Angle of Repose Calculator

Your details

Choose what to calculate. "Angle from heap geometry" uses the height and base radius of a poured pile. The other two modes convert between angle and friction coefficient.
Vertical height of the conical pile measured from the base to the apex. Must be greater than zero.
cm
Radius of the circular base of the cone (half the base diameter). Must be greater than zero.
cm
Angle of reposePassable / Poor flow
35.27degrees

Steepest stable slope angle of the granular pile

Static friction coefficient (μs)0.7072
Angle in radians0.6156
Flowability classPassable
H : R slope ratio1 : 1.41 (H : R = 0.7072)
35.27 deg
Excellent flow<25Good / Fair flow25-35Poor / Cohesive35-45Very poor flow45+

Angle of repose: 35.27 degrees - Passable.

  • The friction coefficient is approximately 0.7072, meaning that for every unit of normal force, the friction force is 0.707 units.
  • Angles between 30 and 40 degrees are typical of dry sand, gravel, and coal. Hopper half-angles should be kept above the angle of repose to ensure reliable discharge.
  • The angle of repose is an approximate screening test. For silo or hopper design, supplement it with a shear-cell test (Jenike or ring shear) to determine the actual flow factor.

Next stepTo improve accuracy, repeat the heap test at least three times and average the results; surface roughness, humidity, and pour height all affect the measured angle.

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