Ore Grade Calculator
Convert any ore grade between g/t, ppm, %, oz/t and oz/ton (1 oz/ton = 34.2857 g/t), or work out contained metal from tonnage × grade, the recoverable value per tonne, the break-even cut-off grade and a gold- or copper-equivalent grade.
One gram per tonne (g/t) equals 1 ppm, 0.0001 % and 0.029167 troy ounces per short ton; one troy ounce per short ton (oz/ton) equals 34.2857 g/t, and one troy ounce per metric tonne equals 31.1035 g/t.
Use the Ore Grade Calculator
Ore grade converter — g/t, ppm, %, oz/t, oz/ton
Type a grade in any unit; all other units update as you type.
- g/t
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- ppm
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- ppb
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- %
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- kg/t
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- oz/t
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- oz/ton
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- lb/ton
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Sample Assay Parameters
Calculation Results Assay Grade
Enter inputs and select Calculate
Value per tonne and break-even cut-off grade
Grade × tonnage gives contained metal; price × recovery turns it into value. Prices are examples — enter current prices.
Cut-off = cost per ton ÷ (price per unit of metal × recovery). Royalties, refining and transport charges and mining dilution are not included.
Metal equivalent grade (AuEq, CuEq)
Eq = grade₁ + grade₂ × (price₂ × recovery₂) ÷ (price₁ × recovery₁), with both grades converted to the same mass basis.
Unit Relationships and Evaluation Limitations
- • 1 g/t = 1 ppm = 0.0001% (10,000 g/t = 1%)
- • 1 troy ounce = 31.1034768 g (NIST SP 811)
- • 1 metric tonne (t) = 1,000 kg = 2,204.6226 lbs
- • 1 short ton (st) = 907.18474 kg = 2,000 lbs
- • 1 oz/st (opt) = 34.28571 g/t (ppm)
- • 1 oz/t = 31.10348 g/t (ppm)
- • Theoretical Insitu vs Recoverable: Contained metal calculations calculate total chemical mass in place, excluding metallurgical recovery efficiency and smelting deductions.
- • Dilution and Mining Loss: Bulk mining introduces barren wall rock (dilution) lowering delivered mill head grade compared to undiluted drill core assays.
- • Dry vs Wet Basis: Ore tonnage and grade must be evaluated on consistent dry metric bases to avoid moisture weight distortion.
Grade conversion table — g/t to oz/ton, oz/t and %
1 g/t = 1 ppm; 1 oz/ton (troy ounce per short ton) = 34.2857 g/t; 1 oz/t (troy ounce per metric tonne) = 31.1035 g/t; 1% = 10,000 g/t.
| g/t (ppm) | oz/ton (short) | oz/t (metric) | % | ppb |
|---|---|---|---|---|
| 0.1 | 0.002917 | 0.003215 | 0.00001 | 100 |
| 0.5 | 0.014583 | 0.016075 | 0.00005 | 500 |
| 1 | 0.029167 | 0.032151 | 0.0001 | 1,000 |
| 2 | 0.058333 | 0.064301 | 0.0002 | 2,000 |
| 3 | 0.0875 | 0.096452 | 0.0003 | 3,000 |
| 5 | 0.14583 | 0.16075 | 0.0005 | 5,000 |
| 10 | 0.29167 | 0.32151 | 0.001 | 10,000 |
| 20 | 0.58333 | 0.64301 | 0.002 | 20,000 |
| 31.103 | 0.90718 | 1 | 0.00311 | 31,103 |
| 34.286 | 1 | 1.1023 | 0.003429 | 34,286 |
| 50 | 1.4583 | 1.6075 | 0.005 | 50,000 |
| 100 | 2.9167 | 3.2151 | 0.01 | 100,000 |
Quick answer
One gram per tonne (g/t) equals 1 ppm, 0.0001 % and 0.029167 troy ounces per short ton; one troy ounce per short ton (oz/ton) equals 34.2857 g/t, and one troy ounce per metric tonne equals 31.1035 g/t. Contained metal is tonnage × grade: 1,000,000 t at 2 g/t holds 2,000,000 g, or 64,301 oz of gold. The break-even cut-off grade is the cost per tonne divided by (metal price per gram × recovery): at $60/t, $2,500/oz and 90% recovery it is 60 ÷ (80.38 × 0.90) = 0.83 g/t.
Examples
| Grade | oz/ton (short) | oz/t (metric) | % | ppm |
|---|---|---|---|---|
| 0.5 g/t | 0.0146 | 0.0161 | 0.00005 | 0.5 |
| 1 g/t | 0.0292 | 0.0322 | 0.0001 | 1 |
| 5 g/t | 0.1458 | 0.1608 | 0.0005 | 5 |
| 10 g/t | 0.2917 | 0.3215 | 0.001 | 10 |
| 34.2857 g/t | 1 | 1.1023 | 0.0034 | 34.29 |
| 1% (10,000 g/t) | 291.67 | 321.51 | 1 | 10,000 |
Type a grade in the converter, or enter your tonnage, price, recovery and cost to get contained metal, value per tonne and the cut-off grade.
Summary
Ore grade is the concentration of a metal in rock. Precious metals are reported in grams per tonne (g/t, the same as ppm) or troy ounces per ton, base metals in percent. This calculator converts a grade between every common unit, finds the grade of an assay from metal and sample mass, and turns tonnage × grade into contained metal. Add a metal price, metallurgical recovery and the operating cost per tonne to get the recoverable value per tonne, the break-even cut-off grade and the margin, or combine two metals into one equivalent grade (for example gold-equivalent from gold and silver). Troy ounce = 31.1034768 g and short ton = 907.18474 kg (NIST).
How it works
- Type a grade and pick its unit in the converter to see it in g/t, ppm, ppb, %, kg/t, oz/t, oz/ton and lb/ton at once.
- Use "Assay Grade from Sample" to get the grade from a measured metal mass and sample mass, or "Contained Metal from Tonnage" for tonnage × grade.
- In "Value and cut-off grade", enter grade, tonnage, metal price, recovery and cost per tonne to get recoverable metal, value per tonne, margin and the break-even cut-off grade.
- In "Metal equivalent", enter a second metal's grade, price and recovery to express both as one equivalent grade of the main metal.
- Copy the results or change any input; everything recalculates in your browser.
Use cases
- Converting a Canadian or Australian assay in g/t to the oz/ton used in older US reports.
- Turning a drill intercept or a block model grade into contained ounces or pounds.
- Checking whether a stockpile or block is above the break-even cut-off grade.
- Reporting gold-equivalent (AuEq) or copper-equivalent (CuEq) grades for polymetallic ore.
- Estimating the recoverable value per tonne before mining dilution and smelter terms.