22
Oct
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Why Seat Edge Shape Matters More Than You Think

Posted on by Office Chairs Canada

The curve that keeps circulation flowing.

Chair Knowledge Base Toronto & GTA Ergonomics

When I compare chairs in our Vaughan showroom, the seat front edge changes comfort more than most people expect. A smooth “waterfall” edge keeps blood flowing under your thighs; a sharp, flat edge doesn’t.

The Pressure Point You Don’t See

A hard, flat seat edge can press into the underside of your thighs, especially when the chair is a bit too high or the seat is too deep. That pressure slows circulation and leads to tingling, heavy legs by the afternoon. Waterfall edges curve down so your weight lands on the seat pan, not the edge.

Quick test: slide two fingers under your thigh at the front edge while seated. If they’re pinched hard, lower the seat 1–2 cm or choose a seat with a waterfall front.

Flat vs. waterfall seat edge showing pressure distribution under thighs
Waterfall edge reduces pressure under the knees; flat edge concentrates it.
Flat Edge
Common on budget chairs; can dig into thighs if height/depth aren’t dialed in.
Waterfall Edge
Curved front reduces pressure under knees and keeps circulation moving.
Ideal Setup
Seat height just below the kneecap; keep a 2–3 finger gap behind the knees.
TL;DR: Choose a seat with a waterfall front and set height ~1–2 cm below your kneecap; keep 2–3 fingers of space behind the knees.

Small details make long days easy. If your legs feel heavy by noon, check the seat edge first—then fine-tune height and depth.

Office Chairs Canada