What is Specific Gravity?
Specific gravity (SG) is a unitless value that compares the density of a substance to the density of water at 4°C (1000 kg/m³). If a substance has an SG greater than 1, it sinks in water; if it is less than 1, it floats.
What is Density?
Density is the mass per unit volume of a substance, measured in kg/m³ (SI unit). It indicates how much matter is packed into a given space.
Formula for Converting Specific Gravity and Density
- Density (kg/m³) = Specific Gravity × 1000
- Specific Gravity = Density (kg/m³) / 1000
Step-by-Step Calculation
- Find the given value: Either specific gravity or density.
- Use the appropriate formula: Multiply by 1000 to get density, or divide by 1000 to get SG.
- Interpret the result: Compare with water’s density to determine if the substance floats or sinks.
Common Substances: Specific Gravity & Density
| Substance | Specific Gravity | Density (kg/m³) |
|---|---|---|
| Water (4°C) | 1.00 | 1000 |
| Ice | 0.92 | 920 |
| Ethanol | 0.79 | 790 |
| Aluminum | 2.70 | 2700 |
| Iron | 7.87 | 7870 |
| Gold | 19.32 | 19320 |
| Mercury | 13.55 | 13550 |
| Air (20°C) | 0.0012 | 1.2 |
Asked by Students
Q: Can specific gravity be negative?
A: No, specific gravity is always positive since it is a ratio of densities.
Q: Does temperature affect specific gravity?
A: Yes, as temperature changes, the density of substances changes, affecting specific gravity.
Q: Why is water’s specific gravity 1?
A: Because it is the reference substance used for comparison.
Use this calculator to convert between specific gravity and density for various substances quickly!
