Gas / Fuel Cost Calculator
Trip cost = distance ÷ MPG (or L/100km) × fuel price. Supports US gallons, UK gallons, litres. Multi-leg trips, EV comparison. Free.
Gas / Fuel Cost Calculator
Compute trip fuel cost from distance, fuel economy (MPG or L/100km), and fuel price. Supports US gallons, UK gallons, litres. Shows one-way + round-trip cost, per-mile cost, per-person cost (for shared trips), plus EV-equivalent for comparison.
How to Use the Fuel Cost Calculator
Enter trip distance
Use Google Maps for accurate one-way distance. Toggle between miles (US default) and km (EU/Asia default).
Set vehicle fuel economy
From your car's specs or recent fuel logs. Toggle between MPG (US/UK) and L/100km (EU/Asia). The tool normalises internally so any unit combination produces correct cost.
Enter current fuel price
From your most recent receipt, or from a price survey — EIA's weekly retail survey put US regular at USD 4.157/gal in the week of 7 September 2026, and AAA and GasBuddy publish state and station-level prices. European pump prices run far higher per litre because of fuel duty; the European Commission's Weekly Oil Bulletin lists them by country. Toggle USD-per-gallon vs USD-per-litre as appropriate.
Compare to EV equivalent
The EV equivalent assumes 30 kWh per 100 miles — 3.3 mi/kWh, mid-range of the 1.49–4.17 mi/kWh spread of model-year-2024 EVs (US DOE Fact of the Week #1373, December 2024) — at USD 0.18 per kWh, the rounded US residential average of 18.34 ¢/kWh for June 2026 (EIA Electric Power Monthly, Table 5.6.A). Swap in your car's EPA kWh/100 mi rating and your own tariff for a closer figure.
Fuel Cost Math — Distance, MPG, and the EV Comparison
The Universal Formula
Fuel cost is one of the simplest financial calculations in personal travel: distance × (fuel price ÷ fuel economy). A 300-mile trip at 28 MPG on USD 4.16/gallon gasoline — the EIA weekly average for September 2026 — costs 300 ÷ 28 × USD 4.16 = USD 44.57 one-way. Round trip: USD 89.14. The math is universal across regions — only the units differ. The US uses miles + US gallons; UK uses miles + UK gallons (1.20 US gal); EU + Asia uses kilometers + litres or L/100km. The conversion math: 1 mile = 1.609344 km exactly and 1 US gallon = 3.785412 L (NIST Special Publication 811, Appendix B.9), which is where the 235.215 constant comes from — 100 × 3.785412 ÷ 1.609344 — so L/100km = 235.215 ÷ MPG (US), and the other way round.
The single most useful number for cross-vehicle comparison is MPG (US) — every US car is rated by the EPA on a standardised testing cycle (city, highway, combined). EPA's Automotive Trends Report (2025 edition) puts real-world fuel economy for model-year 2024 new vehicles at a record 27.2 mpg, up 41% on model year 2004; without battery-electric and plug-in hybrid vehicles the figure is 1.7 mpg lower. Pure EVs are rated in MPGe (miles per gallon equivalent): model-year-2024 EVs ranged from 53 to 140 MPGe, or 1.49 to 4.17 miles per kWh (US DOE Fact of the Week #1373).
Gas Prices Across US Markets
US pump prices vary by state with taxes, blending rules and refinery access. The federal excise is 18.4 cents per gallon and has not changed since 1993 (Federal Highway Administration); the average state gasoline tax was 33.27 cents per gallon in January 2026, before county and local levies (EIA). EIA's weekly retail survey gives national and regional averages — USD 4.157/gal for regular in the week of 7 September 2026, up from USD 3.192 a year earlier — and AAA and GasBuddy publish state and station-level prices. For multi-state road trips, where you fill up matters; price apps show live prices along a route.
