Reverse VDOT Calculator

A VDOT of 50 is a 19:56 5K, a 41:20 10K, a 1:31:31 half and a 3:10:40 marathon. Type any score from 30 to 85 above and the calculator returns the race time it predicts at every distance from 1500 m to the marathon, plus the easy and threshold pace bands that go with it. The VDOT calculator runs the other way, race time in and score out; this page starts from the score.

VDOT to race time

Find your score on the left. Every time in the row is what the same aerobic fitness predicts at that distance, computed from the Daniels and Gilbert equations that produce the published Daniels tables. The full table further down runs in steps of two from VDOT 30 to 80 and adds the mile.

Five points of VDOT is worth about two minutes over 5K in the middle of the table and close to eighteen minutes over the marathon. That ratio is the whole argument for training the short distances hard even when the goal race is long.

What the reverse direction is for

The forward calculator answers "how fit am I". This one answers three different questions. The first is goal setting: you want to break 3:00 in the marathon, and you need to know what that fitness looks like at 5K on a Tuesday night, because a 5K is a race you can run next month and a marathon is not. The equations put sub 3 at about VDOT 53.5, which is a 5K around 18:50. If you cannot run that, you do not own the marathon yet.

The second is reading a plan. Daniels writes his sessions as VDOT paces, and a lot of other programs borrow the habit, so a plan that says "run at VDOT 48 threshold" needs converting into a number the watch can hold. Type 48 and the threshold band appears.

The third is checking a target someone else gave you. A coach says you are a 52. This table tells you what a 52 runs.

How the equations work

Two curves do the job, the same two that run the forward calculator in reverse. One gives the oxygen cost of running at a speed. The other gives the fraction of your maximum you can hold for a given duration, which falls as races get longer, because nobody holds 100 percent of VO2max for two hours. For a target distance the calculator searches for the time where the oxygen cost of that speed, divided by the sustainable fraction at that duration, equals your VDOT. It does that once per distance, so each time in the row is solved independently rather than scaled from the 5K.

The easy and threshold paces come from the same velocity. Easy is 59 to 74 percent of the speed at VDOT, threshold 83 to 88 percent. The VDOT calculator page lists all five bands and what each session is for.

It is an equivalence, not a promise

Every time in the row assumes a runner trained for that distance. The equations describe an equally fit athlete who has done the long runs, practised the fuelling and paced the race well. They say nothing about whether you have. A 5K runner at VDOT 50 does not run 3:10:40 in the marathon on 5K training; most fall 10 to 20 minutes short of the row until the long runs are in place, and the gap is endurance, not a fault in the maths.

The reverse holds too. A marathoner at VDOT 50 who has not touched a track for a year will not run 19:56 next week. The speed is in there. It needs waking up.

Two more limits. The equations were fitted to performances on flat courses in cool conditions, so the marathon row in particular assumes weather that most spring and autumn marathons deliver and most summer ones do not. And the scale gets rough below 30, where the sustainable-fraction curve was fitted to few data points, which is why the calculator stops there.

Choosing the right score to type

If you are converting a race, get the score from the VDOT calculator first, using a race from the last four to six weeks on a measured course. A half marathon gives the most honest marathon prediction. A 5K gives the most honest read on current speed. The mile is the least reliable input for anything longer than 10K.

If you are setting a goal, pick the row for the race time you want and read across to the 5K. That number is your test. Run it in a low-key race or a time trial six to eight weeks out, and if you hit it, the goal is real.

How Movement Rebels fits

A VDOT row is a target. Your training data is the test. Connect Garmin Connect or Apple Health and the coach in Movement Rebels reads each run as it lands, pace, cadence and per-kilometre splits included, so a threshold session prescribed at 4:15 to 4:28 per km gets checked rep by rep against what the watch recorded.

The coach plans the block in your calendar, threshold days and intervals and the easy volume between them, and when auto push is on the planned sessions land on your Garmin watch as structured workouts with the paces from this table loaded before you leave the house. It cannot make you a VDOT 50. It can tell you, after every session, if you are training like one. The week that gets you there is laid out in 5K and 10K Training.

Related calculators

The VDOT calculator goes the other way, from a race result to a score. The race time predictor converts one race to another with Riegel's formula, and race predictor formulas shows how that compares with the VDOT equivalence above. For the pace the target time needs at every marker, use the pace band calculator or the marathon pace chart. To see what a time is worth for your age, the reverse age grade calculator gives the time a target percentage needs and the age grade calculator grades a time you have run.

VDOT score to race time

Computed from the Daniels-Gilbert equations, which reproduce the published Daniels tables within a few seconds.

Open-class standards used for age grading

Your age-grade percentage is the standard divided by your time and your age factor. 100 percent means you matched the open-class world standard for the distance after the age adjustment.

Questions

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