Colorado

Distance from Boulder to Thornton

Straight-line distance

17.9mi

Boulder, CO and Thornton, CO are 17.9 miles (28.8 km) apart in a straight line. From Boulder, the shortest path starts out heading ESE (114°).

kilometers
28.8
nautical miles
15.6
heading from Boulder
114° ESE
heading from Thornton
294° WNW
BoulderThornton

Orange line: great-circle path · ring: midpoint · thin lines: county borders

How far Boulder is from Thornton

The great-circle distance between the Census internal points of Boulder and Thornton is 17.9 miles, 28.8 km or 15.6 nautical miles. That is the shortest path over the Earth's surface, computed with the haversine formula on a sphere with the mean Earth radius, 6,371.0 km. A course held on one compass bearing (a rhumb line) would be 17.9 miles, practically the same at this range.

Measurements

Miles
17.9
Kilometers
28.8
Nautical miles
15.6
Bearing from Boulder
113.5° ESE
Bearing arriving at Thornton
113.7°
Bearing from Thornton
293.7° WNW

Halfway between Boulder and Thornton

The great-circle midpoint is at 39.972503, -105.096232 (39°58'21.01"N 105°05'46.44"W). The nearest incorporated place of 1,000 or more people is Lafayette, CO, with 30,587 residents, 1.6 miles from the midpoint. To find towns near the midpoint of any two places, use the halfway tool.

Time zones and daylight

Both use America/Denver, so there is no time difference. On June 21, Boulder gets 15 h 01 min of daylight and Thornton 15 h 00 min; on December 21, 9 h 20 min and 9 h 20 min. The two sit at nearly the same latitude, so their day lengths match closely all year.

Population compared

Thornton has 1.4 times the population of Boulder. From July 2020 to July 2024, Boulder changed by -1.5% and Thornton by +3.2%. Both are in Colorado.

  1. 01Boulder, CO106,803 (-1.5%)
  2. 02Thornton, CO146,689 (+3.2%)
July 1, 2024 population and change since July 2020, Census Vintage 2024.

Questions people ask

How far is Boulder from Thornton?

17.9 miles, 28.8 km or 15.6 nautical miles along the great circle between the two Census internal points. Road distance is longer.

Which direction is Thornton from Boulder?

ESE. The great-circle path leaves Boulder on a bearing of 113.5° and arrives at Thornton on 113.7°. The return trip starts on 293.7°.

What is halfway between Boulder and Thornton?

The midpoint is at 39.972503, -105.096232. The nearest incorporated place of 1,000+ is Lafayette, CO, 1.6 miles from it.

Is there a time difference between Boulder and Thornton?

Both use America/Denver, so there is no time difference.

Which is bigger, Boulder or Thornton?

Thornton, with 146,689 residents in July 2024 against 106,803 for Boulder, 1.4 times as many.

Sources and data as of

Data as of: Census 2024 Gazetteer internal points and Vintage 2024 estimates; time zones from Open-Meteo.

  1. 01Census 2024 Gazetteer, places
  2. 02Census Vintage 2024 subcounty population estimates
  3. 03SunCalc library (Vladimir Agafonkin), algorithms after Jean Meeus
  4. 04IANA time zone database (clock times and daylight saving rules)

How every number is computed: methodology. Spotted a wrong figure? Report an error.