Lbs to PSI Converter
Turn a load in pounds into a pressure in psi by spreading it over a contact area.
200 lb spread over different areas
| Area | Pressure | Metric |
|---|---|---|
| 1 in² | 200 psi | 1,378.95 kPa |
| 2 in² | 100 psi | 689.48 kPa |
| 5 in² | 40 psi | 275.79 kPa |
| 10 in² | 20 psi | 137.9 kPa |
| 20 in² | 10 psi | 68.95 kPa |
| 50 in² | 4 psi | 27.58 kPa |
| 100 in² | 2 psi | 13.79 kPa |
Pounds alone are not a pressure
Pressure is force divided by the area it acts on, so a load in pounds only becomes psi once you say how much area it presses against:
psi = pounds ÷ area in square inches
200 lb on a 4 x 5 in pad is 200 ÷ 20 = 10 psi. The same
200 lb on a 1 in² spike is 200 psi — twenty times the pressure from an
identical load.
Why the footprint dominates
This is why snowshoes work, why stiletto heels dent floorboards, and why tracked vehicles cross ground that would swallow a wheeled one. Nothing about the weight changes; only the area does. It is also why a knife sharpens by getting thinner rather than heavier.
Getting the area right
Use the real contact patch, not the object's outline. A tyre only touches the road over a patch of a few square inches, a bolted flange bears on the gasket face rather than the whole plate, and a foot in a shoe loads the heel and ball rather than the full sole. Overstating the area understates the pressure, which is the unsafe direction.