European pump prices are far higher per litre than US prices because excise duty and VAT make up a large share of the price; the European Commission's Weekly Oil Bulletin tracks them by member state. High European fuel prices are the structural reason European drivers adopted high-efficiency diesel and hybrid vehicles earlier than US drivers — the marginal economics tilt sharply toward fuel-efficient options when fuel costs 2-3× more.
"A 540-mile round trip (LA to Las Vegas) at 28 MPG and USD 4.16/gal costs USD 80. The same trip in an EV at 30 kWh/100 mi and USD 0.18/kWh costs about USD 29 — a 64% saving on energy alone, before any difference in servicing."
The EV vs Gas Total-Cost-of-Ownership Math
On energy alone, at September 2026 US averages: an EV at 30 kWh/100 mi and USD 0.18/kWh costs about USD 0.054 per mile, against USD 0.148 per mile for a 28-mpg car at USD 4.157/gal (EIA) — a 64% saving. Consumer Reports' 2020 ownership-cost analysis (Harto C, Electric Vehicle Ownership Costs) found the popular EVs then priced under USD 50,000 cost USD 6,000–10,000 less over their lifetime than the best-selling gasoline vehicles in their class, with roughly half the maintenance and repair cost. Whether that holds for you turns on purchase price, incentives, your annual mileage and whether you can charge at home — the more miles and the more home charging, the further the balance tilts to the EV.
A federal tax unchanged since 1993, and the 235.215 conversion
Fuel cost formula: distance × (fuel price ÷ fuel economy). Universal across regions.
EPA's Automotive Trends Report (2025): model-year 2024 new vehicles averaged a record 27.2 mpg real-world, up 41% on model year 2004.
Federal gas tax: 18.4 ¢/gal, unchanged since 1993 (FHWA). Average state gasoline tax: 33.27 ¢/gal in January 2026, before county and local levies (EIA).
Cold costs fuel: a conventional car's city mileage is about 15% lower at 20°F than at 77°F, and up to 24% lower on 3–4 mile trips (fueleconomy.gov).
Roof-top cargo box: 2–8% worse fuel economy in the city, 6–17% on the highway, 10–25% at 65–75 mph (ORNL test, Thomas et al. 2014, via fueleconomy.gov). A rear-mount tray costs 1–5%.
Energy per mile at Sep 2026 US averages: about USD 0.054 for an EV at 30 kWh/100 mi and 18 ¢/kWh (EIA), versus USD 0.148 for a 28-mpg car at USD 4.157/gal (EIA).
Consumer Reports (2020): popular EVs under USD 50,000 cost USD 6,000–10,000 less to own over their lifetime than the best-selling gasoline cars in their class.
Aggressive driving lowers fuel economy 15–30% at highway speeds and 10–40% in stop-and-go traffic (fueleconomy.gov).
MPG conversion: 235.215 ÷ MPG (US) = L/100km, from 1 mi = 1.609344 km and 1 US gal = 3.785412 L (NIST SP 811). So 28 MPG = 8.4 L/100km.
Extra weight: each additional 100 lb costs about 1% in fuel economy for a typical vehicle (fueleconomy.gov, citing Ricardo Inc.).
Frequently Asked Questions
- Distance × (fuel price ÷ fuel economy). For 300 miles at 28 MPG on USD 4.16/gal: 300 ÷ 28 = 10.7 gallons; 10.7 × USD 4.16 = USD 45 one-way. For L/100km vehicles, convert first: 235.215 ÷ L/100km = equivalent MPG. The tool handles all unit conversions automatically.
- 1 UK (imperial) gallon = 4.54609 litres exactly, against 3.785412 litres for a US gallon (NIST SP 811) — so 1 UK gallon = 1.20095 US gallons. A UK car rated at 40 MPG (UK) is 33.3 MPG (US); the numbers look similar but use different gallon definitions. The tool's "MPG (UK)" option handles this conversion automatically. UK official figures are quoted in imperial mpg alongside L/100km.
