Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

Density vs. Specific Weight and Specific Gravity

Sponsored Links

Density is defined as mass per unit volume . Mass is a property and the SI unit for density is [kg/m3].

Density can be expressed as

ρ = m / V   = 1 / ν                    (1)

where
ρ = density [kg/m3], [slugs/ft3]
m = mass [kg], [slugs]
V = volume [m3], [ft3]
ν = specific volume [m3 /kg], [ft3 /slug]

The Imperial (U.S.) units for density are slugs /ft3 but pound-mass per cubic foot - lbm /ft3 - is often used. Note that there is a difference between pound-force (lbf) and pound-mass (lbm) . Slugs can be multiplied with 32.2 for a rough value in pound-mass (lbm) .

  • 1 slug = 32.174 lbm = 14.594 kg
  • 1 kg = 2.2046 lbm = 6.8521x10-2 slugs
  • density of water: 1000 kg/m3 , 1.938 slugs/ft3

See also Unit converter - mass and Unit converter - density

On atomic level - particles are packed tighter inside a substance with higher density. Density is a physical property - constant at a given temperature and pressure - and may be helpful for identification of substances.

Below on this page: Specific gravity (relative density) , Specific gravity for gases , Specific weight , Calculation examples

Se also:

Specific Gravity (Relative Density) - SG - is a dimensionless unit defined as the ratio of the density of a substance to the density of water - at a specified temperature and can be expressed as

SG = ρsubstance / ρH2O                 (2)

where
SG = Specific Gravity of the substance
ρsubstance = density of the fluid or substance [kg/m3]
ρH2O = density of water - normally at temperature 4 oC [kg/m3]

It is common to use the density of water at 4 oC (39 oF) as a reference since water at this point has its highest density of 1000 kg/m 3 or 1.940 slugs/ft3 .

Since Specific Gravity - SG -  is dimensionless, it has the same value in the SI system and the imperial English system (BG). SG of a fluid has the same numerical value as its density expressed in g/mL or Mg/m3 . Water is normally also used as reference when calculating the specific gravity for solids.

See also Thermophysical Properties of Water - Density, Freezing temperature, Boiling temperature, Latent heat of melting, Latent heat of evaporation, Critical temperature ...

Specific Gravity for some common Materials

Specific Gravities common Substances
SubstanceSpecific Gravity
- SG -
Acetylene 0.0017
Air, dry 0.0013
Alcohol 0.82
Aluminum 2.72
Brass 8.48
Cadmium 8.57
Chromium 7.03
Copper 8.79
Carbon dioxide 0.00198
Carbon monoxide 0.00126
Cast iron 7.20
Hydrogen 0.00009
Lead 11.35
Mercury 13.59
Nickel 8.73
Nitrogen 0.00125
Nylon 1.12
Oxygen 0.00143
Paraffin 0.80
Petrol 0.72
PVC 1.36
Rubber 0.96
Steel 7.82
Tin 7.28
Zinc 7.12
Water (4 oC) 1.00
Water, sea 1.027
Wood, Oak 0.77

Specific Gravity of gases is normally calculated with reference to air - and defined as the ratio of the density of the gas to the density of the air - at a specified temperature and pressure.

The Specific Gravity can be calculated as

SG = ρgas / ρair                 (3)

where
SG = specific gravity of gas
ρgas = density of gas [kg/m3]
ρair = density of air (normally at NTP - 1.204 [kg/m3])

Molecular weights can be used to calculate Specific Gravity if the densities of the gas and the air are evaluated at the same pressure and temperature.

See also Thermophysical Properties of Air - density, viscosity, critical temperature and pressure, triple point, enthalpi and entropi, thermal conductivity and diffusicity,......

Specific Weight is defined as weight per unit volume . Weight is a force .  The SI unit for specific weight is [N/m3]. The imperial unit is [lb/ft3].

Specific Weight (or force per unit volume) can be expressed as

γ = ρ a g                          (4)

where
γ = specific weight (N/m3], [lb/ft3]
ρ = density [kg/m3], [slugs/ft3]
a g = acceleration of gravity (9.807 [m/s2], 32.174 [ft/s2] under normal conditions)

Specific Weight for Some common Materials

Specific Weight common Materials
ProductSpecific Weight
- γ -
Imperial Units
(lb/ft3)
SI Units
(kN/m3)
Aluminum 172 27
Brass 540 84.5
Carbon tetrachloride 99.4 15.6
Copper 570 89
Ethyl Alcohol 49.3 7.74
Gasoline 42.5 6.67
Glycerin 78.6 12.4
Kerosene 50 7.9
Mercury 847 133.7
SAE 20 Motor Oil 57 8.95
Seawater 63.9 10.03
Stainless Steel 499 - 512 78 - 80
Water 62.4 9.81
Wrought Iron 474 - 499 74 - 78

Example 1: Density of a Golf ball

A golf ball has a diameter of 42 mm and a mass of 45 g. The volume of the golf ball can be calculated as

V = (4/3) π (42 [mm] * 0.001 [m/mm]/2)3 =  3.8 10-5 [m3]

The density of the golf ball can then be calculated as

ρ = 45 [g] * 0.001 [kg/g] / 3.8 10-5 [m3]  = 1184 [kg/m3]

Example 2: Using Density to Identify a Material

An unknown liquid substance has a mass of 18.5 g and occupies a volume of 23.4 ml (milliliter).

