🧪 Multi-Unit Density Engine

Density & Specific Gravity Converter

Q: What is the difference between Density and Specific Gravity (SG)?

Density is the physical mass of a substance per unit of volume (expressed in units like kg/L, g/cm³, or lb/gal). Specific Gravity (SG) (also known as relative density) is a dimensionless ratio comparing the density of a substance to the density of pure reference water at 4°C (1.0000 kg/L or 1.0000 g/cm³). Because pure water has a density of 1.000 kg/L, a substance with a specific gravity of 0.832 has a metric density of exactly 0.832 kg/L.

Q: How do you convert g/cm³ to kg/m³?

Multiply grams per cubic centimeter (g/cm³) by 1,000 to get kilograms per cubic meter (kg/m³). 1 g/cm³ = 1,000 kg/m³ = 1 kg/L = 1 g/mL.

Convert instantly across metric mass density, imperial volume weights, specific gravity (SG), and petroleum API gravity.

Quick Presets:

Reference Standard Pure Water @ 4°C = 1.0000 kg/L = 1.0000 g/cm³ = 8.3454 lb/gal

Browse 50+ Material Densities

Enter Density Value

Source Unit

All Equivalent Density Formats Live Computed

kg / Liter (kg/L)

1.0000

Metric Standard

g / cm³ (g/mL)

1.0000

Laboratory CGS

kg / m³

1000.00

SI Base Unit

lb / US Gallon

8.3454

US Liquid Weight

Specific Gravity (SG)

1.0000

Ratio to Water

lb / ft³

62.428

Imperial Bulk

lb / UK Imperial Gal

10.022

UK Commonwealth

°API Gravity

10.00°

Petroleum Standard

Hydrometer Float & Buoyancy Visualizer Neutral Buoyancy (Floats on Water Level)

A hydrometer measures the specific gravity of liquids based on the Archimedes buoyancy principle. In lighter liquids (like gasoline at SG 0.745), the hydrometer sinks deeper. In heavy liquids (like honey at SG 1.420), it floats higher.

Relative Density Ratio: Specific Gravity = 1.0000 (100% of pure water density)

Hydrometer Stem

Interactive Archimedes Solid Float & Immersion Simulator

According to Archimedes' principle, any object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced. If the object's solid density is less than the fluid density, it floats with a fraction of its volume submerged: Submerged % = (Solid Density ÷ Fluid Density) × 100%.

Buoyancy State

Floats on Surface

50.0% Submerged Volume

Active Fluid Density

1.0000 kg/L

Pure Water Reference

Apparent Net Force

Positive Buoyant (+0.50 kg/L)

Archimedes Force Balance

🛢️ Petroleum Engineering & Heavy Liquids (API / Baumé)

Petroleum API Gravity (°API) & Baumé Scale (°Bé) Converter

The American Petroleum Institute (API) Gravity scale measures how heavy or light a petroleum liquid is compared to water: °API = (141.5 ÷ SG @ 60°F) − 131.5. Water has an API gravity of exactly 10.0° API.

Specific Gravity (SG @ 60°F):

Petroleum Crude Presets:

Petroleum Classification:

Light Sweet Crude Floats on Water (>10° API)

API Gravity (°API)

34.97° API

Higher = Lighter & more valuable

Baumé Scale (°Bé)

0.00° Bé

145 − (145 ÷ SG)

Density in Pounds / Gallon

7.094 lb/gal

849.5 kg/m³

Weight per Barrel (42 Gal)

297.9 lbs / bbl

135.1 kg / barrel

💨 Gas Physics & Ideal Gas Law (PV = nRT)

Ideal Gas Density at Custom Temperature & Pressure Calculator

Gases compress and expand dramatically with temperature and pressure according to the ideal gas equation of state: ρ = (P × M) ÷ (R × T).

Gas Specie & Molar Mass:

Gas Temperature: 20°C (68°F)

Pressure (Atmospheres): 1.00 atm (101.3 kPa)

Gas Density (kg/m³)

1.204 kg/m³

SI Volumetric Density

Density in Grams / Liter

1.204 g/L

1 kg/m³ = 1 g/L

Imperial Density (lb/cu ft)

0.0752 lb/ft³

Air standard @ STP ~0.08 lb/ft³

Relative Density to Air

1.000 (Air Basis)

Specific gravity in air

Exact Density Conversion Multipliers

Multiply any value in kg/L (or Specific Gravity) by the factors below to convert directly into standard imperial or metric units.

Target Unit	Formula from kg/L	Multiplier	Water Equivalent
Pounds per US Gallon (lb/gal)	kg/L × 8.345404	8.345404	8.3454 lb/gal
Grams per Milliliter (g/cm³)	kg/L × 1.000000	1.000000	1.0000 g/cm³
Kilograms per Cubic Meter (kg/m³)	kg/L × 1,000.00	1000.0	1,000.00 kg/m³
Pounds per Cubic Foot (lb/ft³)	kg/L × 62.42796	62.42796	62.428 lb/ft³
Pounds per UK Imperial Gallon	kg/L × 10.02241	10.02241	10.022 lb/gal

Authoritative Reference Database

Substance Density Reference Library

Search densities verified against NIST, ASTM, IATA, and USDA standard reference values.

Substance	Category	Density (kg/L)	Ref. Temperature	Standard Source	Action

Showing 45 substances Verified against ASTM, NIST, IATA, USDA standards

Answers & Clarity

Frequently Asked Questions

Direct answers to the most common mass-to-volume conversion queries.

What is the difference between Density and Specific Gravity (SG)?

Density is the physical mass of a substance per unit of volume (expressed in units like kg/L, g/cm³, or lb/gal). Specific Gravity (SG) (also known as relative density) is a dimensionless ratio comparing the density of a substance to the density of pure reference water at 4°C (1.0000 kg/L or 1.0000 g/cm³). Because pure water has a density of 1.000 kg/L, a substance with a specific gravity of 0.832 has a metric density of exactly 0.832 kg/L.

How do you convert kg/L to lb/US gallon?

To convert kilograms per liter (kg/L) to pounds per US liquid gallon (lb/gal), multiply by 8.345404:
lb/gal = kg/L × 8.345404
For example, water at 1.000 kg/L = 8.3454 lb/gal. Diesel fuel at 0.832 kg/L = 0.832 × 8.3454 = 6.943 lb/gal.

How do you convert g/cm³ to kg/m³?

How is API Gravity calculated from Specific Gravity in petroleum engineering?

API Gravity (American Petroleum Institute gravity) measures how heavy or light a petroleum liquid is compared to water:
°API = (141.5 ÷ Specific Gravity) - 131.5
Petroleum with an API gravity greater than 10° is lighter than water and will float. Light crude oil has an API gravity above 31.1°.