What is the PFL Rebound Index?

Last updated: 2026-10-29

The PFL Rebound Index is the percentage of its original thickness that a lattice footbed recovers 30 seconds after a 20 kg load, held for 60 seconds on the forefoot, is removed. A score of 100 means full recovery. It is a method defined by PrintFoot Lab, not an industry standard.

Formula

PFL Rebound Index = (thickness 30 s after unloading ÷ original thickness) × 100

Protocol

Step	What to do
1. Condition	Keep the slide at about 22 °C for 2 hours.
2. Measure	Measure forefoot thickness at the ball of the foot with calipers (original thickness).
3. Load	Place a 40 mm diameter disc on that spot and apply 20 kg for 60 seconds.
4. Unload	Remove the load and start a timer.
5. Re-measure	Measure the same spot at 30 seconds.
6. Repeat	Repeat three times on fresh spots and average.

Worked example (illustrative)

Original thickness	Thickness at 30 s	PFL Rebound Index
18.0 mm	17.1 mm	95

How to read it

Score	Our reading
95–100	Recovers almost fully within 30 s
85–94	Slow recovery; may feel "memory-foam like"
Below 85	Noticeable short-term set

The index describes short-term recovery only. Long-term flattening needs repeated-load testing.