The density of the substance can be calculated as

ρ = (18.5 [g] /1000 [g/kg]) / (23.4 [ml] /(1000 [ml/l] * 1000[l/m3]))

= 18.5 10-3 [kg] /23.4 10-6 [m3]  = 790 [kg/m3]

If we look up the densities of some common liquids we find that ethyl alcohol - or ethanol - has a density of 789 kg/m3 . The liquid may be ethyl alcohol!

Example 3: Density to Calculate Volume Mass

The density of titanium is 4507 kg/m3 . The mass of 0.17 m3 volume titanium can be calculated as

m = 0.17 [m3] * 4507 [kg/m3]  = 766.2 [kg]

Note! - be aware that there is a difference between " bulk density" and actual "solid or material density". This may not be clear in the description of products. Always double check values with other sources before important calculations.

Example 4: Specific Gravity of Iron

The density of iron is 7850 kg/m3 . The specific gravity of iron related to water with density 1000 kg/m3 is

SG(iron) = 7850 [kg/m3] / 1000 [kg/m3]  = 7.85

Example 5: Specific Weight of Water

The density of water is 1000 kg/m3 at 4 °C (39 °F).

The specific weight in SI units is

γ = 1000 [kg/m3] * 9.81 [m/s2] = 9810 [N/m3] = 9.81 [kN/m3]

The density of water is 1.940 slugs/ft3 at 39 °F (4 °C).

The specific weight in Imperial units is

γ = 1.940 [slugs/ft3] * 32.174 [ft/s2] = 62.4 [lb/ft3]

Sponsored Links

Related Topics

Basics

Basic engineering data. SI-system, unit converters, physical constants, drawing scales and more.

Beams and Columns

Deflection and stress in beams and columns, moment of inertia, section modulus and technical information.

Densities

Densities of solids, liquids and gases. Definitions and convertion calculators.

Fluid Mechanics

The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.

Material Properties

Properties of gases, fluids and solids. Densities, specific heats, viscosities and more.

Mechanics

The relationships between forces, acceleration, displacement, vectors, motion, momentum, energy of objects and more.

Statics

Forces acting on bodies at rest under equilibrium conditions - loads, forces and torque, beams and columns.

Related Documents

Acceleration of Gravity and Newton's Second Law

Acceleration of gravity and Newton's Second Law - SI and Imperial units.

Acceleration Units Converter

Converting between units of acceleration.

Acetone - Density and Specific Weight

Online calculator, figures and tables showing density and specific weight of acetone at temperatures ranging from -95 to 275 °C (-138 to 530 °F) at atmospheric and higher pressure - Imperial and SI Units.

Acetone - Thermophysical Properties

Chemical, physical and thermal properties of acetone, also called 2-propanone, dimethyl ketone and pyroacetic acid. Phase diagram included.

Air - Density vs. Pressure and Temperatures

Air density at pressure ranging 1 to 10 000 bara (14.5 - 145000 psi) and constant selected temperatures.

Alcohols and Carboxylic Acids - Physical Data

Molweight, melting and boiling point, density, pKa-values, as well as number of carbon and hydrogen atoms in molecules are given for 150 different alcohols and acids.

Ammonia Gas - Density vs. Temperature and Pressure

Online calculator with figures and tables showing density and specific weight of ammonia for temperatures ranging -50 to 425 °C (-50 to 800 °F) at atmospheric and higher pressure - Imperial and SI Units.

Argon - Density and Specific Weight

Online calculator, figures and tables showing density and specific weight of argon, Ar, at varying temperature and pressure - Imperial and SI Units.

Baume's Hydrometer

Liquid density with Degree Baume vs. Specific Gravity.

Benzene - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and table showing density and specific weight of benzene, C6H6, at temperatures ranging from 5 to 325 °C (42 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.

Benzene - Thermophysical properties

Chemical, physical and thermal properties of benzene, also called benzol. Phase diagram included.

Butane - Density and Specific Weight vs. Temperature and Pressure

Online calculators, figures and tables showing density and specific weight of liquid and gaseous butane, C4H10, at varying temperarure and pressure, SI and Imperial units.

Cauchy Number

Introduction to the Cauchy Number.

Centrifugal Pumps - Viscosity Influence

Hydrodynamic losses through pumps depends on fluid viscosities.

