The formula
Every calculator on this site is a different presentation of the same equation:
Petrol cost = (Distance ÷ Mileage) × Price per unit
The three inputs must agree on units — kilometres with km/L, miles with MPG, or kilometres with L/100 km. The calculator normalizes everything to a common base unit before applying the price; the user just picks the units they think in.
Unit conversions
- 1 mile = 1.609344 km (international agreement, 1959).
- 1 US gallon = 3.785411784 L. 1 UK gallon = 4.54609 L. The two are different — a US MPG figure does not carry over to UK fuel pricing.
- MPG → km/L: multiply US MPG by 0.4251. Equivalently, 25 US MPG ≈ 10.6 km/L.
- L/100 km → km/L: divide 100 by L/100 km. So 8 L/100km = 12.5 km/L.
Example petrol-price presets
These values are editable examples used to make the calculator usable on first load. They are not live market quotes or guaranteed national averages.
On first load the calculator detects the user's locale and pre-fills an example petrol price for the selected currency:
- Pakistan (PKR): ~ ₨ 280 per litre
- India (INR): ~ ₹ 105 per litre
- Bangladesh (BDT): ~ ৳ 130 per litre
- Sri Lanka (LKR): ~ Rs 365 per litre
- UK (GBP): ~ £ 1.45 per litre
- USA (USD): ~ $ 3.40 per US gallon
- Eurozone (EUR): ~ € 1.70 per litre
- Australia (AUD): ~ A$ 1.85 per litre
- Canada (CAD): ~ C$ 1.55 per litre
- UAE (AED): ~ د.إ 3.10 per litre
- Saudi Arabia (SAR): ~ ﷼ 2.33 per litre
- South Africa (ZAR): ~ R 22.50 per litre
Petrol prices change weekly. Confirm today's rate at your local pump or your country's fuel-price authority before relying on the result for a budget commitment.
Default mileage figures
The vehicle selector preloads illustrative mileage ranges for each segment. Replace these examples with a measured average for your own vehicle whenever possible:
- Bike (motorcycle): 35–65 km/L. Default 50 km/L (mid-range 125cc commuter).
- Scooter: 40–55 km/L. Default 50 km/L (Honda Activa class).
- Car: 9–20 km/L. Default 14 km/L (small sedan / hatch).
- Truck / SUV: 7–13 km/L. Default 10 km/L (mid-size SUV / pickup).
Period projections
The result panel projects daily cost across longer windows by simple multiplication — 30 days for the "monthly" figure, 365 days for the "annual". We don't model weekday/weekend split, holidays, or annual leave because those vary too much per user. Override the distance per day to model a working-days-only commute.
Carpool split
The carpool option divides the total trip cost by the number of riders, including the driver. So 4 carpoolers split a ₨ 200 trip into ₨ 50 each. The math doesn't weight by distance traveled per rider — use the dedicated carpool split calculatorfor that workflow.
Where we're less precise
- We use a single mileage figure for the whole trip. Real-world fuel economy varies with stop-and-go traffic, hill grade, climate-control use, tyre pressure, vehicle age, load, and driving style.
- We assume the petrol price is constant across the trip. For out-of-region road trips, refill prices change.
- We don't model losses from vehicle warm-up on short trips, which can knock 5–10% off the calculated mileage on a sub-2 km commute.
Disclaimer
Estimates only. The calculator is a budgeting and planning tool, not a fleet-management or tax-deduction system. Confirm fuel prices with your local pump and verify mileage against your own fill-up records before relying on the output for business expense reporting.