Skip to main content
ilovecalcs logoilovecalcs.

Other · Live

Fuel cost, trip-ready in seconds.

Plan a road trip’s gas budget. Enter distance, your car’s fuel efficiency, and current pump price; see total cost, fuel needed, and cost per mile or kilometre as you type.

How it worksReal-time

Inputs

Trip details

US imperial: miles, MPG, $/gallon.

mi
MPG
$$/gal

Quick presets

Total cost
$29.02
Fuel needed
8.93 gal
Per distance
$0.1161 /mi

Trip cost

250 mi · 28 MPG

$29.02

Burns about 8.93 gal at $3.25/gal.

$/mi

$0.1161

Total trip cost
$29.02
8.93 gal × $3.25/gal
Fuel needed
8.93 gal
250 ÷ 28
Cost per mi
$0.1161
$29.02 ÷ 250 mi

Field guide

Gas-saving tips

Easy wins

  • Keep tyres at spec

    Under-inflated tyres cost roughly 0.2% efficiency per psi. Check monthly.

  • Avoid hard acceleration

    Smooth, gradual throttle inputs can lift highway MPG by 15–30%.

  • Drop unnecessary weight

    Every extra 45 kg / 100 lb in the trunk shaves about 1% off fuel economy.

  • Use cruise on the highway

    Holding a constant 90–100 km/h (55–62 mph) is the efficiency sweet spot for most cars.

Field guide

How to estimate fuel cost for any trip.

Fuel cost is one of the easiest budget items to forecast — you only need three numbers: how far you’re driving, how efficient your car is, and what fuel costs per unit today. The arithmetic differs slightly between metric and imperial because efficiency is measured the opposite way in each system, but the underlying idea is the same: divide distance by efficiency to get fuel, multiply fuel by price to get cost.

Imperial: miles, MPG, $/gal

fuel_gallons = distance_miles ÷ MPG
total_cost = fuel_gallons × price_per_gallon

Example: a 250-mile trip in a car that does 28 MPG at $3.45/gal:

fuel = 250 ÷ 28 ≈ 8.93 gal
cost = 8.93 × 3.45 ≈ $30.81

Metric: kilometres, L/100km, $/L

Note the inversion: in metric, “efficiency” is actually consumption: litres needed per 100 km. So a lower number is better, opposite to MPG.

fuel_litres = (distance_km × consumption_L_per_100km) ÷ 100
total_cost = fuel_litres × price_per_litre

Same scenario in metric (≈400 km, 8 L/100km, $1.75/L):

fuel = (400 × 8) ÷ 100 = 32 L
cost = 32 × 1.75 = $56.00

Cost per mile / kilometre

Once you have total cost, dividing by distance gives the most useful per-trip number: the per-distance cost. It stays roughly constant for a given car + fuel price combination, which makes it easy to forecast any future trip just by multiplying.

cost_per_distance = total_cost ÷ distance

For the imperial example above: $30.81 ÷ 250 mi ≈ $0.1232/mile. That's a personal “trip rate” that holds until your fuel efficiency or fuel price changes meaningfully.

Gas-saving tips

None of these are individually huge, but they stack. A driver who keeps tyres at spec, anticipates traffic, removes the roof box for highway trips, and uses cruise control on long hauls can realistically cut their per-mile fuel cost by 15–25%.

  • Keep your tyres at spec. Under-inflated tyres lose roughly 0.2% in efficiency for every 1 psi they’re below the door-jamb recommended pressure. Check monthly with a $5 gauge.
  • Avoid sudden braking and hard acceleration. Aggressive driving can drop city MPG by 15–40%. The fastest way to lift it: anticipate traffic so you brake gently and roll back to speed instead of flooring it.
  • Drop unnecessary weight. Every extra 45 kg / 100 lb in the trunk shaves about 1% off fuel economy. A roof box at highway speed can cost 10–25% in MPG from added drag.
  • Use cruise control on the highway. Holding a constant speed is more efficient than the micro-accelerations a human applies. Most cars hit peak MPG between 90–100 km/h (55–62 mph); above that, drag rises with the square of speed.
  • Combine errands. A cold engine consumes significantly more fuel for the first few minutes; one 30-minute trip uses much less fuel than three 10-minute cold-start trips.
  • Service the car on schedule. Old air filters, fouled spark plugs, and worn O₂ sensors all quietly cost MPG. Stick to the manufacturer’s service intervals.
  • Plan around price spikes. Pump prices can swing 5–15% within a single week. If your trip is flexible, refuelling on a Monday or Tuesday morning is statistically the cheapest in most US markets.

Caveats

  • EPA / WLTP figures are optimistic. Most drivers see 5–15% worse than the sticker MPG / L-per-100km in mixed real-world driving. For more accurate trip budgets, use your own observed efficiency (track a few tank-fills) rather than the marketing number.
  • Highway vs. city. Most cars are 20–40% more efficient on the highway than in the city. If your trip is mostly one or the other, use the matching figure from your owner’s manual.
  • Hybrids and EVs. Hybrid MPG varies wildly with conditions; EVs use kWh/mile or kWh/100km, a different calculator entirely (coming soon).