Fuel cost scales directly with how much you drive and directly with gas price, and inversely with MPG: doubling your commute or halving your MPG both double your fuel bill. This calculator turns your own numbers into a real budget instead of a rough guess, and lets you see exactly what a lower-MPG vehicle would cost you at the same mileage.
Last reviewed September 2026
| Period | Miles | Gallons | Vehicle A cost |
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This calculator starts with how much you drive, either miles per day or miles per week, and converts it to a yearly total (52 weeks), then divides by 12 for a monthly figure and by 7 for a daily figure, so every period is consistent with the others. It divides your monthly and yearly miles by your vehicle's MPG to get gallons used, then multiplies by your gas price to get a dollar cost for each period. Turning on the Vehicle B comparison runs the exact same miles and gas price through a second MPG, so the only thing that changes is the vehicle.
Fuel cost scales directly with miles: driving twice as much costs twice as much in gas, holding MPG and gas price constant. A 30-mile daily commute costs about $4.80 a day in a 28 MPG car at $4.48 a gallon; a 60-mile commute in the same car costs about $9.60 a day, exactly double.
MPG moves cost the other direction: a higher MPG vehicle uses fewer gallons for the same miles. At 910 miles a month and $4.48 a gallon, a 35 MPG economy car costs about $116.48 a month while a 18 MPG pickup truck costs about $226.49 a month for the identical driving, a difference of about $110 a month for the same route.
Gas price is the most volatile input: the U.S. Energy Information Administration's own weekly data shows the national average moved from $4.157 to $4.478 a gallon in just three weeks (week of 09/07/2026 to week of 09/21/2026), a change of over 7%. This calculator defaults to the latest published national average but is fully editable, since your local price is what actually appears on your receipt.
National average gas price: U.S. Energy Information Administration, "Gasoline and Diesel Fuel Update", gasoline release date September 22, 2026 (next release September 29, 2026). The published U.S. regular gasoline price table reads, for the three most recent weeks: week of 09/07/2026 $4.157/gallon, week of 09/14/2026 $4.319/gallon, week of 09/21/2026 $4.478/gallon (up $0.159 from the week prior). This calculator's default uses the most recent published figure, $4.478/gallon (displayed as $4.48). Vehicle MPG defaults by vehicle type: reused verbatim from this site's own Road Trip Cost Calculator, itself sourced to DOE fueleconomy.gov (Economy Car 35 MPG, Mid-Size Car 28 MPG, SUV 24 MPG, Minivan 22 MPG, Pickup Truck 18 MPG, Hybrid 45 MPG).
Not included in this build: an EV cost-per-mile comparison was considered for this page but left out. This site's existing EV charging figure ($0.16/kWh home-charging average, used by the Road Trip Cost Calculator) is not an EIA-sourced residential electricity rate, and this build's own live check of EIA's Electric Power Monthly (Table 5.3, average residential price of electricity, most recent month published: July 2026, 18.31 cents/kWh) still lacks a live-sourced average EV miles-per-kWh figure to pair with it. Rather than estimate that figure, it is left out of this page; see the EV Charging Cost Calculator for a dedicated EV-vs-gas comparison.
Planning more than your fuel cost? See also the Road Trip Cost Calculator, the Auto Loan Calculator, and the Personal Budget Calculator to see fuel cost alongside the rest of your monthly budget.