How far is Castlewood, CO from Longmont, CO?
The driving distance from Castlewood, CO to Longmont, CO is about 69.2 miles (111.3 km), with a travel time of about 01h 10m by car.
- The straight-line flight distance is about 41.6 miles (67 km).
- For a round trip, plan for roughly 02h 20m of driving time before adding stops, traffic, or weather delays.
- A comfortable departure window is usually 8:00 AM to 10:00 AM MDT.
Reverse, save, or send this route
This route works well as a day trip with time at the destination. Copy the route link, send it to another device, or print a clean version before you head out.
This route works well as a day trip with time at the destination.
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 01h 10m.
A morning start gives you useful time at the destination and keeps the return out of the late evening.
This departure sits inside the recommended comfort window for the route.
Halfway Point
A useful midpoint for breaks, coffee, or meeting in the middle.
City in Colorado
Route Weather Snapshot
Check the forecast at both ends before you head out.
Sunny then Slight Chance Showers And Thunderstorms
Mostly Sunny then Chance Showers And Thunderstorms
Driving Route Map
The map below follows the saved road route between Castlewood and Longmont.
Turn-by-Turn Driving Directions
Step-by-step road directions between Castlewood and Longmont.
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1
Start on East Fremont Drive
704 ft · 33 sec · East Fremont Drive
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2
Turn right onto East Hinsdale Avenue
151 m · 24 sec · East Hinsdale Avenue
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3
At the end of the road, turn right onto South Quebec Street
1.3 km · 2 min · South Quebec Street
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4
Turn right onto East Arapahoe Road
1.1 mi · 2 min · East Arapahoe Road
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5
Take the ramp straight toward I 25 North: Denver
859 ft · 23 sec
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6
Merge slight left onto South Valley Highway
21 mi · 27 min · South Valley Highway
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7
Keep slight right to continue on North Valley Highway
4.3 mi · 6 min · North Valley Highway
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8
Keep slight right to continue on North Valley Highway
5.3 mi · 6 min · North Valley Highway
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9
Continue on Dwight D. Eisenhower Highway
12.2 mi · 12 min · Dwight D. Eisenhower Highway
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10
Take the exit slight right toward CO 119 West: Firestone Boulevard
996 ft · 19 sec
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11
Keep slight left to continue on CO 119 West: Longmont
88 m · 8 sec
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12
Turn left onto Highway 119
3.1 mi · 4 min · Highway 119
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13
Continue on East Ken Pratt Boulevard
1.6 mi · 2 min · East Ken Pratt Boulevard
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14
Take the exit slight right
69 m · 7 sec
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15
Turn right onto East 3rd Avenue
1.9 mi · 4 min · East 3rd Avenue
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16
Turn right onto Kimbark Street
1084 ft · 55 sec · Kimbark Street
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17
Turn left
57 m · 16 sec
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18
Turn right
33 m · 8 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 Castlewood and Longmont.
Highway-focused drive
Most of the mileage stays on named highways, so the important moments are ramps, exits, merges, and the final local approach.
South Valley Highway
Merge slight left onto South Valley Highway
21 mi · 00h 27m
Route Summary
A quick read on whether this route feels easy, ambitious, or worth planning around.
A comfortable day-trip route
This route works well as a day trip. You can leave in the morning, spend meaningful time at the destination, and still return the same day.
Sunny then Slight Chance Showers And Thunderstorms leaving Castlewood and Mostly Sunny then Chance Showers And Thunderstorms near Longmont.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Castlewood to Longmont?
The road trip is about 69.2 miles (111.3 km) and usually takes 01h 10m in normal driving conditions.
Is this a same-day trip or an overnight route?
This route works well as a day trip. You can leave in the morning, spend meaningful time at the destination, and still return the same day.
What is the halfway point on this route?
Northglenn is a useful midpoint, sitting about 26.1 miles from Castlewood and 43 miles from Longmont.
How much longer is the road route than the straight-line distance?
The direct path is about 41.6 miles (67 km), while the road route adds roughly 27.6 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 8:00 AM to 10:00 AM MDT. If you want a more comfortable same-day return, try to leave by 4:10 PM MDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $9.02 one way or $18.05 round trip. Estimated CO2 is about 21.7 kg one way.
What should you check before leaving?
Before you leave, expect Sunny then Slight Chance Showers And Thunderstorms around Castlewood and Mostly Sunny then Chance Showers And Thunderstorms near Longmont.
Stop Ideas Near Northglenn
Useful break, food, and waypoint ideas within about 15 miles of the route midpoint.
Fairplay Park
Denver City Council
Lafayette City Hall
Municipal Court Park
Transit and Meeting Points
Useful pickup, handoff, or rendezvous points close to Northglenn.
Denver (Bus Station), Colorado
Union Station
Boulder, Colorado
Longmont, Colorado
Flight Path Map
This map shows the direct air route between Castlewood and Longmont. Straight-line distance: 41.63 mi (67 km).
#1 Castlewood
City in Hamlin County, South Dakota, United States
| Population | 25,271 |
| Coordinates | 39.5847100, -104.9010900 |
| Altitude | 1746 |
| Country | United States |
#2 Longmont
The most populous city in Boulder County, Colorado.
| Population | 98,445 |
| Coordinates | 40.1672100, -105.1019300 |
| Altitude | 1519 |
| Country | United States |
End: (-105.101861, 40.16721)
Estimated Travel Time
Distance: 111 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 02h 18m |
| 40 mph (64.37 km/h) | 01h 43m |
| 50 mph (80.47 km/h) | 01h 22m |
| 60 mph (96.56 km/h) | 01h 09m |
| 70 mph (112.65 km/h) | 00h 59m |
| 80 mph (129 km/h) | 00h 51m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.70 | $9.02 | $18.05 |
| Mid-grade | $4.08 | $9.96 | $19.93 |
| Premium | $4.39 | $10.71 | $21.43 |
| Diesel | $4.74 | $11.56 | $23.12 |
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 · May 30, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.