Engineering converters
Specific Volume Converter
Convert m³/kg, ft³/lb and the reciprocal density units they invert to.
Result
16.0185 ft³/lb
1 m³/kg = 16.0185 ft³/lb
Specific volume is the reciprocal of density, so density units convert through 1 ÷ value. A value of zero has no reciprocal and shows a dash.
All units for this value
| Unit | Symbol | Value |
|---|---|---|
| Cubic meter per kilogram | m³/kg | 1 |
| Liter per kilogram | L/kg | 1000 |
| Cubic centimeter per gram | cm³/g | 1000 |
| Liter per gram | L/g | 1 |
| Cubic foot per pound | ft³/lb | 16.0185 |
| Cubic inch per pound | in³/lb | 27679.9 |
| Cubic foot per slug | ft³/slug | 515.379 |
| US gallon per pound | gal/lb | 119.826 |
| Kilogram per cubic meter | kg/m³ | 1 |
| Gram per cubic centimeter | g/cm³ | 0.001 |
| Pound per cubic foot | lb/ft³ | 0.062428 |
About this calculator
Specific volume measures how much space a given mass of a substance occupies, the reciprocal of density. This converter switches between units like cubic metres per kilogram and cubic feet per pound, and also converts directly to and from familiar density units like kilograms per cubic metre through that reciprocal relationship.
How it works in plain English
Specific volume and density describe the same physical relationship between mass and volume, just inverted: density is mass divided by volume, while specific volume is volume divided by mass. Because of that, a substance with a high density has a low specific volume, and vice versa. The converter uses cubic metres per kilogram as its common anchor for the volume-per-mass units, multiplying and dividing by fixed factors the same way any other converter does.
When you choose a density unit, like kilograms per cubic metre or pounds per cubic foot, as either the from or to selection, the converter takes a reciprocal step: it treats that unit's value as 1 divided by the entered number times the unit's density factor. This means converting 2 kg/m³ of specific volume input into density terms involves inverting the number rather than simply rescaling it, since specific volume and density move in opposite directions as a substance gets denser or lighter.
Because a reciprocal of zero is undefined, entering zero when a density unit is involved produces no meaningful result, and the converter shows a dash instead of a number in that case. Choose your source and target units from the from and to menus, enter a value, and the result appears immediately, backed by a full table of every unit, a precision control, and a swap button to reverse the conversion direction.
The formula
- value_in_target = value_in_source × (source factor to m³/kg) ÷ (target factor to m³/kg)
- 1 ft³/lb = 0.062428 m³/kg
- 1 cm³/g = 0.001 m³/kg
- 1 gal (US)/lb = 0.008345 m³/kg
- Density reciprocal: specific volume (m³/kg) = 1 ÷ density (kg/m³)
- 0 has no reciprocal, so density-based results show a dash
Worked example
Suppose steam has a specific volume of 0.4 m³/kg and you want to know the equivalent density in kilograms per cubic metre. Because density is the reciprocal of specific volume, divide 1 by the value: 1 ÷ 0.4 = 2.5 kg/m³. This single reciprocal step replaces the usual multiply-then-divide process used for other volume-per-mass units.
Entering 0.4 into the m³/kg field with kg/m³ selected as the target shows 2.5 kg/m³ immediately. The full unit table displayed alongside it also confirms the same 0.4 m³/kg equals about 6.4072 ft³/lb, calculated using the direct volume-per-mass factor rather than a reciprocal, since both are specific volume units.
Common specific volume unit equivalents
| Unit | Equal to (m³/kg) |
|---|---|
| 1 m³/kg | 1 |
| 1 L/kg | 0.001 |
| 1 cm³/g | 0.001 |
| 1 L/g | 1 |
| 1 ft³/lb | 0.062428 |
| 1 in³/lb | 0.0000361273 |
| 1 ft³/slug | 0.0019403 |
| 1 gal (US)/lb | 0.008345 |
| 1 kg/m³ (reciprocal) | 1 ÷ value |
| 1 g/cm³ (reciprocal) | 1 ÷ (value × 1,000) |
| 1 lb/ft³ (reciprocal) | 1 ÷ (value × 16.018463) |
Standard unit definitions
Frequently asked questions
Why does the converter treat some units as reciprocals instead of simple factors?
Units like kilograms per cubic metre and pounds per cubic foot measure density, mass over volume, while specific volume measures the inverse, volume over mass. Simply multiplying or dividing by a fixed factor would give the wrong answer between these two families, so the converter inverts the number, 1 divided by the value, whenever a density unit is involved.
What does it mean when the result shows a dash instead of a number?
A dash appears when the entered value is zero and the conversion involves a reciprocal step, since dividing 1 by zero has no defined answer. Zero specific volume or zero density doesn't correspond to any real physical substance, so the converter shows a dash rather than an incorrect or misleading number.
Where is specific volume used instead of density?
Specific volume is common in thermodynamics and steam tables, where it's often more convenient to describe how much volume a fixed mass of a gas or vapor occupies as pressure and temperature change. Refrigeration, HVAC, and power plant engineering calculations frequently use cubic metres or cubic feet per kilogram or pound for this reason.
Can I convert directly between two specific volume units without going through density?
Yes. When both the from and to units are volume-per-mass units, like cubic metres per kilogram and cubic feet per pound, the converter uses the standard multiply-then-divide process through its common anchor, without any reciprocal step. The reciprocal calculation only applies when a density-style unit is one of the two selections.
How precise are the converted results?
Conversions use exact defined factors, such as 0.062428 for cubic feet per pound, so results are as accurate as the number of decimal places you choose to display. The precision control lets you widen or narrow that display, which is useful when comparing closely matched specific volume readings.
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