How to calculate training speeds from VIFT
Take the speed of your last completed 30-15 IFT stage, that is your VIFT, and multiply it by the zone percentage: 95 to 105 % for short intervals, 85 to 90 % for tempo, 70 to 80 % for aerobic base. For a VIFT of 18 km/h, a 15-15 at 100 % is 18 km/h, which is 75 m in 15 seconds. To get metres in 15 seconds, multiply the speed in km/h by 4.17.
The rule
VIFT is a speed in km/h. A training speed is a percentage of it.
Training speed = VIFT × zone percentage.
The zones used on this site are the ones from Buchheit’s work on the 30-15 IFT:
| Use | Zone |
|---|---|
| Active recovery | 50 to 60 % of VIFT |
| Aerobic base, continuous runs | 70 to 80 % |
| Tempo | 85 to 90 % |
| Short intervals (15-15, 10-10) | 95 to 105 % |
Step 1: find your VIFT
Your VIFT is the speed of the last stage you completed in the 30-15 IFT. It starts at 8 km/h and goes up 0.5 km/h per stage. Stage 15 is 15 km/h, stage 21 is 18 km/h, stage 25 is 20 km/h. If you do not have a result yet, run the 30-15 IFT first: do not take a VIFT from a MAS.
Step 2: apply the percentage
For a VIFT of 18 km/h:
- Recovery at 50 to 60 %: 9 to 10.8 km/h
- Aerobic base at 70 to 80 %: 12.6 to 14.4 km/h
- Tempo at 85 to 90 %: 15.3 to 16.2 km/h
- Short intervals at 95 to 105 %: 17.1 to 18.9 km/h
Step 3: turn the speed into a distance
For interval work you set cones, not a watch. A 15-second effort covers the speed in km/h times 15, divided by 3.6, which is the speed times 4.17.
| VIFT | 95 % | 100 % | 105 % |
|---|---|---|---|
| 16 km/h | 15.2 km/h, 63.3 m | 16 km/h, 66.7 m | 16.8 km/h, 70.0 m |
| 18 km/h | 17.1 km/h, 71.3 m | 18 km/h, 75.0 m | 18.9 km/h, 78.8 m |
| 20 km/h | 19.0 km/h, 79.2 m | 20 km/h, 83.3 m | 21.0 km/h, 87.5 m |
Each cell is the speed, then the distance to cover in 15 seconds. For a 10-second effort, multiply the speed by 2.78 instead. For 30 seconds, by 8.33.
An example with a squad
Three players finish stages 17, 21 and 25: VIFT 16, 18 and 20 km/h. The coach sets 15-15 intervals at 100 %. Each player runs to a cone at a different distance, 66.7, 75 and 83.3 m, for the same 15 seconds. Everyone works to the same relative intensity, but the group does not run at the same speed. That is what prescribing from VIFT is for.
What the percentages do not say
- They are a starting point. The 95 to 105 % band is wide on purpose. Adjust to the athlete and the number of repetitions.
- They assume a current VIFT. After a break or an injury, retest before prescribing.
Get the numbers without the arithmetic
The 30-15 calculator converts a stage to a VIFT and gives the speed and the distance for each zone. The difference between this scale and MAS is in VIFT vs MAS.
Go further
Frequently asked questions
How do I turn a speed in km/h into metres for a 15-second interval?
Multiply the speed by 4.17, which is 15 divided by 3.6. At 18 km/h that gives 75 m. At 16.5 km/h it gives 68.8 m.
Should I use 95 %, 100 % or 105 % of VIFT?
The range for short intervals is 95 to 105 %. Start near 95 % when the athlete is new to the session or the interval is long, and move up as it gets easy. Within one squad, using one percentage for everyone is the point of prescribing from VIFT.
Can I use a VIFT from an old test?
Only while it is still current. VIFT changes with training and after a layoff, so retest when the block changes or a player has been out. Prescribing from an outdated VIFT makes the session too easy or too hard.
Do these percentages work with MAS?
No. The percentages are applied to VIFT and give nothing useful on a MAS from a beep test or a VAMEVAL. VIFT is 2 to 4 km/h higher than MAS, so the same percentage of MAS gives a slower, different session.
Sources
- Buchheit M., “The 30-15 Intermittent Fitness Test: accuracy for individualizing interval training of young intermittent sport players”, Journal of Strength and Conditioning Research, 2008 — VIFT as the reference speed for prescribing intermittent running; zones as listed on the 30-15 IFT page. Checked 2026-09-25