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Cut Off Grade Calculator

Work out cut off grade instantly with clear inputs, formula shown and shareable results.

About Cut Off Grade Calculator

Break-even cut-off grade is the grade at which recoverable metal value just covers mining plus processing cost. The marginal cut-off, used for material already broken and hauled, covers processing cost only and is therefore lower — which is why mined stockpiles are sometimes processed at grades below the break-even figure.

Formulas

Break-even cut-off

Cut-off grade = (mining + processing cost) / (metal price per gram x recovery)

Marginal cut-off

Marginal cut-off = processing cost / (metal price per gram x recovery)

Worked example

With the default values below, Cut Off Grade Calculator returns Break-Even Cut-Off Grade of 0.2758. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mining Costminimum 0 per tonne ore
3.5 per tonne ore
Processing And G&A Costminimum 0 per tonne ore
12 per tonne ore
Metal Priceminimum 0 per ounce
1,900 per ounce
Metallurgical Recoveryaccepts 0.01–100 %
92 %

Results

Break-Even Cut-Off Grade
0.2758
Marginal Cut-Off Grade
0.2135
Total Unit Cost
$15.50
Metal Value Per Gram
$61.0864

Step by step

  1. 1Values used
  2. 2Break-even cut-off
  3. 3Marginal cut-off
  4. 4Break-Even Cut-Off Grade= 0.2758
  5. 5Marginal Cut-Off Grade= 0.2135
  6. 6Total Unit Cost= 15.50
  7. 7Metal Value Per Gram= 61.0864

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does cut-off grade change with metal price?

Higher prices make lower grades pay, expanding reserves without any new drilling. That is why reserve statements must state the price assumption used.

Should cut-off grade be optimised over time?

Yes. Lane's theory shows the optimal cut-off varies with which part of the operation is the bottleneck — mine, mill or market — and typically starts high and declines over the mine life.

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