IES
Chemical Engineering2D

Fluid Density Calculator

Calculate fluid density from SG (specific gravity) or API gravity, with temperature correction for water.

Inputs
Enter your values below

Water=1, Oil≈0.85-0.95, Gasoline≈0.75

Result
Fluid Density
—
Enter values and click Calculate
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Formula
sg × 1000
Result unit: kg/m³

ρ = SG × ρ_water = SG × 1000 kg/m³. Specific gravity is the ratio of fluid density to water at 4°C.

Introduction

Convert specific gravity to density in kg/m³. Essential for hydraulic calculations, pump sizing, and mass flow conversions. Includes common fluid SG values.

How This Calculator Works

ρ = SG × ρ_water = SG × 1000 kg/m³. Specific gravity is the ratio of fluid density to water at 4°C.

Step-by-step process:

  1. Enter your input values in the calculator above
  2. The engine converts all inputs to SI base units (meters, kg, Pa)
  3. The formula is evaluated: sg * 1000
  4. Result is formatted with the appropriate unit and precision

Calculation Example

Crude oil with SG=0.85 has density 850 kg/m³.

Inputs: sg=0.85
Result: 850 kg/m³

Engineering Applications

  • •Hydraulic calculations
  • •Mass flow conversion
  • •Pump sizing
  • •Process engineering

Frequently Asked Questions

What is API gravity?

API = (141.5/SG) − 131.5. Water has API 10°. Light oils have high API; heavy oils have low API. SG=0.85 → API=35°.

How does temperature affect density?

Most fluids expand when heated, reducing density. Water: ~1000 kg/m³ at 4°C, ~998 at 20°C, ~958 at 100°C. Use operating temperature densities for accurate pump calcs.

How do I convert density between kg/m³ and lb/ft³?

1 kg/m³ = 0.06243 lb/ft³. For example, 800 kg/m³ = 49.94 lb/ft³. Conversely, multiply lb/ft³ by 16.018 to get kg/m³.

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Engineering Disclaimer: Calculations are for reference and educational purposes only. Always verify results independently for engineering design. See full disclaimer.
Reviewed by: Industrial Engineering Team
References: ASME B31.3, ASTM A36, Perry's Chemical Engineers' Handbook