How Long Will Your 10K Take? Method and Range

The quick method: a range from two references

The idea is simple: one reference gives you the optimistic time (the one for a day when everything goes well) and the other gives you the relaxed time (the one for running at your comfortable pace). Your first 10K usually lands between the two.

Step 1: your optimistic reference, from a 5K time

If you have run a recent, timed 5K, you can estimate your 10K with the Riegel formula: 10K time = 5K time x 2^1.06. That 2^1.06 equals 2.085 (rounded), so you only need to multiply your 5K time by 2.085.

The formula is by Peter Riegel, who published it in 1977 and expanded it in 1981 in an article on athletic records and human endurance. Its exponent is 1.06 and it applies to race durations between 3.5 and 230 minutes, a range that includes a 10K. It is a simple and widely used formula, but it only knows your time: it does not know how much you have trained to hold twice the distance or what race day will be like. To compare Riegel with VDOT and the 2.2 rule and see when not to trust it, there is predict your race time.

Step 2: your relaxed reference, from your comfortable pace

Multiply by 10 your pace per kilometer when you run comfortably, at a pace where you can talk. It is the time you would run if you held that pace for all 10 kilometers.

Step 3: the range

Your likely time falls between the two figures. It is not a fixed prediction, it is a practical way to narrow things down.

A worked example

Imagine you have just run a 5K in 32:00 and your comfortable pace is 7:15 per kilometer.

1. Optimistic reference: 32:00 is 1,920 seconds. Multiplied by 2.085 that gives about 4,003 seconds, which is 66:43. That is an average pace of 6:40 per kilometer.
2. Relaxed reference: 7:15 is 435 seconds per kilometer. Multiplied by 10 that is 4,350 seconds, which is 72:30.
3. Range: between 66:43 and 72:30.

In this example, the realistic thing is to think in terms of a window of about six minutes, instead of a specific figure. On race day, heat, the course or nerves can move you around within it.

Table: your average pace and your 10K time

If you already know what pace you run at, this table tells you how long you would take over 10 kilometers by holding it.

If your pace is not in the table, multiply your pace by 10. For example, 6:45 per kilometer is 405 seconds x 10 = 4,050 seconds, which is 67:30.

And if I want to break one hour

To run a 10K in 60 minutes your average pace would have to be 6:00 per kilometer. If you run comfortably at 7:00 today, the difference is 1 minute per kilometer, which is a lot. It is better to see that goal as a medium-term target rather than something for your first race. If you want to see a more demanding goal with all its numbers, there is 10K in 50 minutes.

If you need walking breaks

Running a 10K by alternating running and walking is a perfectly valid option. To work out the time, use your pace in each segment and add them up.

Example: you run 4 minutes at 7:30 per kilometer and walk 1 minute at 12:00 per kilometer.

1. In 4 minutes of running you cover 4 / 7.5 = 0.533 kilometers.
2. In 1 minute of walking you cover 1 / 12 = 0.083 kilometers.
3. In each 5-minute cycle you cover 0.617 kilometers.
4. For 10 kilometers you need 10 / 0.617 = 16.2 cycles, which is about 81 minutes (81:05).
5. Your average pace, counting the breaks, comes out to 8:06 per kilometer.

Count the average pace, not the pace of the running segments: it is the one that decides your final time.

Before thinking about time

If you cannot yet run 30 minutes without stopping, your 10K time is the least of your concerns. Start with the plan in run 30 minutes without stopping and then move on to the 10K training plan for beginners (in Spanish). And to spread out your running days, see how many days a week to run. If you have few weeks left before the race, prepare a 10K in a few weeks shows what is realistic from your starting point.

How to refine your estimate

• Try the 5K in conditions similar to the race, if you can.
• Check your comfortable pace with the talk test, as explained in what pace to run your easy runs at.
• Use the pace calculator and time predictor to check the formula with your data.
• If you have a time from another distance, the VDOT calculator gives you equivalent times.
• Review the estimate after a few weeks of training, because your comfortable pace may change.

What can move you within the range on race day

Even if you work out your range well, on race day there are factors that move it:

• Heat and humidity, which usually make it harder to hold your pace.
• The course: hills and tight turns change your average pace.
• The start: with a lot of people it is hard to run at your pace in the first kilometers.
• Stops at aid stations or to tie a shoe.
• How you slept and how tired you arrive.

That is why it is best to think of your time as a window and not as an exact figure.

How to set a goal for your first 10K

With the range from the example (66:43 to 72:30) you can consider three different goals:

1. Finish and enjoy it, without looking at your watch.
2. A conservative goal: finish in 72:30 or less, which is an average pace of 7:15 per kilometer.
3. An ambitious goal: get close to 66:43, which is 6:40 per kilometer.

For a first race, the most prudent choice is usually the first or the second, and leaving the third for the next one.

Common mistakes when estimating your time

• Using an old time or one from an exceptional day.
• Multiplying the pace of a short workout by 10: a 2-kilometer pace is not a 10-kilometer pace.
• Forgetting water stops, traffic lights or a start with lots of people.
• Fixing on a specific time instead of a range.
• Starting too fast on race day because you want to match the optimistic figure.