Put Both Quantities in the Same Unit
Contained Mass ÷ Total Ore Mass
The calculator first converts the entered ore and contained-material quantities into kilograms so they can be compared directly.
Grade Calculator
Ore Grade Calculator
Calculate the grade of a mineral deposit from the total quantity of ore or mineralized material and the amount of metal or mineral contained within it. View the result as percent, grams per tonne, ppm, and ppb.
Calculate Ore Grade
Enter Resource Data
Calculate Ore Grade
Enter the metal or mineral being evaluated.
Example:
1,000,000 metric tonnes of ore containing 8,000 metric tonnes
of copper equals a grade of 0.8%.
Calculated Grade
Copper Grade
The same calculated concentration expressed in common resource units.
Percent Grade
—
Mass percentage of contained material.
Grams per Tonne
—
Grams of material per metric tonne.
Parts per Million
—
One part per million by mass.
Parts per Billion
—
One part per billion by mass.
Ore quantity
—
Contained material
—
Contained fraction
—
The contained-material quantity cannot be greater than the
total ore or deposit quantity. Check the values and units entered.
How It Works
The Basic Grade Calculation
Ore grade describes how much of a target material is present relative to the total mass of ore or mineralized material.
Calculate the Mass Fraction
Grade Fraction = Contained ÷ Ore
A deposit containing 8,000 tonnes of copper within one million tonnes of ore has a mass fraction of 0.008.
Convert the Fraction Into Grade Units
Fraction × Unit Conversion
That same concentration can then be shown as percent, g/t, ppm, or ppb without changing the underlying grade.
Understanding Grade Units
Different Units Can Describe the Same Concentration
The preferred reporting unit often depends on the commodity and the concentration being discussed.
%
Percent
Common for higher-concentration materials such as many copper, nickel, iron, or potash deposits.
g/t
Grams per Tonne
Frequently used for precious metals such as gold and platinum where economically important concentrations can be small.
ppm
Parts per Million
Used for trace or lower-concentration materials. One ppm by mass is equivalent to one gram per metric tonne.
ppb
Parts per Billion
Useful for very low concentrations, geochemical exploration, and trace-element reporting.
Worked Example
Calculating the Grade of a Copper Deposit
Suppose a reported mineralized resource contains one million metric tonnes of material and an estimated 8,000 metric tonnes of contained copper.
Dividing the contained copper by the total resource gives a mass fraction of 0.008. Multiplying that fraction by 100 gives a copper grade of 0.8%.
The exact same concentration can also be written as 8,000 ppm or 8,000 grams per tonne. Those numbers look very different, but they describe the same concentration.
Copper Grade Example
Total ore quantity
1,000,000 t
Contained copper
8,000 t
Mass fraction
0.008
Percent grade
0.8%
Equivalent ppm
8,000 ppm
Equivalent g/t
8,000 g/t
Calculated grade
0.8% copper
Important Context
Grade Alone Does Not Determine Resource Value
A higher grade can be important, but resource economics also depend on deposit size, geology, mineralogy, recovery, mining method, location, infrastructure, and market conditions.
01
Deposit Size
A lower-grade but very large deposit may contain more total material than a small high-grade deposit.
02
Cutoff Grade
Projects may use a minimum grade threshold when deciding which material is treated as ore.
03
Recovery
Contained material is not the same as material that can actually be recovered during processing.
04
Mineralogy
The form in which a metal occurs can affect processing difficulty, recovery rates, and product quality.
05
Mining Method
Depth, geometry, stripping requirements, and mining approach can significantly affect project economics.
06
Commodity Value
The economic importance of a particular grade depends partly on the resource being mined and its market value.
Resource Profiles
See How Grade Differs by Resource
Different commodities can be reported using very different grade ranges and measurement conventions.
Related Tools
Continue With Resource Calculations
Educational Use
This calculator performs unit conversions and basic mass-based grade calculations from user-entered values. It does not establish a mineral resource, mineral reserve, cutoff grade, economic viability, engineering conclusion, or investment value.
Earth Value Index
Grade Is One Part of the Resource Story
Continue with Earth Value Index resource profiles and calculators to understand contained material, recovery, reference value, supply, and real-world resource uses.