Specific Volume Converter: m³/kg, ft³/lb, L/kg & More

Convert specific volume between m³/kg, L/kg, ft³/lb, cm³/g, gal/lb, and eight units. Whether you need m³/kg to ft³/lb, L/kg to m³/kg, or any SI or imperial unit, this converter uses the SI base (cubic meter per kilogram) for accurate results. Specific volume is the reciprocal of density. Free, runs in your browser—no sign-up required.

What is specific volume?

Specific volume is volume per unit mass—the reciprocal of density (v = 1/ρ). Its dimension is length³/mass (e.g. m³/kg). The SI unit is cubic meter per kilogram (m³/kg). In thermodynamics and process engineering you’ll see L/kg (1 L/kg = 0.001 m³/kg), cm³/g (same as L/kg), and imperial ft³/lb or gal/lb (US and UK). This converter supports eight units. Every value is normalized to m³/kg under the hood.

How specific volume conversion works

Specific volume is volume per unit mass — the inverse of density. The SI unit is cubic meter per kilogram (m³/kg). Convert your value into m³/kg using the source unit’s factor, then divide by the target unit’s factor:

\text{Result} = \text{Value} \times \frac{\text{source (m}^3\text{/kg)}}{\text{target (m}^3\text{/kg)}}

Example: 1 L/kg to m³/kg → 1 × 0.001 ÷ 1 = 0.001 m³/kg (since 1 L = 0.001 m³). Water at 4°C has specific volume about 0.001 m³/kg. The converter supports metric (m³/kg, L/kg, cm³/g) and imperial (ft³/kg, ft³/lb, gal/lb US and UK).

Key Specific Volume Units Explained

Each unit’s factor to m³/kg — what this specific volume converter uses. All are volume/mass; the SI unit is m³/kg, and 1 L/kg = 0.001 m³/kg (1 liter = 0.001 m³).

Cubic meter/kilogram (m³/kg)

Factor: 1 (SI base unit)

The SI derived unit for specific volume. Used in thermodynamics, fluid mechanics, and HVAC. For water at 4°C, v ≈ 0.001 m³/kg.

Cubic centimeter/gram (cm³/g)

Factor: $1\,\text{cm}^3/\text{g} = 0.001\,\text{m}^3/\text{kg}$

Same scale as L/kg: 1 cm³/g = 1 L/kg = 0.001 m³/kg. Common in chemistry and materials (reciprocal of density in g/cm³).

Liter/kilogram (L/kg)

Factor: 1 L/kg = 0.001 m³/kg

Widely used in process engineering and refrigeration. 1 L = 0.001 m³, so 1 L/kg = 0.001 m³/kg. Steam tables often use m³/kg or L/kg.

Cubic foot/pound (ft³/lb)

Factor: 1 ft³/lb ≈ 0.06243 m³/kg

Common in US engineering and HVAC (e.g. specific volume of air, steam). 1 ft³/lb = 0.0283168 m³ ÷ 0.453592 kg ≈ 0.0624 m³/kg.

Gallon (US)/pound

Factor: 1 gal (US)/lb ≈ 0.00835 m³/kg

Used for liquids and some refrigerant tables in the US. US gallon = 0.00378541 m³; 1 gal/lb ≈ 0.00835 m³/kg.

Gallon (UK)/pound

Factor: 1 gal (UK)/lb ≈ 0.01002 m³/kg

UK gallon is larger than US, so 1 gal (UK)/lb gives a larger specific volume than 1 gal (US)/lb. Used in UK and some Commonwealth contexts.

When to use m³/kg vs L/kg vs ft³/lb

m³/kg is the SI unit and is used in thermodynamics (steam tables, refrigerant properties) and fluid mechanics. L/kg and cm³/g are numerically the same (0.001 m³/kg) and are convenient in process engineering and chemistry. ft³/lb is common in US HVAC and refrigeration. gal/lb (US and UK) appears in refrigerant and liquid tables. This converter supports all eight so you can match steam tables, datasheets, and formulas.

