Calculator
Example data table
Typical densities are approximate and vary by blend, sulfur, and temperature.
| Fuel | Typical density at 15°C (kg/m³) | Typical α (per °C) |
|---|---|---|
| Gasoline | ~740 | ~0.00095 |
| Diesel | ~840 | ~0.00083 |
| Jet A | ~805 | ~0.00099 |
| Kerosene | ~810 | ~0.00099 |
| Ethanol | ~789 | ~0.00110 |
| Biodiesel | ~880 | ~0.00080 |
Formula used
- From mass and volume:
ρ = m / V - From specific gravity:
ρ = SG × ρwater(uses 999.016 kg/m³) - From API gravity:
SG = 141.5 / (API + 131.5), thenρ = SG × ρwater - Temperature adjustment:
ρ₂ = ρ₁ / (1 + α (T₂ − T₁))
How to use this calculator
- Select a method: Mass & Volume, SG, API, or Typical Fuel Value.
- Enter the required inputs for that method and choose your output unit.
- Optional: enter input and target temperatures to correct density.
- Pick a default coefficient or enter a custom α value.
- Press Calculate to view density and intermediate values.
- Use the CSV or PDF buttons to save your results.
Fuel density guide
1) What fuel density tells you
Fuel density is mass per unit volume. It connects how much fuel you can carry, pump, or store to the actual mass delivered. It also supports custody transfer, blending checks, and estimating payload limits for transport and flight planning. For example, 50 L of diesel at about 840 kg/m³ is roughly 42 kg, while 50 L of gasoline at about 740 kg/m³ is about 37 kg.
2) Reference temperatures used in practice
Density changes with temperature, so many specifications reference a standard temperature. A common reference is 15°C (and in some petroleum contexts, 60°F). This page lets you enter an input temperature and a target temperature so you can compare readings taken on different days.
3) Typical density ranges for common fuels
Typical values help you sanity-check results. Gasoline often falls near 720–770 kg/m³, diesel near 820–860 kg/m³, and Jet A near 780–820 kg/m³ around 15°C. Biodiesel can be higher, often near 860–900 kg/m³. Blends can move these numbers.
4) Using mass and volume for highest control
The most direct method is ρ = m/V. If your tank scale shows 25 kg and your metered volume is 30 L, then V = 0.03 m³ and ρ = 25/0.03 = 833.33 kg/m³. This is close to diesel, which is a useful cross-check.
5) Converting from specific gravity
Specific gravity (SG) is a ratio relative to water. This calculator uses water density about 999.016 kg/m³ for the reference. If SG = 0.84, then density is about 0.84 × 999.016 = 839.17 kg/m³. That aligns with typical diesel values.
6) Reading API gravity the right way
API gravity is common for petroleum liquids. The calculator converts API to SG using SG = 141.5/(API + 131.5). For API 35, SG ≈ 0.8498 and density ≈ 848.97 kg/m³. Higher API indicates a lighter product and lower density.
7) Temperature correction with α
When temperature rises, volume expands and density decreases. A simple correction is ρ₂ = ρ₁ / (1 + α(T₂ − T₁)). With α = 0.00083 per °C, moving from 15°C to 35°C changes the denominator to 1.0166, so a fuel at 840 kg/m³ becomes about 826.29 kg/m³.
8) Units and reporting tips
The calculator can show kg/m³, kg/L, g/cm³, lb/ft³, and lb per US gallon. Remember: 1 g/cm³ equals 1000 kg/m³ and 1 kg/L equals 1000 kg/m³. Use the CSV export for logs and the PDF export for audits and lab-style summaries.
FAQs
1) What is a “good” density value for diesel?
Many diesel blends near 15°C fall around 820–860 kg/m³. If your value is far outside this range, recheck units, temperature, and whether the fuel is a special blend.
2) Why does density change with temperature?
Most fuels expand as temperature increases. The mass stays the same, but the volume rises, so density drops. The temperature correction uses α to estimate that expansion.
3) Should I use mass and volume or SG/API?
Use mass and volume when you have measured data; it is direct and flexible. Use SG or API when those are the available lab or supplier specifications and you need quick conversion.
4) What α value should I choose?
Start with the default for your fuel type if it is available. If you have a datasheet coefficient for your exact blend and temperature band, enter it as a custom α for better alignment.
5) What does “API 35” mean in density terms?
API 35 converts to SG ≈ 0.8498 and a density near 849 kg/m³ using the built-in water reference. Higher API numbers correspond to lighter, less dense liquids.
6) Is the built-in water density exact?
It is an approximation suitable for typical engineering checks. For precision lab work, use the exact water density matching your reference temperature and standard, then compare against certified methods.
7) Can I export results for documentation?
Yes. After calculation, use the CSV button for spreadsheets and the PDF button for sharing. Exports include inputs, units, density outputs, and a short formulas section.