SRT Files: What They Are & How Video Subtitles Work

SRT files are plain-text subtitle files that contain timed captions for video content. You load an .srt file alongside a video file in a media player or video editor, and the player displays each subtitle at the time specified in the file. This format is one of the most widely supported subtitle standards, working across VLC, YouTube, Premiere Pro, and most other video software.

Formula

The calculator works out your average running pace and speed from a finish time and distance. The formula is:

Pace (min/km) = Finish time (minutes) ÷ Distance (km)

Speed (km/h) = Distance (km) ÷ (Finish time (minutes) ÷ 60)

Where:

• Finish time – total time taken, in minutes (e.g., 50 minutes).
• Distance – distance covered, in kilometers (e.g., 10 km).
• Pace – time per kilometer, shown in minutes and seconds (e.g., 5:00 min/km).
• Speed – average speed, in kilometers per hour (e.g., 12.0 km/h).

Worked Example

Using the default values – finish time 50 minutes, distance 10 km:

1. Pace = 50 ÷ 10 = 5.00 min/km (shown as 5:00).
2. Speed = 10 ÷ (50 ÷ 60) = 10 ÷ 0.8333 = 12.00 km/h.

So a 50-minute 10K corresponds to a 5:00 min/km pace and an average speed of 12.0 km/h.

When to Use This Calculator

Use this tool when you have a race or training run finish time and want to know your average pace or speed. It helps you set realistic goals, compare performances across different distances, or plan training paces. For example, if you ran a half marathon (21.1 km) in 1 hour 45 minutes (105 minutes), the calculator gives you a pace of 4:59 min/km – useful for predicting a marathon time or setting interval training targets.

How to Read the Results

The first output (pace) is shown as minutes per kilometer, formatted as MM:SS. A lower pace means faster running. The second output (speed) is your average speed in km/h – higher is faster. These two values are inversely related: a 5:00 min/km pace equals 12.0 km/h, while a 4:30 pace equals 13.3 km/h. For imperial users, you can convert km to miles (1 km = 0.621371 miles) to get pace per mile.

Common Mistakes

• Unit mix-ups: Entering distance in miles but expecting km/h results. Always convert to the same unit system.
• Time in hours: If you enter hours as a decimal (e.g., 1.5 for 1:30), the calculator treats it as minutes. Use minutes only.
• Rounding too early: Rounding pace to whole minutes can hide important differences; keep at least one decimal or use the MM:SS format.

Limitations of the Formula

This calculation assumes a constant pace throughout the run. In reality, terrain, elevation, and fatigue cause pace to vary. The result is an average, not a prediction of your ability to hold that pace. Also, the formula ignores rest stops or pauses – it uses total time from start to finish. For interval training or hilly routes, a GPS watch or running app may give more accurate per-segment data.

Frequently Asked Questions

How do I convert pace from min/km to min/mile?
Multiply the pace in min/km by 1.60934. For example, 5:00 min/km becomes 8:03 min/mile. Or use the speed value: 12 km/h ÷ 1.60934 = 7.46 mph.

What is a good running pace for a beginner?
It varies widely, but a common starting pace for a 5K is around 7:00–8:00 min/km (11–13 min/mile). Focus on effort rather than a specific number.

Can I use this for walking or cycling?
Yes, the formula works for any activity where you measure time and distance. Just enter your total time and distance.

Why does the speed output show km/h but I want mph?
The calculator uses km by default. To get mph, convert your distance to miles first (divide km by 1.60934) before entering it.

How do I calculate my pace for a marathon?
Enter the marathon distance (42.195 km) and your target finish time in minutes. The calculator gives you the required average pace per km.

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in t | Finish time | min | 50 | 0
in d | Distance | km | 10 | 0
out pace | Average pace | min/km | t / d | 2
out speed | Average speed | km/h | d / (t / 60) | 2