Fuel & Gas Converter

This page combines two practical calculators in one place. The mass ↔ volume tab answers questions like 1 liter diesel to kg and 1 kg oil to liter using standard fuel densities. The fuel economy tab converts mpg, L/100 km, and km/L for comparing window-sticker ratings across countries.

Fleet managers, mechanics, and importers often need a quick gas converter without spreadsheets. Diesel is bought by volume (liters) but invoiced by weight in some markets; engine oil may be quoted in kg on bulk orders but dispensed in liters at the pump. This tool applies published density figures so you can cross-check receipts, customs declarations, and tank capacity planning.

Everything runs locally in your browser — fuel purchase data is never uploaded.

Mass and volume link through density: mass (kg) = volume (L) × density (kg/L). For standard automotive diesel at roughly 0.832 kg/L, 1 liter diesel to kg equals about 0.832 kg. Reversing the formula, 1 kg oil to liter (or diesel) divides mass by density — one kilogram of diesel ≈ 1.20 liters.

Engine oil densities vary by grade and temperature. A typical multi-grade oil averages near 0.88 kg/L, so a liter oil to kg conversion yields about 0.88 kg per liter, and a kg to liters oil calculator result for 5 kg is roughly 5.68 liters. Always use the density printed on the product sheet for legal or billing disputes; this tool uses industry-average constants for everyday estimates.

Petrol (gasoline) is lighter — about 0.745 kg/L — so the same volume weighs less than diesel. Select the fuel type in the calculator before converting so the output matches the product you handle.

Fuel economy measures distance per fuel consumed (mpg, km/L) or fuel consumed per distance (L/100 km). US EPA labels use mpg; Europe and most of Asia use L/100 km. They invert each other — a efficient car has high mpg but low L/100 km.

The economy tab uses the standard bridge formula for US mpg: L/100 km = 235.214583 ÷ mpg. UK imperial gallons produce higher mpg numbers for the same car because the gallon is larger. When comparing a imported brochure to a local rating, convert both to L/100 km first, then compare.

Fuel economy conversion is separate from mass ↔ volume conversion. A vehicle that uses CNG or diesel still has an economy rating, but kg and liter swaps depend on fuel density, not km/L.

Searches for CNG conversion, convert petrol to CNG, or conversion of petrol car to CNG usually refer to retrofitting a gasoline vehicle with a compressed natural gas (CNG) kit — not a simple unit swap. That process involves approved cylinders, pressure regulators, injectors, and government inspection. It is unrelated to multiplying liters by density, but owners often look up both topics in the same session when comparing running costs.

Compressed natural gas conversion costs vary by country, cylinder size, and kit brand — often quoted as a CNG conversion price including hardware and labor. A car CNG conversion must be performed at a certified workshop; DIY cylinder installs are unsafe and illegal in most jurisdictions.

CNG fuel conversion in energy terms: about 1 kg CNG delivers similar usable energy to roughly 1.3–1.5 liters of petrol, depending on methane grade and engine efficiency — a rule of thumb for cost comparison, not a density formula. CNG stored in cylinders is a gas under high pressure, so it does not have a fixed “kg per liter” like liquid diesel. Use the mass ↔ volume tab for liquid fuels (diesel, petrol, LPG, oil); treat CNG economy as a separate fleet calculation.

If you are researching convert car to CNG or CNG vehicle conversion, contact your national transport authority for approved kit lists, warranty implications, and resale rules before modifying a petrol car to CNG.

LPG (propane/butane mix) is stored as a liquid under moderate pressure and has a defined liquid density near 0.508 kg/L — suitable for the mass ↔ volume calculator. CNG is predominantly methane stored at much higher pressure as a gas; mass is measured at the dispenser in kg, but there is no meaningful “liters of CNG” equivalent without specifying pressure and temperature.

Diesel and petrol remain the default for the 1 liter diesel to kg calculator use case because bulk delivery notes and customs forms almost always cite liquid volume plus temperature-corrected density.

A tanker delivers 10,000 L of diesel. The weighbridge ticket reads 8,320 kg. Check: 10,000 × 0.832 = 8,320 kg — the delivery matches standard density. If weight is more than 2% off, request the supplier’s temperature-corrected density certificate before signing.

For oil drums labelled 208 L, expected mass ≈ 208 × 0.88 = 183 kg. Use the oil preset in the calculator and enter liters to verify drum weight on a forklift scale.

Densities shift with temperature: fuel expands when warm, so a liter at 30 °C weighs slightly less than at 15 °C. Commercial fuel trade uses ASTM tables to correct volume to 15 °C reference. This tool uses fixed averages suitable for estimates, homework, and quick field checks — not custody transfer billing.

Biodiesel blends, winter diesel, and high-sulfur variants differ from 0.832 kg/L. Select petrol for gasoline, diesel for diesel, and oil for lubricants; do not mix presets when auditing two products on one invoice.