Why is the first number always one?

Every area is divided by the sprue base area, so the sprue term becomes one.

Should I enter one gate or all gates?

Enter the sum of all ingate areas. The calculator divides that total by the equal-ingate count.

No. It identifies the smallest aggregate section entered; losses, branching and transient filling require separate analysis.

Use the approved casting method. This calculator measures a proposed ratio and does not select one.

Foundry & Forging calculator

Normalize sprue, total runner and total ingate areas to compare the geometry of one gating system.

Normalize sprue, total runner and total ingate areas to compare the geometry of one gating system.

Normalized gating ratio = 1 : total runner area ÷ sprue area : total ingate area ÷ sprue area
Area per equal ingate = total ingate area ÷ ingate count
Smallest aggregate section = min(sprue area, total runner area, total ingate area)

Sprue Base Area: Effective cross-section at the bottom of the sprue.
Total Runner Area: Sum of parallel runner cross-sections at the comparison station.
Total Ingate Area: Sum of all ingate cross-sections serving this casting.
Equal Ingates: Number of equally sized ingates in the drawing.

Best suited to a smaller sprue raises the downstream Ratios, a larger sprue lowers the downstream ratios.
Area ratios alone do not establish flow rate, filling quality or actual choke behavior.

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Why is the first number always one? Every area is divided by the sprue base area, so the sprue term becomes one.
Should I enter one gate or all gates? Enter the sum of all ingate areas. The calculator divides that total by the equal-ingate count.
Does the smallest area prove the choke location? No. It identifies the smallest aggregate section entered; losses, branching and transient filling require separate analysis.
What ratio is best for my alloy? Use the approved casting method. This calculator measures a proposed ratio and does not select one.

Last reviewed 2026-10-06.