The 400m Hurdles Calculator is a training tool. To get more comfortable with hurdling, setting up hurdles right is a condition to get most out of your workout.
By moving the hurdles closer together making less steps, you can focus more on technique and less on running. These are typical situations where the calculator can help:
You want to do a training with a 6-step rhythm. The training should simulate the 400mH rhythm where you normally run 15 steps (over 35 meters). But how far apart should the hurdles be?
You enter 35m and 15 steps as reference, and voila, at 6-steps the correct distance appears. But you can also start from any other number of steps and distance, someone comfortable doing 3 steps at 8 meters, can now easily move up to 5 steps.
Because the hurdle passage is usally longer than the step length, the calculator needs to take this into account. This is done by passage setting. Because this is not the same for everyone, you can tweak the passage to your needs. Stick to 'normal' to start. When consistently experiencing hurdles too close or too far apart, you can experiment with 'short' and 'long' variants. Generally, shorter and less experience hurdlers will tend towards Long where advanced and taller hurdlers tend more towards Short.