How to Use This Gold Weight Calculator
This calculator helps you estimate pure gold content and melt value from almost any common unit: grams, kilograms, troy ounces, standard ounces, tola, pennyweight, or grains. It is useful for jewelry owners, pawn shop comparisons, coin collectors, and anyone buying or selling scrap gold.
To use it, enter the total weight, select the unit, choose the karat purity, and provide the current gold price per troy ounce. If a buyer charges a fee or discount, add that in the fee field to estimate your potential payout.
Why Gold Is Measured in Troy Ounces
Gold markets quote prices in troy ounces, not regular (avoirdupois) ounces. One troy ounce equals 31.1034768 grams, while one standard ounce equals 28.349523125 grams. That difference matters. If you mix them up, your value estimate can be significantly off.
Quick Unit Reference
- 1 troy ounce (ozt) = 31.1034768 grams
- 1 ounce (oz, avoirdupois) = 28.349523125 grams
- 1 kilogram = 1,000 grams
- 1 tola = 11.6638038 grams
- 1 pennyweight (dwt) = 1.55517384 grams
- 1 grain = 0.06479891 grams
Understanding Karat and Purity
Karat describes how much pure gold is inside an alloy. The formula is simple: Purity = Karat / 24.
- 24K = 99.9%+ pure gold (investment bars and some coins)
- 22K = 91.67% pure (common in many regions for jewelry)
- 18K = 75% pure
- 14K = 58.5% pure
- 10K = 41.7% pure
Jewelry often includes other metals for strength and color, so two pieces with identical total weight can have very different gold value.
Gold Value Formula
The calculator follows this workflow:
- Convert total weight into grams
- Convert grams into troy ounces
- Find pure gold weight using karat purity
- Multiply pure troy ounces by spot price
- Subtract fee percentage (if applicable)
This gives you an estimated melt value, not necessarily a final retail or resale quote. Dealers may pay below spot and can apply handling, assay, or refining deductions.
Example Calculation
Suppose you have a 30 g bracelet at 18K and spot is $2,300/ozt:
- Purity = 18 / 24 = 0.75
- Pure gold weight = 30 × 0.75 = 22.5 g
- Pure troy ounces = 22.5 / 31.1034768 ≈ 0.7234 ozt
- Melt value = 0.7234 × 2,300 ≈ $1,663.82
If a 5% deduction applies, estimated payout becomes about $1,580.63.
Buying and Selling Tips
When Selling Gold
- Weigh items separately by karat group
- Request quotes from multiple buyers
- Ask whether quote is based on gross weight or pure gold weight
- Check if testing/assay fees are included
When Buying Gold
- Verify karat marks and request documentation
- Know the day’s spot price before negotiating
- Compare premium over melt value for coins/bars
- Understand buyback policy and spread
Common Mistakes to Avoid
- Using standard ounces instead of troy ounces
- Ignoring karat purity and valuing total metal as pure gold
- Forgetting dealer discounts, fees, or spread
- Not updating spot price before each valuation
Final Thoughts
A solid gold weight calculator gives you a realistic starting point before any transaction. Use it to estimate scrap gold value, compare buyer offers, and make informed decisions. For high-value items, consider professional testing and written quotes for best accuracy.