How to calculate the gold price per gram?
Complete guide on converting troy ounces to grams and applying exchange rates.
At a glanceGold is traded globally on interbank markets (LBMA in London and COMEX in New York) in US Dollars per troy ounce (symbol: *ozt*). To determine the exact value of a single gram of gold in Switzerland, three calculations are required: converting the troy ounce into metric grams, applying the live USD/CHF currency exchange rate, and scaling by the karat or millesimal fineness of the item.
The Universal Gold per Gram Formula
One troy ounce is internationally defined as exactly 31.1034768 grams (distinct from the common 28.35 g avoirdupois ounce). The official Swiss calculation formula is:
Formula: 24k Fine Gold Price per Gram (CHF) = [Live LBMA Spot Price in USD ÷ 31.1035] × USD/CHF Exchange Rate
Once the 24k price per gram is established, multiply by the purity ratio of the alloy:
- 24 Karat (999.9‰ Pure Gold): Multiplier = 1.000
- 22 Karat (Krugerrand, 916‰): Multiplier = 0.916
- 21.6 Karat (Vreneli, 900‰): Multiplier = 0.900
- 18 Karat (Luxury Standard, 750‰): Multiplier = 0.750
- 14 Karat (585‰): Multiplier = 0.585
- 9 Karat (375‰): Multiplier = 0.375
Practical Numerical Calculation
Live Scenario in Swiss Francs: Assume spot gold trades at $3,150.00 USD/oz and the USD/CHF exchange rate stands at 0.8850.
- Step 1 — Fine gold per gram in USD: $3,150.00 ÷ 31.1035 g = $101.275 USD per gram.
- Step 2 — Conversion to CHF: $101.275 × 0.8850 = CHF 89.63 per gram of 24k fine gold.
- Step 3 — 18-karat jewelry rate (750‰): CHF 89.63 × 0.750 = CHF 67.22 per gross gram.
- A ring weighing 8.50 grams holds an intrinsic melt value of: 8.50 g × CHF 67.22 = CHF 571.37.
Reference Table: Purity Grades, Multipliers, and Content
| Karat Grade | Fineness (‰) | Fine Gold Ratio (%) | Math Multiplier | Fine Gold in 10g Batch | Typical Swiss Form |
|---|---|---|---|---|---|
| 24K | 999.9‰ | 100.0% | 1.000 | 10.00 g | Minted bars PAMP, Argor, Valcambi |
| 22K | 916.7‰ | 91.6% | 0.916 | 9.16 g | Krugerrand, Sovereign bullion coins |
| 21.6K | 900.0‰ | 90.0% | 0.900 | 9.00 g | Swiss 20 Francs Gold Vreneli |
| 18K | 750.0‰ | 75.0% | 0.750 | 7.50 g | Luxury Swiss watches, fine jewelry |
| 14K | 585.0‰ | 58.5% | 0.585 | 5.85 g | Imported jewelry |
| 9K | 375.0‰ | 37.5% | 0.375 | 3.75 g | Budget commercial jewelry |
Spot Benchmark vs. Real Buyback Payout
- LBMA Spot Price: Interbank price for 400 oz standard London Good Delivery bars.
- Retail Jewelry Price: Reflects craftsmanship, gem setting, brand markup, and retail overhead.
- Scrap Buyback Price: Reflects pure recoverable fine gold minus refining costs and dealer spread (typically 6% to 12% below spot).
Frequently Asked Questions
Why is a troy ounce 31.1035 g rather than 28.35 g? Troy weight dates back to the medieval trade fairs of Troyes, France, and was adopted as the universal benchmark for precious metals.
How often does the gram price update? Spot rates trade continuously five days a week from Sunday evening (Asian open) to Friday evening (New York close), with benchmark LBMA fixings twice daily.
How does GoldPrice24 ensure calculation accuracy? Our platform syncs live LBMA feeds and USD/CHF rates every minute for real-time Swiss accuracy.
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