How far is Longmont, CO from Castlewood, CO?
The driving distance from Longmont, CO to Castlewood, CO is about 51.1 miles (82.3 km), with a travel time of about 01h 06m by car.
- The straight-line flight distance is about 41.6 miles (67 km).
- For a round trip, plan for roughly 02h 12m 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 06m.
A morning start gives you useful time at the destination and keeps the return out of the late evening.
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.
City in Colorado
Route Weather Snapshot
Check the forecast at both ends before you head out.
Rain And Snow
Rain And Snow Showers
Driving Route Map
The map below follows the saved road route between Longmont and Castlewood.
Turn-by-Turn Driving Directions
Step-by-step road directions between Longmont and Castlewood.
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1
Start on the route
19 m · 7 sec
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2
Turn right onto 5th Avenue
1025 ft · 47 sec · 5th Avenue
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3
Turn right onto Collyer Street
1255 ft · 42 sec · Collyer Street
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4
Turn left onto 3rd Avenue
1.8 mi · 3 min · 3rd Avenue
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5
Turn left onto East Ken Pratt Boulevard
1.6 mi · 2 min · East Ken Pratt Boulevard
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6
Continue on Highway 119
3 mi · 4 min · Highway 119
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7
Take the exit right toward I 25 South
2690 ft · 1 min · West I 25 Frontage Road
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8
Merge slight left onto Dwight D. Eisenhower Highway
11.9 mi · 12 min · Dwight D. Eisenhower Highway
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9
Continue on North Valley Highway
3187 ft · 36 sec · North Valley Highway
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10
Keep slight right to continue on North Valley Highway
8.8 mi · 11 min · North Valley Highway
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11
Keep slight right to continue on North Valley Highway
20.8 mi · 27 min · North Valley Highway
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12
Take the exit slight right toward CO 88: Arapahoe Road
1289 ft · 29 sec
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13
Turn right onto East Arapahoe Road
2024 ft · 46 sec · East Arapahoe Road
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14
Turn left onto South Uinta Street
1.1 km · 2 min · South Uinta Street
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15
At the end of the road, turn right onto South Tamarac Court
593 ft · 28 sec · South Tamarac Court
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16
Turn right onto East Fremont Avenue
1294 ft · 57 sec · East Fremont Avenue
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17
Arrive at your destination
0 m · 1 sec · East Fremont Drive
Car Route Details
A richer read on the saved driving route between Longmont and Castlewood.
Highway-focused drive
Most of the mileage stays on named highways, so the important moments are ramps, exits, merges, and the final local approach.
North Valley Highway
Keep slight right to continue on North Valley Highway
20.8 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.
Rain And Snow leaving Longmont and Rain And Snow Showers near Castlewood.
Trip Questions
Direct answers travelers usually want before committing to the drive.
How long does it take to drive from Longmont to Castlewood?
The road trip is about 51.1 miles (82.3 km) and usually takes 01h 06m 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 25.6 miles from Longmont and 25.5 miles from Castlewood.
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 9.5 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 4:18 PM MDT.
How much will gas cost for this route?
Using about 28.3 MPG, regular gas is estimated at $6.66 one way or $13.31 round trip. Estimated CO2 is about 16 kg one way.
What should you check before leaving?
Before you leave, expect Rain And Snow around Longmont and Rain And Snow Showers near Castlewood.
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 Longmont and Castlewood. Straight-line distance: 41.63 mi (67 km).
#1 Longmont
The most populous city in Boulder County, Colorado.
| Population | 98,445 |
| Coordinates | 40.1672100, -105.1019300 |
| Altitude | 1519 |
| Country | United States |
#2 Castlewood
City in Hamlin County, South Dakota, United States
| Population | 25,271 |
| Coordinates | 39.5847100, -104.9010900 |
| Altitude | 1746 |
| Country | United States |
End: Castlewood (-104.90109, 39.58471)
Estimated Travel Time
Distance: 82 km by road
| Speed | Time |
|---|---|
| 30 mph (48.3 km/h) | 01h 42m |
| 40 mph (64.37 km/h) | 01h 16m |
| 50 mph (80.47 km/h) | 01h 01m |
| 60 mph (96.56 km/h) | 00h 51m |
| 70 mph (112.65 km/h) | 00h 43m |
| 80 mph (129 km/h) | 00h 38m |
Fuel, Round Trip and CO2
Estimated fuel cost and emissions for this route.
| Fuel | $/gal | One way | Round trip |
|---|---|---|---|
| Regular gas | $3.70 | $6.66 | $13.31 |
| Mid-grade | $4.08 | $7.35 | $14.70 |
| Premium | $4.39 | $7.90 | $15.81 |
| Diesel | $4.74 | $8.53 | $17.05 |
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 18, 2026
Distance to Other Cities
Planning a road trip? See the full trip guide on Trip.ovh — stops, fuel costs, weather, and departure timing.