic metre. Tungsten (19.25) is the notable exception that defeats this test, so dealers combine SG with other checks.
Which nrtechstudio tool should I use for my task?
Use this Specific Gravity Calculator when specific gravity itself is the subject: SG from density, density from SG, hydrostatic weighing, urine SG, or the material table. Use our API Gravity Calculator for the petroleum °API scale (crude classification and blending). Use our Density Unit Converter for plain unit changes such as kg/m³ to lb/ft³. Use our Volume to Density Calculator when you know an object's mass and volume. Use our Buoyant Force Calculator when you need the Archimedes force in newtons.