How far is Boulder, CO from Thornton, CO?
The driving distance from Boulder, CO to Thornton, CO is about 25.8 miles (41.6 km), with a travel time of about 00h 30m by car.
- The straight-line flight distance is about 18.8 miles (30.3 km).
- For a round trip, plan for roughly 01h 01m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 7:00 AM to 7:00 PM MDT.
Reverse, save, or send this route
This is an easy same-day return drive. Copy the route link, send it to another device, or print a clean version before you head out.
This is an easy same-day return drive.
Flight Distance
Driving Distance
Gas Cost Calculator
Leave and Arrive Planner
Pick a departure time to see your estimated arrival and same-day return window.
Drive time stays fixed at 00h 30m.
This is a short drive, so your comfort window is wide. Traffic and current weather matter more than the clock.
You are leaving earlier than the recommended window, which gives you extra margin for breaks and traffic.
Halfway Point
A useful midpoint for breaks, coffee, or meeting in the middle.
A city in Broomfield County, Colorado.
Route Weather Snapshot
Check the forecast at both ends before you head out.
Mostly Sunny
Sunny
Driving Route Map
The map below follows the saved road route between Boulder and Thornton.
Turn-by-Turn Driving Directions
Step-by-step road directions between Boulder and Thornton.
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1
Start on the route
27 m · 7 sec
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2
Turn right onto 19th Street
44 m · 14 sec · 19th Street
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3
Turn left onto Arapahoe Avenue
3210 ft · 2 min · Arapahoe Avenue
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4
Turn right onto 28th Street
1.2 km · 2 min · 28th Street
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5
Turn straight onto Denver–Boulder Turnpike
3.4 mi · 4 min · Denver–Boulder Turnpike
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6
Keep slight right to continue on Denver–Boulder Turnpike
1.7 mi · 2 min · Denver–Boulder Turnpike
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7
Keep slight right to continue on Denver–Boulder Turnpike
2.6 mi · 3 min · Denver–Boulder Turnpike
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8
Keep slight right to continue on Denver–Boulder Turnpike
2.4 mi · 3 min · Denver–Boulder Turnpike
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9
Keep slight right to continue on Denver–Boulder Turnpike
2.2 mi · 3 min · Denver–Boulder Turnpike
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10
Keep slight right to continue on Denver–Boulder Turnpike
1.9 mi · 2 min · Denver–Boulder Turnpike
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11
Keep slight right to continue on Denver–Boulder Turnpike
1.2 km · 53 sec · Denver–Boulder Turnpike
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12
Take the exit slight right toward CO 95 South: Sheridan Boulevard
1708 ft · 37 sec
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13
Turn sharp left onto Sheridan Boulevard
1665 ft · 40 sec · Sheridan Boulevard
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14
Turn straight
93 m · 11 sec
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15
Turn straight onto West 92nd Avenue
2.5 mi · 5 min · West 92nd Avenue
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16
Continue on Thornton Parkway
2 mi · 4 min · Thornton Parkway
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17
Turn right onto Dorothy Boulevard
1077 ft · 51 sec · Dorothy Boulevard
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18
Turn right
36 m · 9 sec
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19
Arrive at your destination
0 m · 1 sec
Car Route Details
A richer read on the saved driving route between Boulder and Thornton.
Turn-heavy local drive
The route has frequent decision points for its length, so lane choice and turn timing will matter more than cruising speed.
Denver–Boulder Turnpike
Turn straight onto Denver–Boulder Turnpike
3.35 mi · 00h 04m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A short regional drive
This route is short enough to handle as a quick errand, commute, or easy same-day return without much planning overhead.
Mostly Sunny leaving Boulder and Sunny near Thornton.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Boulder to Thornton?
The road trip is about 25.8 miles (41.6 km) and usually takes 00h 30m in normal driving conditions.
Is this a same-day trip or an overnight route?
This route is short enough to handle as a quick errand, commute, or easy same-day return without much planning overhead.
What is the halfway point on this route?
Broomfield is a useful midpoint, sitting about 10.9 miles from Boulder and 15 miles from Thornton.
How much longer is the road route than the straight-line distance?
The direct path is about 18.8 miles (30.3 km), while the road route adds roughly 7 extra miles because roads do not follow the straight air line.
When is the best time to leave for this route?
A good departure window is usually 7:00 AM to 7:00 PM MDT. If you want a more comfortable same-day return, try to leave by 7:28 PM MDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $3.37 one way or $6.73 round trip. Estimated CO2 is about 8.1 kg one way.
What should you check before leaving?
Before you leave, expect Mostly Sunny around Boulder and Sunny near Thornton.
Stop Ideas Near Broomfield
Useful break, food, and waypoint ideas within about 15 miles of the route midpoint.
Municipal Court Park
Denver City Council
Lafayette City Hall
Transit and Meeting Points
Useful pickup, handoff, or rendezvous points close to Broomfield.
Union Station
Denver (Bus Station), Colorado
Boulder, Colorado
Longmont, Colorado
Flight Path Map
This map shows the direct air route between Boulder and Thornton. Straight-line distance: 18.8 mi (30.25 km).
#1 Boulder
The most populous city in Boulder County, Colorado.
| Population | 107,645 |
| Coordinates | 40.0149900, -105.2705500 |
| Altitude | 1624 |
| Country | United States |
#2 Thornton
The seventh most populous city in Colorado.
| Population | 148,113 |
| Coordinates | 39.8680400, -104.9719200 |
| Altitude | 1631 |
| Country | United States |
End: (-104.971859, 39.868064)
Estimated Travel Time
Distance: 42 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 00h 51m |
| 40 mph (64.37 km/h) | 00h 38m |
| 50 mph (80.47 km/h) | 00h 30m |
| 60 mph (96.56 km/h) | 00h 25m |
| 70 mph (112.65 km/h) | 00h 22m |
| 80 mph (129 km/h) | 00h 19m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.70 | $3.37 | $6.73 |
| Mid-grade | $4.08 | $3.72 | $7.43 |
| Premium | $4.39 | $4.00 | $7.99 |
| Diesel | $4.74 | $4.31 | $8.62 |
Assumes 8.3 L/100 km (about 28.3 MPG). CO2 is an estimate and varies by vehicle, fuel blend, traffic, and terrain.
Prices in Colorado · Apr 23, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.