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Distance & area

Straight line vs driving distance

See the as-the-crow-flies distance and the driving distance side by side, with both lines on the map, and how much longer the road is: in miles, as a percentage and as a factor.

Example From Los Angeles to Las Vegas. Change the points to measure your own.

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Straight line

Result

In a straight line

235mi

By road

–

How much longer the road is

Tap a way to travel to see the distance and time along the route.

By road

What next?

Open these same two points in another tool.

Distance between two pointsMeasure the distance between any two places or points on the map, in miles or kilometers. Halfway pointFind the exact halfway point between two places and see it on the map, ready to share. Drive time mapSee how far you can get in a set time by car, by bike or on foot, drawn as an area on the map.

Save or share this trip

How to use it

  1. Set two points

    Search two places or addresses, paste coordinates, use your location or tap the map. You can drag A and B.

  2. Compare both distances

    The straight line shows up instantly; the driving distance follows a second later, with the route drawn in green. Switch to cycling or walking if you like.

  3. See the detour

    The tool tells you how many extra miles the route adds, what percentage that is and why it usually happens. Share the result with a link.

What it’s for

  • Mileage and quotes

    Some rates and rules use straight-line miles and others use driving miles: here you see both at once.

  • Choosing where to live

    Two towns the same distance away on the map can be very different by road. Check before you decide.

  • Hiking and trails

    Compare the distance between two points with the trail to plan the time a hike will really take.

  • Reading the landscape

    Big detours give away mountain ranges, bays and rivers with no bridge. It’s an easy way to show terrain in class.

How it’s calculated

The straight line is measured on the WGS84 ellipsoid with GeographicLib. The road distance comes from the FOSSGIS OSRM routing service on OpenStreetMap data: it’s the fastest route, the one a navigation app would pick. With both numbers, the detour takes two simple steps.

Detour factor

factor = driving distance ÷ straight-line distance

A factor of 1 would be a perfectly straight road. It can never be less than 1.

Percent longer

detour = (factor − 1) × 100%

How much the route adds to the straight line, as a share of it.

Example: Los Angeles to Las Vegas by car
Los Angeles 34.01940° N, 118.41080° W
Las Vegas 36.23350° N, 115.26400° W
As the crow flies 235 mi (378 km)
By road (OSRM, measured October 30, 2026) 291 mi (468 km) · 5 h 26 min
Extra distance 56.0 mi (90.2 km)
Detour factor 1.24
Percent longer 24%

Between Los Angeles and Las Vegas lie the San Gabriel Mountains and the Mojave Desert: the road has to go around the mountains through a pass instead of straight across, so the route is 24% longer than the straight line. The road figure changes a little with roadwork and map updates; the tool always calculates it live.

Why roads take detours

Terrain: roads climb along valleys and cross mountain ranges at the lowest passes, with curves to keep grades gentle. Water: a river with no nearby bridge, a reservoir, a bay or an arm of the sea forces you to go around. And the network itself: two small towns may have no direct road between them, so you take the interstate even if it’s out of the way.

The route is also the fastest, not the shortest: it often pays to drive a few extra miles on the freeway. In cities, street grids and one-way streets make short trips longer, so for two points less than a mile or so apart the percentage looks huge even though the difference is small.

If there’s no way to drive between the points (say, from California to Hawaii, or between continents), the tool tells you. The routing service may include a ferry leg when one exists in OpenStreetMap.

Frequently asked questions

What is straight-line distance?

The shortest distance between two points on the Earth’s surface, ignoring roads and obstacles: what people call “as the crow flies.” On the map it’s the dashed line.

How much longer is the drive from Los Angeles to Las Vegas?

235 mi (378 km) as the crow flies and 291 mi (468 km) by road, according to the route measured on October 30, 2026: 56.0 mi (90.2 km) more, or 24% longer (a factor of 1.24).

What is the detour factor?

The driving distance divided by the straight-line distance. A factor of 1.25 means the road is 25% longer. It lets you compare trips of different lengths.

Why isn’t the route the shortest one?

Because the routing service looks for the fastest route, like a navigation app: it prefers a highway even if it’s a bit longer. So the detour can come out slightly bigger than for the shortest possible road.

Can I compare cycling or walking?

Yes. Tap Cycling or Walking and the comparison uses the route for that mode, which can follow paths and streets cars can’t use.

What if there’s water in the way?

If OpenStreetMap has a car ferry, the driving route uses it and the tool points it out. If there’s no way to get there at all, it tells you there’s no road route. The straight-line distance is still correct.

Related tools

All tools
Distance between two points Measure the distance between any two places or points on the map, in miles or kilometers. Distance between cities Pick two US cities and get the distance between them, both in a straight line and by road. Distance between ZIP codes Enter two US ZIP codes to get the distance between them and see both areas on the map. Area calculator Draw around a field, a plot or any shape on the map to get its area in acres, hectares or square feet.

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