If you have an important race like a 10k or a half marathon coming up, you might be looking for a way to estimate your race time before you actually compete. There are four different methods you can use to make a prediction based on your practice times. These are the Riegel Formula, the Cameron Formula, VO2 Max, and age grading. Having an approximate idea of how fast you’ll be able to go is very useful, because it can help you set goals and focus on things you need to work on.

**Riegel Formula**

Peter Riegel created this formula in the 1970’s to help runners make predictions mathematically. It was published in Runner’s World Magazine in 1977. The formula is : T2 = T1 x (D2 ÷ D1)^{1}.06. T1 is your previous race time. D1 is the distance you ran in that race. D2 is the distance you will be running in the next race. T2 is your predicted time. All you have to do is input these numbers and you will get an approximate idea of how fast you will go. This method is useful because it requires no conversion of units.

**Cameron Formula**

This formula is a little bit more complicated than the last formula. It was originally created to use with world and US national race records. The formula is as follows:

```
a = 13.49681 - (0.000030363 x old_dist) + (835.7114 ÷ (old_dist^0.7905))
b = 13.49681 - (0.000030363 x new_dist) + (835.7114 ÷ (new_dist^0.7905))
new_time = (old_time/old_dist) x (a ÷ b) x new_dist
```

You will need to calculate a and b with the formula above, and then use those calculations to complete the formula for new time.

**VO2 Max**

A VO2 Max test can calculate how much oxygen you can consume during exercise. You can search online for places in your city that can test your VO2 Max rate, which is usually done by monitoring your running on a treadmill. The more oxygen you consume during exercise, the better, and the higher your VO2 Max, the more likely you are to be successful in your racing.

VO2 Max rates are relative to age, with younger people generally having higher VO2 Max scores. Daniels & Gilbert have a formula for calculating VO2 Max from your race times. However, if you already know your VO2 max but want to know your estimated race times, you can plug in the VO2 Max and solve for your race time.

The formula is:

```
VO2Max =
(-4.60 + 0.182258 x velocity + 0.000104 x velocity^2)
/
(0.8 + 0.1894393 x e^(-0.012778 x time) + 0.2989558 x e^(-0.1932605 x time))
```

However, this is not always the most convenient method for predicting your race times, as you must know the velocity of your running.

**Age Grading**

Age grading predictions use world record times as a base measurement, and assume that runners will always run the same times relative to these records based on their age and gender. If the runner has run a half marathon at say, 50% of the world record time, they will always run at 50% of the world record time for each race, according to this method. While this method is simple and quick to use, it is not as accurate as the others.