A car travels 120 miles at an average speed of 40 mph, then continues for another 180 miles at 60 mph. What is the car’s average speed for the entire trip?

February 22, 2026

Title: How to Calculate Average Speed for a Two-Part Road Trip | Fast and Efficient Travel

When planning road trips, determining average speed is essential for better time management and trip planning. One common scenario involves multiple segments with varying speeds—like a car traveling 120 miles at 40 mph, then continuing another 180 miles at 60 mph. Understanding the total journey and total time helps calculate the overall average speed accurately. In this article, we’ll break down how to compute the average speed for the entire trip, why it’s more than just a simple mean, and how to find the correct figure for smoother travel forecasts.

What Is Average Speed?

Average speed is defined as the total distance traveled divided by the total time taken, not the arithmetic mean of speeds. This matters because speed changes across different segments—longer periods at lower speeds drag down the overall average, even if a segment was completed quickly.

The Journey Breakdown

In this example:

First leg: 120 miles at 40 mph
Second leg: 180 miles at 60 mph

Step 1: Calculate Time for Each Segment

Segment 1: Time = Distance ÷ Speed Time₁ = 120 miles ÷ 40 mph = 3 hours

Segment 2: Time₂ = 180 miles ÷ 60 mph = 3 hours

Step 2: Total Distance and Total Time

Total distance: 120 + 180 = 300 miles
Total time: 3 + 3 = 6 hours

Step 3: Calculate Average Speed

Average speed = Total distance ÷ Total time Average speed = 300 miles ÷ 6 hours = 50 mph

Why This Method Works

Assuming the first leg took 3 hours at 40 mph correctly accounts for the slower pace. The faster second segment reduces total time but doesn’t overshadow the impact of the slower portion. This weighted average ensures realistic planning.

Final Takeaway

For a trip covering 120 miles at 40 mph followed by 180 miles at 60 mph, the overall average speed is 50 mph, not 50 mph as the arithmetic mean of 40 and 60 (which is 50). But be cautious—only use the total time divided by total distance for accuracy, not averaging the speeds directly.

Use precise time calculations to create better itineraries, estimate arrival times, and improve travel efficiency.

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