Standard penetration number, N₆₀

Consistency

Unconfined compression strength, q_u (KN/m²)

0 - 2

Very soft

0 - 25

2 - 5

Soft

25 - 50

5 - 10

Medium stiff

50 - 100

10 - 20

Stiff

100 - 200

20 - 30

Very Stiff

200 - 400

˃30

Hard

˃400