How to use this calculator
- Enter the one-way miles from your map app, choose round trip or one way, and enter your car’s MPG.
- Keep EIA’s weekly U.S. average, pick your region (or your state or city if EIA reports it), or type the price you expect to pay.
- Enter how many people are in the car and whether the driver pays a share. Add tolls and parking if you want them split too.
THE CONTEXT BEHIND THE COST
Gas money is easier to agree on before the drive.
Your map app gives the miles, but not how many gallons the trip will burn. Miles divided by MPG gives the gallons; gallons times the price per gallon gives the gas cost. That is all this calculator does, and it shows each step.
The split is a choice. You can divide the gas among everyone, the driver included, or let the passengers cover it because the driver brings the car. The calculator shows both, so the group can agree on one before anyone fills up.
The price matters as much as the MPG. The calculator opens on EIA’s latest weekly U.S. average and lets you choose one of EIA’s regional averages, or one of the nine states and ten cities it reports, for the same week, each labeled with its date. On a long drive you’ll buy gas in more than one place, so use the average for the area where you’ll fill up most, or type the price you expect.
Cost examples
How much gas does a round trip cost?
Round-trip gas at EIA’s U.S. average of $4.465 a gallon for the week of September 28, 2026, the price this calculator opens on. Distances and MPG are examples, not typical trips.
| Trip | At 25 MPG | At 30 MPG | At 40 MPG |
|---|---|---|---|
| 100 miles each way | $35.72 | $29.77 | $22.33 |
| 250 miles each way | $89.30 | $74.42 | $55.81 |
| 500 miles each way | $178.60 | $148.83 | $111.63 |
Splitting the gas
A 150-mile-each-way round trip at 30 MPG uses 10 gallons, or $44.65 at that price. Four people splitting it, driver included, pay $11.16 each; if the three passengers cover it, each pays $14.88.
A worked example
With the illustrative inputs used when this tool first opens:
Your 500-mile round trip: $74.42 in gasMiles = 250 one way × 2 = 500 miles.
Gallons = 500 miles ÷ 30 MPG = 16.67 gallons.
Gas = 500 miles ÷ 30 MPG × $4.465 = $74.42.
Each share = $74.42 ÷ 3 people paying = $24.81.
Cost per mile = $4.465 ÷ 30 MPG = $0.1488.
Miles per $20 = $20 ÷ $4.465 × 30 MPG = 134.4 miles.
Generated with the same calculation engine as the interactive result.
Formulas you can inspect
Miles driven = one-way miles × 2 for a round trip, or one-way miles for a one-way trip.
Gallons = miles driven ÷ MPG. Gas cost = miles driven ÷ MPG × price per gallon (the same fuel formula the commute and car calculators use).
Trip total = gas cost + tolls and parking entered for the whole trip.
Each share = trip total ÷ people paying, where people paying = everyone in the car, or everyone except the driver.
Cost per mile = price per gallon ÷ MPG. Miles per $20 = $20 ÷ price per gallon × MPG.
Assumptions and limits
- You type the miles; the calculator doesn’t plan routes, check distances or add detours.
- One MPG and one price apply to the whole trip. Real fuel economy changes with speed, load, terrain and weather, and prices change along the way.
- EIA’s weekly prices are averages of Monday retail prices for an area, with all taxes included. They are not the price at a particular station, and they are updated once a week.
- Only gas and the tolls or parking you enter are counted. Wear, maintenance, insurance, depreciation, food and lodging are not. No IRS mileage rate is used.
- Amounts keep full precision until display; shares are rounded to the cent.
Sources for this tool
- U.S. Energy Information Administration: Gasoline and Diesel Fuel Update: regular gasoline, weekly ↗Week of September 28, 2026 · released September 29, 2026 · next release October 6, 2026 · Checked
- FuelEconomy.gov (U.S. Department of Energy and EPA): Find and compare cars ↗Live lookup of EPA fuel economy ratings · Checked
- FuelEconomy.gov (U.S. Department of Energy and EPA): Driving more efficiently ↗Current page (undated) · Checked
- Internal Revenue Service: Standard mileage rates ↗Live reference table; for July 1 to December 31, 2026 (IR-2026-29): 76 cents a mile for business, 23.5 cents for medical or military moving, 14 cents for charity. Page updated July 28, 2026 · Checked
Common questions
How do I calculate the gas cost for a trip?
Divide the miles by your car’s MPG to get gallons, then multiply by the price per gallon. For example, 500 miles ÷ 30 MPG = 16.67 gallons. At EIA’s U.S. average of $4.465 a gallon for the week of September 28, 2026, that’s $74.42. The calculator does the same math and shows each step.
How much will gas cost for a 1,000-mile trip?
At EIA’s U.S. average of $4.465 a gallon for the week of September 28, 2026: $178.60 in a car that gets 25 MPG (40 gallons); $148.83 in a car that gets 30 MPG (33.3 gallons); $127.57 in a car that gets 35 MPG (28.6 gallons). Your MPG and the prices along your route change the answer.
How far will $20 of gas get me?
At EIA’s U.S. average of $4.465 a gallon for the week of September 28, 2026, $20 buys 4.48 gallons. That’s about 112 miles at 25 MPG, 134 miles at 30 MPG and 179 miles at 40 MPG. The calculator shows it for your car and price.
How much gas money should I give for a 2-hour drive?
Turn the time into miles first; your map app shows both. For example, if a 2-hour drive covers 120 miles (an average of 60 mph, used here only as an example), a car that gets 30 MPG burns 4 gallons. At EIA’s U.S. average of $4.465 a gallon for the week of September 28, 2026, that’s $17.86, or $8.93 each if you and the driver split it. If only you pay, it’s the full $17.86.
Should I enter one-way or round-trip miles?
Enter the one-way miles and choose Round trip; the calculator doubles them. For a trip with several stops, add up all the legs and choose One way.
Should the driver pay a share of the gas?
There is no rule; it is the group’s choice. Splitting among everyone treats the drive as shared travel. Letting passengers cover the gas recognizes that the driver supplies the car and its wear. The calculator shows both amounts side by side.
Why not charge the IRS mileage rate?
The IRS standard mileage rates are tax figures for business, medical, military moving and charity deductions. They are not what the gas for a trip costs. If your group also wants to share the wear on the car, agree on an amount openly; this calculator counts gas, tolls and parking only.
Methodology reviewed September 27, 2026. Trip gas cost methodology · Report a correction