Calculator Form
Formula Used
SG = ρsample / ρwater
ρsample = m / V
SG = ρsample / ρwater
SG = Wair / (Wair − Wwater)
ρ(T) = 999.842594 + 0.06793952T − 0.00909529T² + 0.0001001685T³ − 0.000001120083T⁴ + 0.000000006536332T⁵
Specific gravity is dimensionless. It compares a sample density to a chosen water reference density. Values above 1 are denser than water. Values below 1 are less dense than water.
How to Use This Calculator
- Select a calculation method that matches your available measurements.
- Enter the reference temperature or choose a fixed 4°C reference.
- Use custom water density only when your lab standard requires it.
- Fill in the density, mass-volume, or hydrostatic inputs.
- Press the calculate button to display the result above the form.
- Review the interpretation, chart, and converted density values.
- Download CSV for tabular records or PDF for sharing.
Example Data Table
| Case | Method | Input Summary | Reference Water Density | Specific Gravity | Interpretation |
|---|---|---|---|---|---|
| Pure water baseline | Known density | 1000 kg/m³ | 999.975 kg/m³ at 4°C | 1.0000 | Essentially equal to water |
| Seawater sample | Known density | 1025 kg/m³ | 998.206 kg/m³ at 20°C | 1.0268 | Denser than water |
| Ethanol sample | Known density | 789 kg/m³ | 998.206 kg/m³ at 20°C | 0.7904 | Less dense than water |
| Lab specimen | Mass and volume | 2.5 kg / 0.0024 m³ | 998.206 kg/m³ at 20°C | 1.0435 | Slightly denser than water |
| Quartz-like solid | Hydrostatic | 98 N in air / 61 N in water | 998.206 kg/m³ at 20°C | 2.6486 | Much denser than water |
Frequently Asked Questions
1) What is water specific gravity?
It is the ratio between a sample’s density and a chosen water density reference. The result has no unit. It tells you whether a material is lighter or heavier than water.
2) Why does temperature matter?
Water density changes with temperature. Using the correct reference improves accuracy, especially in laboratory work, fluid comparison, and quality control calculations.
3) Is specific gravity the same as density?
No. Density has units such as kg/m³. Specific gravity is dimensionless because it compares one density to another reference density.
4) Can this calculator be used for solids?
Yes. Use the hydrostatic weighing method for solids when you know the weight in air and the apparent weight while submerged in water.
5) What does a value below 1 mean?
A value below 1 means the sample is less dense than water. In many practical situations, that indicates the sample would float on water.
6) Which reference should I choose?
Choose water at the measured temperature for realistic field conditions. Choose 4°C for standard reference work. Use custom density only when your procedure specifies it.
7) Can I use pounds, feet, liters, and grams?
Yes. The form converts common density, mass, volume, and force units automatically before calculating the final specific gravity and sample density.
8) How accurate is hydrostatic weighing?
It is reliable when air bubbles are removed, the sample is fully submerged, and readings are stable. Small measurement errors can noticeably affect the final ratio.