Compression and Expansion of Gases

Isothermal and isentropic gas compression and expansion processes.

Crude Oil - Density vs. Temperature

Variations in crude oil density are shown as function of temperatur, together with volume correction factors.

Crude Oil Viscosity vs. Gravity

Viscosity at 20°C/68°F and 50°C/122°F for more than 120 crudes is shown as function of specific gravity@15°C/60°F.

Densities of Aqueous Solutions of Inorganic Chlorides

Changes in density of aqueous solutions with changes in concentration at 20°C. Density of inorganic chlorides in water is plotted as function of wt%, mol/kg water and mol/l solution.

Densities of Aqueous Solutions of Inorganic Potassium Salts

Changes in density of aqueous solutions with changes in concentration at 20°C. Density of potassium salts in water is plotted as function of wt%, mol/kg water and mol/l solution.

Densities of Aqueous Solutions of Inorganic Sodium Salts

Changes in density of aqueous solutions with changes in concentration at 20°C. Density of inorganic sodium salts in water is plotted as function of wt%, mol/kg water and mol/l solution.

Densities of Aqueous Solutions of Organic Acids

Changes in density of aqueous solutions with changes in concentration at 20°C. Density of acetic acid, citric acid, formic acid, D-lactic acid, oxalic acid and trichloroacetic acid in water is plotted as function of wt%, mol/kg water and mol/l solution.

Densities of common Products

Densities of common products - Imperial and SI-units.

Density Converter

Online density converter with commonly used units.

Density of Aqueous Solutions of Organic Substances as Sugars and Alcohols

Changes in density of aqueous solutions with changes in concentration at 20°C. Density of some sugars, alcohols and other organic substances in water is plotted as function of wt%, mol/kg water and mol/l solution.

Density of Aqueous Solutions of some Inorganic Substances

Changes in density of aqueous solutions with changes in concentration at 20°C. Density of inorganic substances in water is plotted as function of wt%, mol/kg water and mol/l solution.

Dirt and Mud - Densities

Densities - pound per cubic foot and kilograms per cubic metre - of dirt and mud.

Ditch Filling Materials - Densities

Weight or density of ditch filling materials.

Energy Equation - Pressure Loss vs. Head Loss

Calculate pressure loss - or head loss - in ducts, pipes or tubes.

Engineering Materials - Properties

Some typical properties of engineering materials like steel, plastics, ceramics and composites.

Ethane - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of ethane, C2H6, at varying temperature and pressure - Imperial and SI Units.

Ethylene - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of ethylene, C2H4, at varying temperature and pressure - Imperial and SI Units.

Ethylene - Thermophysical Properties

Chemical, physical and thermal properties of ethylene, also called ethene, acetene and olefiant gas. Phase diagram included.

Fuel Oils - Densities vs. Temperature

Variations in fuel oils density as function of temperatur, together with volume correction factors.

Fuels - Densities and Specific Volumes

Densities and specific volumes fuels like anthracite, butane, gasoil, diesel, coke, oil, wood and more.

Gases - Specific Gravities

Specific gravities of air, ammonia, butadiene, carbon dioxide, carbon monoxide and some other common gases.

Gravity Heating System

The density difference between hot and cold water is the circulating force in a self circulating gravity heating system.

Heavy Water - Thermophysical Properties

Thermodynamic properties of heavy water (D2O) like density, melting temperature, boiling temperature, latent heat of fusion, latent heat of evaporation, critical temperature and more.

Helium - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of helium, He, at varying temperature and pressure - Imperial and SI Units.

Hydrocarbon Mixtures - Average Boiling Points vs. Gravity and Molecular Weights

Formulas and examples of calculation of boiling point of hydrocarbon mixtures from gravity and molecular weight.

Hydrocarbon Mixtures - Molecular Weight vs. Gravity and Average Boiling Point

Formulas and examples of calculation of average molecular weight of hydrocarbon mixtures from gravity and average boiling point, achieved from distillation data.

Hydrocarbons - Physical Data

Molweight, melting and boiling point, density, flash point and autoignition temperature, as well as number of carbon and hydrogen atoms in each molecule for 200 different hydrocarbons.

Hydrocarbons, Linear Alcohols and Acids - Densities

Density of hydrocarbons like alcohols and acids as function of carbon number at 20°C / 68°.

International Standard Atmosphere

International standard atmosphere in elevation -2000 to 30000 metre - pressure, temperature, density, viscosity, thermal conductivity and velocity of sound.

Jet Fuel - Density vs. Temperature

Variations in jet fuel density as function of temperatur, together with volume correction factors.

Levers

Use levers to magnify forces.

Liquids - Densities vs. Pressure and Temperature Change

Densities and specific volume of liquids vs. pressure and temperature change.

