About the Road Trip Cost Planner
Every other trip calculator asks for “the gas price” — one number for a drive that crosses four states with four different prices. This one routes the actual roads, assigns every mile to the state it is driven in (US Census boundaries, checked every two kilometres and bisected to a tenth of one at each state line), and prices each state’s share at that state’s current AAA average, refreshed hourly. Cross from Indiana into Illinois and the cost moves the way your receipts would.
Your car is your car: pick the exact trim and the planner uses the EPA’s own combined MPG (or MPGe, converted to kWh per 100 miles for an EV), or type the real figure you get on the highway. Electric trips are priced at each state’s EIA residential rate or a public fast-charging price you set — because those differ by two to three times, and pretending otherwise is how EV road-trip estimates go wrong. Nothing you enter is stored; routes are cached anonymously for a week.
Where to buy fuel so that the expensive states are crossed on gas bought in the cheap ones. Assumes you can fill anywhere in a state at that state’s average, and never lets the tank run dry.
How many fast-charging stops the trip needs and how long they take, using the standard 10–80% session (chargers slow down above 80%) and a 10% arrival buffer.
How to Use the Road Trip Cost Planner
Type a start and a destination (city and state is plenty), pick your car from the EPA list or type the MPG you actually get, choose one-way or round trip, and price it. The result is the trip’s real driving distance and time, the fuel it will take, and a state-by-state table showing how many miles fall in each state, that state’s price today, and what those miles cost. The strip above the table is the route in proportion — a long Indiana bar next to a short Illinois one tells you at a glance where the money goes.
Why the State Line Is the Whole Game
Gasoline taxes and blend rules are set by state, so the price does not drift across a border, it jumps. Illinois, California, Pennsylvania and Washington carry the heaviest state fuel taxes; Mississippi, Missouri, Oklahoma, Texas and Arizona are routinely among the cheapest. The practical consequence for a driver is simple and usually ignored: on an interstate that runs from a cheap state into an expensive one, the fill-up right before the line is the best-priced fuel of the trip, and a full tank there can carry you most of the way across the expensive stretch. The planner’s per-state split is what makes that decision visible; the subscriber fill-up plan turns it into gallons.
Reading the Per-State Table Honestly
Two caveats keep the numbers honest. First, the price is the state average — a reliable guide to the level, not the pump you will use. Stations right on an interstate exit charge more than the town three miles off it, and the gap can exceed the difference between neighbouring states. Second, MPG is the EPA combined figure unless you type your own, and highway cruising above 70 mph, a roof box, or mountain grades pull real consumption 10–20% above it. The estimate is the centre of a range; a 500-mile day will land within a tank’s worth of it, not to the dollar.
EV Road Trips: The Number That Matters Is Who Owns the Plug
An EV costs pennies per mile at home and something close to gasoline on a fast charger. Residential electricity in most states runs 12–22 cents per kWh (Hawaii is the outlier above 40); DC fast charging on the major networks runs 40–60 cents, sometimes with an idle fee on top. At 30 kWh per 100 miles, that is roughly 4–7 cents a mile at home versus 12–18 cents on the road — the same territory as a 30-mpg gas car at today’s prices. So the planner asks where you will charge and prices it accordingly, rather than quoting the home rate and calling the trip nearly free. The subscriber comparison runs both drivetrains over the identical route and reports the electricity price at which they break even.
Charging Stops, Done the Way the Chargers Behave
Fast chargers deliver their rated power only in the middle of the battery; above about 80% the rate tapers hard, which is why experienced EV drivers charge from 10–80% and leave. The stop planner models exactly that: each stop adds 70% of range, sessions are timed at 80% of the charger’s rated power to reflect the taper, and a 10% buffer is kept for arrival. On a 250-mile-range car that makes a 600-mile day roughly two stops of half an hour each on a 150 kW charger — and nearly an hour each on a 50 kW one, which is the number worth knowing before you plan the route around a slow station.
What This Tool Does Not Pretend to Know
Tolls (the East Coast can add $30–60 to a long day), the price at your specific exit, traffic, and weather. Drive time is the routing engine’s free-flow estimate; add stops and congestion yourself. Routes are limited to the 50 states and DC on the connected road network — the planner will tell you plainly that Honolulu and Los Angeles cannot be driven between rather than inventing a number for the water.
Related tools: the Fuel Cost Calculator for a quick flat-price estimate, the True Cost of Ownership Calculator for the same EPA data over five years, the EV vs Gas Cost Calculator for the annual version of the drivetrain question, and the live gas price trackers. Browse every Auto & Vehicle tool for more.
Routes and drive times from OSRM on OpenStreetMap data; per-state miles from US Census cartographic boundaries sampled every 2 km; gas prices are AAA state averages from the EvvyTools hourly snapshot, with the EIA weekly U.S. average as the fallback; electricity is the EIA monthly residential price by state; MPG and MPGe from the EPA’s fueleconomy.gov. Estimates, not quotes — your pump and your right foot decide the last few percent.
Frequently Asked Questions
Why price fuel state by state instead of using one number?
Because the spread between neighbouring states is routinely 50 cents to a dollar a gallon, and a route crosses several. On the day this tool shipped, Columbus to Chicago ran 239 miles through Indiana at about $3.48 and finished in Illinois at about $4.42 — a flat national average would have mispriced both. The planner assigns every mile of the actual route to the state it is in and applies that state's current AAA average, so the answer moves when you cross a line, the way your receipts do.
Where does the route and the mileage come from?
From OSRM, an open routing engine on OpenStreetMap roads — the same road network behind most free map apps. The planner takes the full route geometry, walks it in two-kilometre steps, and checks each step against the US Census state boundaries, bisecting the state line to about a tenth of a kilometre. Per-state mileage is therefore accurate to well under a mile at each crossing. Miles are then scaled so the states add up exactly to the route's driving distance.
How accurate is the fuel estimate?
The EPA combined figure is the honest anchor, but it is a lab number: real highway driving at 75 mph, a loaded roof box, mountain passes or a headwind can cost 10–20% more. Treat the estimate as the centre of a range and, if you know your car's real trip MPG, type it in instead — the planner accepts either. Prices are today's state averages, not the pump you will actually stop at, so budget a few percent either way on a long trip.
How is EV charging priced?
Two ways, and the difference matters. "Home rate" uses each state's EIA residential electricity price — the right number if you charge overnight at your destination or at friends' houses. "Public fast charging" uses a per-kWh price you set, defaulting to 48 cents, because DC fast charging on a road trip typically costs two to three times the home rate. Energy use is the EPA kWh per 100 miles for your trim (converted from MPGe at 33.7 kWh per gallon-equivalent), and, like MPG, real highway use at speed and in cold weather runs higher.
Can it handle a multi-stop trip or a loop?
Yes. Round trip doubles each state's mileage (not just the total, so the state prices still apply correctly). Subscribers can add up to five intermediate stops, and the planner routes them in order, prices each leg, and reports per-leg distance and drive time. Stops must be in the 50 states or DC on the connected road network — Hawaii and the mainland, for instance, cannot be driven between and the planner says so instead of guessing.