- Inversely. L/100km measures consumption (lower is better); MPG measures distance per fuel (higher is better). Conversion: 235.215 ÷ L/100km = MPG (US). So 8 L/100km = 29.4 MPG. For example, 5–8 L/100km is 29–47 MPG (US), and 12–15 L/100km is 16–20 MPG. The two scales run in opposite directions but describe the same physics.
- EIA publishes a weekly retail survey with national and regional averages (USD 4.157/gal for regular in the week of 7 September 2026); AAA publishes state-level averages daily; GasBuddy and Google Maps show user-reported prices at individual stations along a route. For an accurate trip estimate, use the price at the stations you actually plan to use — warehouse-club and unbranded stations are usually below the state average.
- Yes. fueleconomy.gov puts the weight penalty at about 1% per extra 100 lb for a typical vehicle, so four passengers and luggage — several hundred pounds — cost a few percent. Drag is the bigger factor: in Oak Ridge National Laboratory testing (Thomas et al., 2014) a large roof-top cargo box cut fuel economy 2–8% in city driving, 6–17% on the highway and 10–25% at 65–75 mph, while a rear-mount cargo tray cost only 1–5%. For a loaded highway trip with a roof box, those figures imply planning on 10–20% below your rated highway mpg; without one, a few percent.
- Reasonably accurate for a mid-size EV charging at home. The tool uses 30 kWh per 100 miles — 3.3 mi/kWh, mid-range of the 1.49–4.17 mi/kWh spread across model-year-2024 EVs (US DOE Fact of the Week #1373) — and USD 0.18/kWh, the rounded US residential average of 18.34 ¢/kWh for June 2026 (EIA Electric Power Monthly). Real consumption rises at highway speed and in cold weather (fueleconomy.gov reports EV efficiency roughly 39% lower in mixed driving at 20°F), and public fast charging is priced well above a home tariff — check the network's posted rate. For a figure specific to your car, use its EPA kWh/100 mi rating and your own electricity rate.
- Significantly. fueleconomy.gov puts the cost of aggressive driving (speeding, rapid acceleration and hard braking) at roughly 15–30% of fuel economy at highway speeds and 10–40% in stop-and-go traffic, and says each 5 mph over 50 mph is like paying about USD 0.29 more per gallon. In city driving a conventional car's mileage is about 15% lower at 20°F (−7°C) than at 77°F, and up to 24% lower on short 3–4 mile trips. Smoothing out acceleration is the cheapest improvement available to most drivers.
- Hybrids (Toyota Prius, Hyundai Sonata Hybrid) are rated as a single combined MPG number reflecting the integrated gas-electric powertrain. Plug-in hybrids (Toyota Prius Prime, Hyundai Tucson PHEV) carry two EPA ratings: a "hybrid" MPG for gas-only operation and an MPGe for electric-only mode. For trip planning, use the hybrid MPG number for long road trips (where battery is depleted) and the MPGe for daily commutes (often fully electric). The fuel cost math is the same; the EV-comparison-cost row in this tool is most informative for plug-in or full-EV drivers.
- US gas is structurally cheap by rich-country standards — USD 4.157/gal average for regular in the week of 7 September 2026 (EIA) — because of low fuel taxes and domestic refining capacity. Singapore: SGD 2.80-3.20/L (USD 7.85-9/gal equivalent) due to high taxation. Malaysia: RON95 is MYR 1.99/L for Malaysians under the BUDI95 targeted subsidy, capped at 300 litres a month; past that quota, and for everyone outside the scheme, it is the unsubsidised float — about MYR 4.37/L as at 17-23 September 2026. Indonesia: Pertalite RON90 at IDR 10,000/L, Pertamax RON92 at IDR 12,500/L, both administered rather than floating. Philippines: PHP 60-70/L. (US-dollar equivalents move with the exchange rate, so we give the local price, which is the one actually set: at roughly MYR 4.07 and IDR 17,700 to the dollar in September 2026, that is about USD 0.49/L subsidised Malaysian and USD 0.56/L Indonesian.) The pattern: US subsidises gas via low taxes; SG/EU heavily tax it; MY/ID/VN subsidise the consumer end via state-owned oil companies.