Liquids - Specific Gravities

Specific gravities of liquids like alcohol, oils, benzene, water and many more.

Liquids - Specific Gravities

Specific gravities for common fluids like acetone, alcohol, turpentine, oil and more.

Lubricating Oil - Densities vs. Temperature

Variations in lubricating oil density as function of temperatur, together with volume correction factors.

Mach Number

An introduction to the Mach Number.

Mass vs. Weight

Mass vs. weight - the Gravity Force.

Mercury - Thermodynamic Properties

Properties of saturated liquid Mercury - Hg - density, specific heat capacity, kinematic viscosity, thermal conductivity and Prandtl number.

Methane - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of methane, CH4, at temperatures ranging from -160 to 725 °C (-260 to 1300 °F) at atmospheric and higher pressure - Imperial and SI Units.

Methanol - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of methanol,CH3OH, at varying temperature and pressure - Imperial and SI Units.

Methanol Freeze Protected Heat Transfer Liquids

Freezing and flash points for methanol or methyl based heat-transfer fluids or brines.

Minerals and other Materials - Specific Gravities

Specific gravities for minerals and other materials.

Natural Gas - Pipe Sizing Calculator

Calculate capacities and dimensions of natural gas pipe lines.

Nitrogen - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of nitrogen, N2, at temperatures ranging from -175 to 1325 °C (-280 to 2400 °F) at atmospheric and higher pressure - Imperial and SI Units.

Nitrogen - Thermal Diffusivity vs. Temperature and Pressure

Figures and tables showing thermal diffusivity of nitrogen at varying temperarure and pressure, SI and Imperial units.

Organic Sulfur Compounds - Densities

Liquid density of different kinds of organic sulfur compounds with varying carbon number (20°C/68°F). Comparison of thiols, sulfides, disulfides and thiophenes.

Ounces and Pounds vs. Grams

Converting ounces (ozs.) and pounds (lbs.) to grams (g).

Oxygen - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of oxygen, O2, at varying temperature and pressure - Imperial and SI Units.

Pentane - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and table showing density and specific weight of pentane, C5H12, at temperatures ranging from -130 to 325 °C (-200 to 620 °F) at atmospheric and higher pressure - Imperial and SI Units.

Pitot Tubes

Pitot tubes can be used to measure fluid flow velocities by measuring the difference between static and dynamic pressure in the flow.

Porosity

Volume not occupied by solid material.

Propane - Density and Specific Weight vs. Temperature and Pressure

Online calculator, figures and tables showing density and specific weight of propane, C3H8, at temperatures ranging from -187 to 725 °C (-305 to 1300 °F) at atmospheric and higher pressure - Imperial and SI Units.

Pumps, Fans and Turbines - Horsepower

British Horse Power as used for pumps, fans and turbines - and how to convert to other units.

Solids - Densities

Densities of selected solids.

Solids and Metals - Specific Gravities

Specific gravity for common solids and metals like aluminum, asbestos, brass, calcium and many others.

STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure

The definition of STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure.

Sugar Solubility in Water

Solubility of sugar in water.

The Ideal Gas Law

The relationship between volume, pressure, temperature and quantity of a gas, including definition of gas density.

Thermoplastics - Physical Properties

Physical properties of thermoplastics like ABS, PVC, CPVC, PE, PEX, PB and PVDF.

Toluene - Density and Specific Weight vs. Teemperature and Pressure

Density and specific weight of liquid toluene.

Total and Partial Pressure - Dalton's Law of Partial Pressures

How to calculate total pressure and partial pressures for gas mixtures from Ideal Gas Law.

Troy Weight

Weight unit for preciuos metals like gold and silver.

U-Tube Differential Pressure Manometers

Inclined and vertical u-tube manometers used to measure differential pressure in flow meters like pitot tubes, orifices and nozzles.

Unit Converter with commonly used Units

Common converting units for Acceleration, Area, Density, Energy, Energy per unit mass, Force, Heat flow rate, Heat flux, Heat generation per unit volume and many more.

Universal Gravitational Law

Gravitational attraction between two objects vs. mass of the objects and the distance between them.

Water - Specific Volume vs. Temperature

Online calculator, figures and tables showing Specific Volume of water at temperatures ranging from 0-370 °C and 32 - 700 °F - Imperial and IS Units.

Water - Thermophysical Properties

Thermal properties of water at different temperatures like density, freezing temperature, boiling temperature, latent heat of melting, latent heat of evaporation, critical temperature and more.

Wood Species - Densities

Densities of various wood species - apple, ash, cedar, elm and more.

Yield Structure of Crude Oils with Increasing Density of Crude

Yields of different crude oil distillation cuts are plotted as function of whole crude specific gravity. Fractions based on European and North American markets, and the typical differences in crude oil fractionation in the two markets are also shown.

Sponsored Links

Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.