Impact Test Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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A practical impact test estimate starts with a clear definition of every quantity on the page. Material calculations are most informative when the load path, cross-section, and elastic property all describe the same physical case. Once those inputs are aligned, the calculation becomes much easier to check and compare.

What this calculator does

This calculator isolates the relationship between Angle of fall (β), Angle of rise (α), Mass of anvil (m) and energy absorbed. That makes it easier to see which input is controlling the result and to distinguish the headline quantity from secondary values shown underneath.

How to use it

For a clean calculation, enter Angle of fall (β), Angle of rise (α), Mass of anvil (m), Acceleration due to gravity (g), Center of rotation to striker distance (S) exactly as defined by the labels and their units. Check the headline value, then scan the supporting metrics for a relationship that should obviously increase or decrease with one input; this is a fast way to catch an entry mistake.

How the calculation works

The pendulum heights are h = S(1−cosβ) before impact and h₁ = S(1−cosα) after impact. Absorbed energy is mg(h−h₁), and impact velocity is √(2gh). The result follows the ideal pendulum-energy model used for Charpy-style reasoning.

Example

Using the default example on the page (Angle of fall (β) = 150 deg; Angle of rise (α) = 30 deg; Mass of anvil (m) = 20 kg; Acceleration due to gravity (g) = 9.80665 m/s²), the calculator returns energy absorbed of 254.784241 J. Before relying on more decimal places, verify the trend by changing one field and checking that the result responds physically.

How to interpret the result

Interpret the energy absorbed in the context of the chosen shape and material inputs. For design comparisons, keep the same convention and make sure a reported stress-like value is being compared with the corresponding material property rather than a different test quantity.

Limitations and notes

This is an ideal pendulum-energy calculation. A standardized Charpy or Izod test also depends on specimen geometry, notch dimensions, striker geometry, machine losses, calibration, and the applicable test standard. The visible planet selector does not change gravity; the entered g value does.