Who uses a specific volume converter?

HVAC and refrigeration engineers convert between m³/kg, L/kg, and ft³/lb for refrigerant and steam properties. Process and chemical engineers use L/kg or cm³/g for specific volume in mass-balance and property tables. Students and educators use it to check homework (e.g. “convert 0.001 m³/kg to L/kg”) and to relate v = 1/ρ to real-world units. Liquid water at 4°C has specific volume about 0.001 m³/kg (1 L/kg); steam and gases have much larger values. All conversions run in your browser—no data is sent to a server.

Common specific volume conversions at a glance

Handy reference for m³/kg to ft³/lb, L/kg to m³/kg, and other everyday specific volume conversions.

From	To	Formula	Example
m³/kg	L/kg	× 1000	0.001 m³/kg = 1 L/kg
L/kg	m³/kg	÷ 1000	1 L/kg = 0.001 m³/kg
m³/kg	ft³/lb	÷ 0.06243	0.0624 m³/kg ≈ 1 ft³/lb
ft³/lb	m³/kg	× 0.06243	16 ft³/lb ≈ 1 m³/kg
cm³/g	m³/kg	÷ 1000	1 cm³/g = 0.001 m³/kg

Why cubic meter per kilogram is the SI unit

Specific volume is volume divided by mass, so its dimension is m³/kg in SI. It’s common in thermodynamics (e.g. steam tables, refrigerant properties) and fluid mechanics. Liter per kilogram (L/kg) is numerically convenient since 1 L/kg = 0.001 m³/kg. Imperial units (ft³/lb, gal/lb) use foot or gallon and pound; the converter uses fixed conversion factors so every result is consistent.

Avoiding common mistakes

Don’t confuse specific volume (v = volume/mass, m³/kg) with density (ρ = mass/volume, kg/m³)—they’re reciprocals: v = 1/ρ. So 1000 kg/m³ density → 0.001 m³/kg specific volume. Don’t mix gal (US)/lb and gal (UK)/lb; the UK gallon is larger so UK gal/lb gives a larger specific volume. When steam tables give both density and specific volume, use this converter for v and the Density Converter for ρ. Always convert to one unit (we recommend m³/kg) before plugging into formulas.

Specific Volume Conversion FAQ

? How do I convert m³/kg to ft³/lb?

Multiply m³/kg by about 16.018 to get ft³/lb. So 0.0624 m³/kg ≈ 1 ft³/lb. To convert ft³/lb to m³/kg, divide by 16.018 (or multiply by 0.06243).

? What is the relationship between specific volume and density?

Specific volume is the reciprocal of density: v = 1/ρ. So 1 m³/kg = 1/(1 kg/m³). If density is 1000 kg/m³, specific volume is 0.001 m³/kg (1 L/kg). Use the density converter for mass/volume; use this converter for volume/mass.

? Why is L/kg the same as cm³/g?

1 L = 1000 cm³ and 1 kg = 1000 g, so 1 L/kg = 1000 cm³ / 1000 g = 1 cm³/g. Both equal 0.001 m³/kg. So numerically, L/kg and cm³/g are the same; the converter treats them with the same factor to m³/kg.

? When is gallon per pound used?

Gallon per pound (gal/lb) is used in US and UK contexts for specific volume of liquids or in refrigerant tables. US gallon per pound is smaller than UK gallon per pound because the US gallon is smaller. This converter supports both.

? What is the SI unit for specific volume?

Cubic meter per kilogram (m³/kg). Specific volume is volume per unit mass, so in SI (volume in m³, mass in kg) the coherent unit is m³/kg. It’s the reciprocal of density (kg/m³): v = 1/ρ. This converter uses m³/kg as the base for all eight units.

? How do I convert specific volume to density?

Take the reciprocal: density ρ = 1/v. So if v = 0.001 m³/kg, then ρ = 1000 kg/m³. Convert v to your desired unit first with this converter, then take 1/v to get density in the corresponding mass/volume unit. Or use the Density Converter for direct density conversion.

Specific Volume Conversion Tool