Fuel Cost Calculator

Introduction

Planning a road trip or daily commute? Knowing your fuel costs in advance helps you budget accurately and compare routes or vehicles. This tool takes three simple inputs — distance, fuel efficiency, and price per litre — and instantly calculates everything you need to know: total fuel required, total trip cost, and cost per 100 kilometres.

It supports both metric (km, litres) and imperial (miles, MPG) units, making it useful for drivers around the world.

The Math Behind the Calculator

Unit Conversion (when using miles/MPG):

• 1 mile = 1.60934 km
• 1 MPG = 0.425144 km/L (US gallon basis)

Core Formulas:

Fuel Needed (L) = Distance (km) / Efficiency (km/L)
Total Cost     = Fuel Needed × Price per Litre
Cost per 100km = (100 / Efficiency) × Price per Litre

Worked Example:

• Trip distance: 400 km
• Car efficiency: 12 km/L
• Fuel price: ৳115 per litre

Fuel Needed = 400 / 12 = 33.33 L
Total Cost  = 33.33 × 115 = ৳3,833
Cost/100km  = (100 / 12) × 115 = ৳958

Real-World Use Cases

Road Trips: Budget your total fuel cost before a long journey. Compare petrol costs for two different route distances to decide which is more economical.

Daily Commute: Calculate Your monthly fuel bill precisely. If your commute is 25 km each way (50 km/day) at 10 km/L and ৳115/L:

• Daily cost = 50/10 × 115 = ৳575
• Monthly cost (22 working days) = ৳12,650

This figure makes it easy to compare against a bus or rideshare pass.

Fleet Management: For delivery businesses, calculate fuel cost per route to price deliveries accurately and maintain margins. Two routes of the same distance can have very different costs depending on urban stop-and-go vs. highway driving efficiency.

Vehicle Comparison: Considering buying a new car? Compare a 12 km/L petrol car vs. an 18 km/L hybrid over 15,000 km/year:

• Petrol: 15,000/12 × 115 = ৳143,750/year
• Hybrid: 15,000/18 × 115 = ৳95,833/year
• Annual saving: ৳47,917

Best Practices & Tips

Real-world efficiency is 10–20% lower than claimed. Manufacturer efficiency numbers are tested under ideal conditions — steady highway speed with no air conditioning. Account for city traffic, AC usage, cargo weight, and tyre pressure. Use your car's trip computer average for more accurate estimates.

Fuel price changes frequently. Check the current local pump price before calculating for accurate estimates. A 10% rise in fuel price has an identical effect to a 10% drop in efficiency.

Cold weather reduces efficiency by up to 20%. Winter fuel consumption is significantly higher due to engine warm-up time, denser cold air in the fuel system, and higher rolling resistance from cold-stiffened tyres.

Use 95-octane vs. 91-octane carefully. Higher octane fuel is not inherently more powerful — it only matters if your engine is tuned to require it. Using premium fuel in a non-premium engine is wasted money.

Frequently Asked Questions

Why is my actual fuel cost higher than the calculator? Real-world factors like aggressive acceleration, air conditioning, heavy loads, headwinds, and stop-and-go traffic all reduce fuel efficiency below the theoretical value. Adjust your km/L input downward to match your real-world observed consumption.

How do I find my car's actual efficiency? Fill your tank completely, reset your trip odometer. Drive normally until you need to refuel, then note the km driven and the litres it takes to fill up. Efficiency = km ÷ litres.

Does this work for electric vehicles? No — EVs use kWh/100km or miles per kWh instead of fuel efficiency. Use an EV-specific cost calculator for electric vehicles.

Can I calculate for a return trip? Simply double the one-way distance in the distance field to get the round-trip total.