Specific Gravity Calculator
Calculate specific gravity from density
Density of the material (if in kg/m³, divide by 1000)
How to Use This Calculator
Enter Material Density
Input the density of your material in g/cm³. If you have density in kg/m³, divide by 1000 first (e.g., 7850 kg/m³ becomes 7.85 g/cm³). This is the density of the material you want to analyze.
Select Reference Material
Choose the reference material. Typically, water at 4°C (density = 1.0 g/cm³) is used. You can also select a custom reference density if needed for specific applications.
Calculate Specific Gravity
Click "Calculate" to determine the specific gravity. The result is dimensionless and represents how many times denser (or lighter) the material is compared to the reference.
Formula
Specific Gravity = Material Density ÷ Reference Density
SG = ρ_material / ρ_reference
Where:
- SG = Specific gravity (dimensionless)
- ρ_material = Density of the material - g/cm³
- ρ_reference = Density of reference (typically water = 1.0 g/cm³ at 4°C)
Note:
Specific gravity is dimensionless because it's a ratio of densities. When water at 4°C (1.0 g/cm³) is the reference, specific gravity numerically equals density in g/cm³.
Example:
For steel with density 7.85 g/cm³:
SG = 7.85 ÷ 1.0 = 7.85
About Specific Gravity Calculator
The Specific Gravity Calculator is an essential tool for materials science, chemistry, and engineering that calculates specific gravity (also called relative density) from material density. Specific gravity is a dimensionless quantity that compares a material's density to that of a reference substance, typically water at 4°C. It is widely used for material identification, quality control, and material selection.
When to Use This Calculator
- Material Identification: Identify unknown materials by comparing specific gravity
- Quality Control: Verify materials meet density specifications
- Material Selection: Compare materials based on density relative to water
- Chemical Analysis: Determine concentration and purity of solutions
- Geological Applications: Characterize minerals and rocks
Why Use Our Calculator?
- ✅ Quick Calculation: Instant specific gravity from density
- ✅ Material Property: Essential dimensionless property for material comparison
- ✅ Flexible Reference: Use water or custom reference density
- ✅ Educational Resource: Understand specific gravity concepts
- ✅ Accurate Results: Precise calculations for scientific applications
Key Concepts
Specific Gravity (SG): A dimensionless quantity that expresses the ratio of a material's density to the density of a reference substance (typically water at 4°C). It indicates how many times denser or lighter a material is compared to water. Since it's a ratio, specific gravity has no units.
Reference Material: Water at 4°C (where water has its maximum density of 1.0 g/cm³) is the standard reference. For gases, air is sometimes used as a reference. When water is the reference and density is in g/cm³, specific gravity numerically equals density.
Typical Values
- Metals: 2.5-20 (e.g., Aluminum: 2.7, Steel: 7.85, Lead: 11.3, Gold: 19.3)
- Wood: 0.3-1.2 (depends on species and moisture)
- Plastics: 0.9-2.2 (e.g., Polyethylene: 0.92, PVC: 1.4)
- Concrete: 2.2-2.5
- Ice: 0.917 (less than water, so it floats)
Frequently Asked Questions
What is specific gravity?
Specific gravity (SG) is a dimensionless quantity that compares a material's density to the density of a reference substance, typically water at 4°C. It is calculated as SG = ρ_material / ρ_reference. Since it's a ratio of densities, it has no units.
Why is water at 4°C used as the reference?
Water reaches its maximum density at 4°C (1.0 g/cm³), making it a stable and convenient reference point. At this temperature, water's density is exactly 1.0 g/cm³, so specific gravity numerically equals density when expressed in g/cm³. This simplifies calculations and provides a consistent standard.
What's the difference between density and specific gravity?
Density has units (g/cm³, kg/m³, etc.) and represents mass per unit volume. Specific gravity is dimensionless and is the ratio of a material's density to a reference density (typically water). When using water at 4°C as reference and density in g/cm³, specific gravity numerically equals density, but conceptually they are different - density is absolute, specific gravity is relative.
Can specific gravity be less than 1?
Yes! Materials with specific gravity less than 1 are lighter than water and will float. Examples include most woods (SG ≈ 0.3-0.9), many plastics (SG ≈ 0.9-1.0), and ice (SG ≈ 0.917). Materials with SG > 1 are denser than water and will sink.
How is specific gravity used in material identification?
Specific gravity is used as a material property for identification because it's independent of sample size. By measuring the density (and thus specific gravity) of an unknown material and comparing it to known values, you can identify the material. This is commonly used in geology for mineral identification, in metallurgy for alloy identification, and in quality control to verify material composition.