Is your goal time on?
Enter a recent race and the time you're chasing. You'll see the gap, the paces to train at, and how far to trust the answer. It's free and needs no account.
Want a plan built around your goal?
RacePacer turns a goal time into a training plan, then updates your predicted finish as you log your weeks. We are in private beta and invite runners in waves, so join the waitlist and we'll email you when it's your turn.
The method and its limits
This is plain arithmetic. Your race is projected to the goal distance with Riegel's race-time formula from 1981, using an exponent of 1.06, or 1.07 for a marathon. RacePacer's in-app prediction starts from the same sums.
A goal at or slower than the projection reads as within reach. Up to 3% faster reads as realistic, 3% to 8% as ambitious, and beyond that as very ambitious.
Training paces are rules of thumb. Easy is 10% to 25% slower than your projected marathon pace, threshold is what the formula says you could hold for an hour, and intervals are your projected 5K pace.
A 5K says little about a marathon. The further your race is from your goal, the weaker the answer. It assumes you are as fit today as on race day, and it takes no account of your weekly distance, the course or the weather.