- US gas is structurally cheaper than Singapore + Philippines but more expensive than Malaysia + Indonesia (subsidised). Major US road-trip distances are also much longer — LA to Las Vegas is 270 miles each way (430 km), more than most ASEAN inter-city drives. Use the tool's per-person split feature for group road trips. EV-vs-gas economics vary by state with the local electricity tariff and gasoline price — EIA publishes both by state — and with state EV incentives. Expect far higher annual mileage than in Singapore or Manila: US commutes and weekend drives are long.
Method & sources
How it computes
Trip fuel cost = distance ÷ fuel economy × fuel price, after normalising distance to miles (1 mi = 1.609344 km), economy to US mpg (imperial mpg × 0.832674; L/100km via 235.214 ÷ value) and price to USD per US gallon (× 3.785 for a per-litre price). The EV comparison multiplies distance by a 30 kWh per 100 mile reference consumption and USD 0.18 per kWh, the rounded US residential average.
What this tool implements
- Unit conversions from NIST Special Publication 811, Appendix B.9: 1 mi = 1 609.344 m (exact), 1 US gallon = 3.785 412 L, 1 UK gallon = 4.546 09 L (exact); the page script uses 1.609 and 3.785 as rounded working constants.
- L/100km ↔ US mpg via 235.214 = 100 × 3.785412 ÷ 1.609344; imperial mpg × 0.832674 (= 3.785412 ÷ 4.54609) → US mpg.
- EV reference consumption 30 kWh/100 mi (3.33 mi/kWh), mid-range of the EPA-rated 1.49–4.17 mi/kWh spread for model-year-2024 EVs (US DOE FOTW #1373).
- EV electricity reference USD 0.18/kWh = EIA Electric Power Monthly Table 5.6.A US residential average of 18.34 ¢/kWh for June 2026, rounded.
Sources
- National Institute of Standards and Technology. Special Publication 811, Guide for the Use of the International System of Units — Appendix B.9 conversion factors (mile 1.609 344 E+03 m exact; gallon (U.S.) 3.785 412 L; gallon (U.K.) 4.546 09 L exact). https://www.nist.gov/pml/special-publication-811/nist-guide-si-ap…
- U.S. Energy Information Administration. Electric Power Monthly, Table 5.6.A — Average Price of Electricity to Ultimate Customers by End-Use Sector, June 2026 (U.S. residential 18.34 cents/kWh). https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=e…
- U.S. Department of Energy / U.S. EPA, fueleconomy.gov — Driving More Efficiently: roof-top cargo box −2–8% city, −6–17% highway, −10–25% at 65–75 mph (citing Thomas J, Huff S, West B. SAE Int J Passeng Cars Mech Syst 2014;7(2):862-872); about −1% per extra 100 lb; aggressive driving −15–30% at highway speeds. https://www.fueleconomy.gov/feg/driveHabits.jsp
- U.S. Department of Energy, Vehicle Technologies Office. Fact of the Week #1373, 16 December 2024 — efficiency of model-year 2024 EVs ranged 1.49–4.17 mi/kWh (53–140 MPGe). https://www.energy.gov/node/4847495
What can make this go out of date
- US residential electricity price — EIA Electric Power Monthly Table 5.6.A, monthly (18.34 ¢/kWh in June 2026); the 18 ¢/kWh reference rounds this and should be re-read when the stamp expires.
- Fuel price — entered by the user; the prose quotes EIA's weekly US regular gasoline retail average (USD 4.157/gal, week of 7 Sep 2026) and EIA's January 2026 state-tax average (33.27 ¢/gal), both revised on EIA's schedule.
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