Crude oil barrels-to-tonnes converter and cargo value calculator
Two calculators built for Nigerian crude: a volume and mass converter that uses each grade's own density instead of a world-average factor, and a cargo value calculator based on a benchmark price and a differential.
Barrels, tonnes and cubic metres converter
How many barrels are in a metric tonne of crude depends on its density. The common factor of 7.33 barrels per tonne is a world average;1 OPEC uses 7.394 for Nigeria,2 and individual grades range from about 6.7 to nearly 8.
Cargo value calculator
Nigerian crude is priced as a benchmark plus or minus a differential (see pricing). Enter your own benchmark price — we do not supply live prices — and a differential to see the FOB value of a cargo and the effect of each dollar of differential.
Illustrative arithmetic only. Actual contract value depends on the bill of lading quantity, the pricing window, and the contract's own freight, insurance, financing and demurrage terms.
Method and limits
API gravity is defined by the relationship SG = 141.5 ÷ (API + 131.5), where SG is specific gravity at 60 °F.3 We convert specific gravity to density using the density of water at 60 °F (999.016 kg/m³) and use 6.2898 barrels per cubic metre.1 So barrels per tonne = (1000 ÷ (SG × 999.016)) × 6.2898.
- API gravity is defined at 60 °F; many contracts and European statistics use density at 15 °C. The two are close but not identical, and commercial measurement applies the volume-correction tables of the relevant petroleum measurement standards.
- Preset gravities are published assay or typical values (see the grade database for each source). Actual cargoes vary: use the figure on the cargo's quality certificate for any commercial calculation.
- The result is mass in vacuum; commercial weight in air is very slightly lower.
- Adding freight and insurance to an FOB value gives only an indicative delivered cost. What each delivery basis actually includes is set out in FOB and CIF explained, and the grade comparison tool shows barrels per tonne alongside the other qualities of each stream.
Sources
- BP / Energy Institute Statistical Review of World Energy — Approximate conversion factors IndustryWorld-average approximations.
- OPEC — Annual Statistical Bulletin 2025 OfficialExport series may include lease condensate and oil in transit.
- U.S. Energy Information Administration — Glossary: API gravity Government
Last reviewed 18 September 2026. Found an error? Tell us — see our methodology and corrections policy.