Tukuk-OS📏 Chicago to San Francisco
| Great-circle (haversine, R = 6371.0088 km) | 2,985.1 km |
| Miles (international) | 1,854.9 mi |
| Nautical miles | 1,611.8 nmi |
| Initial true bearing | 272.9° W |
| Flight at 900 km/h (no climb, taxi or wind) | 199 min |
| Drive at 80 km/h, non-stop | 37.3 h |
| Latitude change | -4.1100° |
| Longitude change | -34.7900° |
ℹ️ What this tool does & how it works
The air line between the two is 2,985 km (1,855 statute miles, 1,612 nautical miles). It comes from the haversine formula on the two coordinate pairs the page carries — Chicago at 41.8800° N, -87.6300° W and San Francisco at 37.7700° N, -122.4200° W — using the IUGG mean Earth radius of 6371.0088 km. Leaving Chicago toward San Francisco you start on a true bearing of 272.9° (W); because the Earth curves, that heading drifts as you go.
How the Chicago and San Francisco distance is worked out
Two points on a sphere are separated by the shorter arc of the great circle that passes through both of them, and the haversine formula is the numerically stable way to get its length: it converts the latitude difference and the longitude difference into a single chord ratio, takes its square root, and multiplies by twice the radius. Written that way it stays accurate even for pairs a few kilometres apart, which is why it is still the standard in navigation code. The radius used here is 6371.0088 km, the IUGG mean radius; on the true WGS84 ellipsoid the same Chicago–San Francisco arc differs by a few tenths of a per cent depending on the route's orientation, which is well inside the error of a city-centre coordinate.
What that number means for an actual trip
It is the distance a bird flies. A 2,985 km line becomes roughly 3,881 km of road once hills, borders, river crossings and bypasses are counted — the 1.2 to 1.4 multiplier is the usual empirical range, and this page does not pretend to know the road you would take. Air distance is closer to the figure above, though airline routings, wind and holding add time to the 199 minutes a perfect 900 km/h cruise would take. Rail sits between the two. The latitude and longitude changes in the table show why the line is not simply "north" or "east": a 4.11° shift in latitude is about 457 km, while the same number of degrees in longitude shrinks with the cosine of the latitude.
Both positions, exactly
Chicago, United States (Americas): 41° 52′ 48.0″ N, 87° 37′ 48.0″ W — decimal 41.88, -87.63, GeoHash dp3wmbjb9. San Francisco, United States (Americas): 37° 46′ 12.0″ N, 122° 25′ 12.0″ W — decimal 37.77, -122.42, GeoHash 9q8yy7b6p. Those two pairs are all this page needs, and everything above is derived from them; nothing is fetched, and the coordinates you can edit in the form are recalculated by your own browser, so a different pair costs nothing and stays on your device.