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Everyday math

Fuel Cost Calculator

Trip fuel cost from distance, mileage and fuel price, plus cost per km and the km/l ↔ mpg conversion.

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Quick answer

Fuel needed = distance ÷ mileage; cost = fuel × price. A 300 km trip at 15 km/l with fuel at ₹100/l needs 20 litres, ₹2,000, or ₹6.67/km. Split it per passenger before the trip, not awkwardly after.

People sharing the cost.

Trip fuel cost
₹2,000
Fuel needed
20 litres
Cost per km
₹6.67

Formulas last verified 2026-10-10. Results are estimates, not financial advice. How we calculate.

Cost per kilometre: the number worth memorising

cost/km = fuel price ÷ mileage

At ₹100/l and 15 km/l, driving costs ₹6.67 per km in fuel alone. That single figure prices any trip instantly, the daily 30 km commute is ₹200, the 600 km weekend is ₹4,000, and it is the honest basis for comparing against a train ticket or a shared cab.

Reference grid (₹ per km)

Mileage ↓ / Price →₹95/l₹100/l₹105/l
10 km/l₹9.50₹10.00₹10.50
15 km/l₹6.33₹6.67₹7.00
20 km/l₹4.75₹5.00₹5.25

Note the asymmetry: improving mileage from 10 to 15 km/l saves ₹3.33/km, while fuel price swings of ₹10 move the cost only ₹0.67/km at 15 km/l. The car (and how it is driven) matters far more than the pump price everyone watches.

Fuel is half the story

The full per-km cost of car ownership adds insurance, maintenance, tyres and depreciation, typically about as much again as fuel for a mid-size car driven 1,000 km/month. Fuel cost answers "what does this trip cost me today?"; total cost answers "should this trip be by car at all?". Keep the two questions separate and both answers get easier.

The electric comparison

The same trip in an EV at 15 kWh/100 km and ₹8/kWh costs about ₹1.33/km including charging losses, roughly a fifth of the petrol figure above. The EV charging calculator computes it for your numbers, and the EV vs petrol comparison puts both side by side over a month of driving. For splitting whatever the trip costs, the percentage calculator handles uneven shares.

Frequently asked questions

How do I calculate fuel cost for a trip?

Fuel needed = distance ÷ mileage; cost = fuel × price per litre. A 300 km trip at 15 km/l with petrol at ₹100/l needs 20 litres and costs ₹2,000, ₹6.67 per km. Add tolls separately; they often rival the fuel on Indian highways.

What mileage figure should I use?

Your real-world figure, not the brochure. Certified test figures (ARAI, EPA, WLTP) run 15–30% optimistic versus mixed driving. The honest method: fill the tank, reset the trip meter, drive normally, refill, km ÷ litres at the second fill is your true mileage. City traffic can halve a highway figure.

How do I convert km/l to mpg?

Multiply km/l by 2.352 for US mpg (15 km/l ≈ 35.3 mpg); divide mpg by the same factor to go back. UK (imperial) mpg uses 2.825. Confusing the two gallons is the classic error, an imperial gallon is 20% larger.

How should we split fuel on a shared trip?

Agree before leaving: total fuel (this calculator) plus tolls and parking, divided by people, the driver's figure is then arithmetic, not negotiation. Splitting only fuel underpays the owner; wear, insurance and depreciation roughly double the true per-km cost of running a car.

Does speed really change fuel consumption?

Substantially. Aerodynamic drag grows with the square of speed: most cars deliver their best economy near 60–80 km/h, and 110 km/h can consume 20–25% more per km than 80. Smooth driving matters too, hard acceleration and braking cycles waste fuel that steady cruising keeps.

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