Ore grade is the concentration of a valuable metal within a bulk ore sample, expressed as the mass of metal per unit mass of ore. Common units are grams per tonne (g/t) for precious metals, mass percentage (%) for base metals like copper or iron, and troy ounces per tonne (oz/t) used in North American gold reporting.

How is ore grade calculated?

Ore grade = (mass of metal) / (mass of ore). For g/t, divide the metal mass in grams by the ore mass in tonnes. For percentage, divide the metal mass by the ore mass using the same units and multiply by 100. For oz/t, divide the metal mass in troy ounces by the ore mass in tonnes. This calculator handles all unit conversions automatically.

What is a good gold ore grade?

This depends on the mining method and deposit type. Open-pit gold mines typically require grades above 0.5 g/t to 1 g/t to be economic, while high-grade underground deposits can be profitable at grades of 5 g/t to 30 g/t or more. Bonanza grades can exceed 100 g/t.

How do I convert g/t to percentage?

Divide the g/t value by 10,000. For example, 10 g/t = 0.001%. Conversely, multiply percentage by 10,000 to get g/t. This calculator performs this conversion automatically in the results panel.

What is the difference between g/t and oz/t?

Both are mass-per-tonne ratios but use different mass units for the metal. g/t uses grams, while oz/t uses troy ounces (1 troy oz = 31.1035 g). To convert: divide g/t by 31.1035 to get oz/t, or multiply oz/t by 31.1035 to get g/t.

Can this calculator be used for any metal?

Yes. The ore grade formula is universal — it applies to gold, silver, copper, nickel, lithium, or any other metal. The choice of reporting unit (g/t vs. % vs. oz/t) is a convention that varies by commodity and region.

Ore Grade Calculator

Name: Ore Grade Calculator
Availability: InStock
Author: Nham Vu

Enter the mass of metal recovered and the mass of ore sample to instantly compute ore grade in g/t, %, and oz/t.

Sample Data

Mass of Metal Recovered

Mass of Ore Sample

Ore Grade Results

Enter sample data and click Calculate

Typical Ore Grade Ranges by Commodity

Metal	Typical Grade	Unit	Notes
Gold	0.5 – 30	g/t	Open-pit cut-off ~0.5 g/t; underground ~2–5 g/t
Silver	30 – 500	g/t	Often reported alongside gold in polymetallic deposits
Copper	0.3 – 2	%	Porphyry cut-off ~0.3%; high-grade veins >2%
Nickel	0.5 – 3	%	Laterite & sulphide deposits; cut-off ~0.5%
Iron	25 – 65	%	Direct-shipping ore typically >60% Fe

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Summary

Enter the mass of metal recovered and the mass of ore sample to instantly compute ore grade in g/t, %, and oz/t.

How it works

Enter the mass of metal recovered from the assay or sample.
Select the unit for the metal mass: milligrams (mg), grams (g), or kilograms (kg).
Enter the total mass of the ore sample.
Select the unit for the ore mass: grams (g), kilograms (kg), or tonnes (t).
Click Calculate to view the ore grade expressed in g/t, %, and oz/t.
Use Reset to clear all fields and start a new calculation.

Use cases

Reporting drill core assay results for gold, silver, copper, or other metals.
Evaluating whether a deposit meets cut-off grade thresholds for economic viability.
Converting between g/t and percentage for resource estimation reports.
Cross-checking laboratory fire-assay results before submitting to the mine plan.
Teaching ore geology and resource evaluation in mining or geological engineering courses.
Quick field estimation of ore quality from portable XRF or panning results.
Comparing grades across multiple sample intervals along a drill hole.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu