Foundry & Forging worked example

Gating Ratio Calculator with sprue choke cross-section of 1.2 in²: a worked example

This worked example runs the gating ratio calculator numbers for a tougher week than the baseline: sprue choke cross-section of 1.2 in² instead of the typical 2.4 in². Calculate a gating ratio from sprue, runner, and ingate area or another approved gating-system basis.

The inputs for this scenario

  • Sprue choke (upstream) cross-section: 1.2 in² (the input this scenario stresses; the baseline uses 2.4)
  • Total ingate (downstream) cross-section: 3.6 in² (held at the documented default)
  • Reporting unit conversion multiplier: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gating Ratio Calculator ratio = upstream gating area ÷ downstream ingate area.
  • Gating Ratio Calculator ratio works out to 0.33 x at these inputs, and this is the headline figure for the scenario.
  • Raw ratio works out to 0.33 value at these inputs.
  • Conversion factor works out to 1 x at these inputs.
  • Downstream ingate area works out to 3.6 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where sprue choke cross-section sits at 2.4 in² and the headline result is 0.67 x, this scenario comes in 50% below the baseline at 0.33 x.
  • Use it when designing or troubleshooting a gating system to set fill velocity and decide between pressurized and unpressurized layouts. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Gating Ratio Calculator ratio: 0.33 x (headline result)
  • Raw ratio: 0.33 value
  • Conversion factor: 1 x
  • Downstream ingate area: 3.6 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Gating Ratio Calculator calculator, set sprue choke cross-section to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.