About Distances Online, and how these numbers are worked out
Distances Online answers one question: how far is it from one US city to another, and what does that mean in hours behind the wheel and dollars of fuel. Every route also shows the towns you would pass, the time-zone change if there is one, and how driving compares with flying.
It is free, needs no account, and carries no advertising and no tracking.
How the distances are estimated
Each figure starts from the great-circle distance — the shortest line between two points on the globe — multiplied by a road factor, which accounts for how much longer a real road network runs than that straight line.
The factor is not constant. Short trips are proportionally more indirect, because street grids and rivers force detours; long trips spend most of their miles on interstates and come much closer to the direct line. It runs from about 1.36 on trips under 15 miles down to about 1.16 on long ones.
A factor alone cannot see geography, so a second step handles water. Where the straight line crosses a lake, a bay or a sound, the route is rebuilt through the crossings and shore roads the highway network actually uses — round the foot of Lake Michigan, over the Chesapeake Bay Bridge, past the west end of Lake Erie. Without that step a drive from Milwaukee to Grand Rapids came out at 139 miles instead of 280.
How close does it get? Close enough for planning, and not more than that. The figure is derived rather than measured against the road, so treat it as approximate — the shorter the trip, the larger the proportional gap. For a delivery quote or a legal mileage claim, use a routed figure instead.
Fuel, time and CO₂ assumptions
- Fuel price
- $3.15 / gallon
- Fuel economy
- 25.4 mpg
- CO₂ per gallon burned
- 8.89 kg
- Cruise speed, flying
- 500 mph
- Airport and ground time
- 2.5 hr
- CO₂ per passenger mile, flying
- 0.24 kg
These are fixed assumptions, reviewed periodically — last checked 2026-08. They are not a live price feed, so a fuel cost here is a ballpark, not a quote. Driving CO₂ counts the vehicle; flying CO₂ is per passenger, which is why a full car compares well against a seat on a plane.
Data sources
- City names, locations and populations — derived from the GeoNames gazetteer via the all-the-cities dataset (MIT license), which draws on GeoNames. Just over 16,000 US places above roughly 1,000 residents.
- Time zones — resolved from coordinates with the tz-lookup dataset (CC0, published on npm; its original repository is no longer online), then applied with the browser's own IANA time-zone rules so daylight saving is handled correctly.
- The map — state boundaries from us-atlas (ISC license), built from US Census Bureau cartographic files, drawn here as an Albers equal-area projection of the contiguous states. It is a locator map, not a road map.
Corrections and contact
If a distance here looks wrong, a city is missing or a page is broken, the useful thing to send is the URL and what you expected instead — that is enough to check it against the dataset. Mail [email protected]. There is no form, no newsletter and nothing to sign up for; the address is the whole of it.
Two kinds of correction are worth separating. A missing or misplaced city is a data problem and can be fixed. A distance that disagrees with a mapping service usually is not a mistake: the figures here are estimates built from a great-circle distance and a road-detour factor, not routed directions, and the difference between the two is explained above under how the distances are estimated. Both are worth writing about, but the second will get an explanation rather than a change.