Air Density Calculator
Calculate air density from pressure, temperature, and humidity using the ideal gas law. Includes altitude reference table and moist air corrections.
Gold Weight Calculator
Calculate gold weight in grams, troy ounces, and pennyweights. Karat purity analysis with value estimation for coins, bars, and jewelry.
Total Mass⧉
31.103
0.0311 kg · 1.0000 troy oz
Pure Gold Content⧉
31.072
99.9% purity (24K)
Alloy Content⧉
0.031
Non-gold metals (Cu, Ag, etc.)
Estimated Value⧉
$2,347.61
At $2,350/troy oz
Volume⧉
1.610
Density ≈ 19,320 kg/m³
Troy Ounces⧉
1.0000
20.00 dwt · 1.0971 oz avdp
Composition
Gold 99.9%
Alloy 0.1%
| Karat | Purity | Pure Gold (g) | Density (kg/m³) | Est. Value (USD) |
|---|---|---|---|---|
| 24K | 99.9% | 31.072 | 19,320 | $2,347.61 |
| 22K | 91.7% | 28.512 | 17,800 | $2,154.21 |
| 18K | 75.0% | 23.327 | 15,600 | $1,762.47 |
| 14K | 58.3% | 18.142 | 13,600 | $1,370.73 |
| 10K | 41.7% | 12.961 | 11,600 | $979.23 |
| 9K | 37.5% | 11.664 | 11,200 | $881.24 |
Planning notes, formulas, and examples
About the Gold Weight Calculator
Gold is measured differently from most materials. Precious metals use the troy ounce, which is heavier than the everyday ounce, and karat tells you how much of the item's mass is actually gold. This calculator handles those conversions directly.
Enter a gold item's mass in grams, kilograms, troy ounces, avoirdupois ounces, pounds, or pennyweights, then choose the karat purity. The page reports the total mass, pure gold content, alloy content, volume, and an estimated value based on the current gold price.
For coins and bars, you can also enter dimensions to see whether the stated mass is consistent with the object's geometry. That makes the page useful for jewelry, bullion, and appraisal checks.
When This Page Helps
Gold pricing depends on the unit system as much as on the spot price. A small mismatch between grams, troy ounces, and purity can change the value materially, so keeping the conversions and valuation together is the main reason to use this page.
How to Use the Inputs
- Select a preset (1 oz coin, 400 oz bar, wedding band, etc.) or enter mass manually.
- Choose the mass unit: grams, kg, troy oz, avoirdupois oz, pounds, or pennyweights.
- Select the karat purity (24K, 22K, 18K, 14K, 10K, or 9K).
- Optionally enter dimensions (cylinder for coins, bar for ingots) to estimate volume.
- Enter the current gold spot price in USD per troy ounce.
- Read pure gold content, estimated value, and the karat comparison table.
Formula used
Pure gold mass = Total mass × Karat purity fraction. Troy ounces = grams / 31.1035. Pennyweights = grams / 1.55517. Value = Troy ounces (pure) × Price per troy oz. Volume = Mass / Density.Example Calculation
Result: 1.000 troy oz, $2,347.65
A 31.103 g coin at 24K (99.9%) contains 31.072 g pure gold = 0.999 ozt. Value = 0.999 × $2,350 = $2,347.65.
Tips & Best Practices
- Always use troy ounces for precious metals. A 1 oz gold coin = 31.1 g, not 28.3 g.
- Scrap gold is typically paid at 70–90% of melt value, depending on the refiner.
- The gold-silver ratio (gold price ÷ silver price) is a common metric for precious metal investors; it typically ranges from 50:1 to 80:1.
- For density testing: weigh the item, then measure water displacement. If density ≈ 19.3 g/cm³, it is likely 24K. Lower karats have lower density.
- Gold weight is sometimes expressed in tola (1 tola = 11.664 g) in South Asian markets.
Gold Weight Units Reference
| Unit | Grams | Troy Ounces | |---|---|---| | 1 gram | 1.000 | 0.03215 | | 1 troy ounce | 31.1035 | 1.000 | | 1 avoirdupois ounce | 28.3495 | 0.9115 | | 1 pennyweight (dwt) | 1.5552 | 0.05000 | | 1 tola | 11.6638 | 0.37500 | | 1 tael (Chinese) | 37.429 | 1.20337 | | 1 baht (Thai) | 15.244 | 0.49000 |
Karat System Explained
The karat system divides gold into 24 parts. Pure gold is 24/24 = 100%. Each karat represents 4.167% gold content. Common alloys:
- **24K**: 99.9% gold; investment bars and coins - **22K**: 91.7% gold; coins (Krugerrand, Sovereign) - **18K**: 75.0% gold; fine jewelry (Europe, Asia) - **14K**: 58.3% gold; standard US jewelry - **10K**: 41.7% gold; minimum legal "gold" in the US
The remaining percentage consists of other metals: copper gives rose/red tones, silver produces green gold, nickel or palladium makes white gold.
Sources & Methodology
Last updated:
Frequently Asked Questions
1 troy ounce = 31.1035 g; 1 avoirdupois ounce = 28.3495 g. Troy ounces are about 10% heavier. Precious metals are always traded in troy ounces.
A standard "Good Delivery" bar weighs 400 troy ounces (12.4 kg). At $2,350/oz, it is worth about $940,000.
Commercially, 24K is 99.9% pure (three nines fine). Ultra-high purity gold (99.99% or 99.999%) exists but is used only in electronics and research.
Pure gold is too soft for everyday wear. Alloys with copper, silver, or palladium add hardness. 14K and 18K are the most common jewelry alloys.
A pennyweight (dwt) = 1/20 troy ounce = 1.555 g. It is commonly used by jewelers in the US for pricing gold jewelry.
Common methods include acid testing, specific gravity testing (gold is very dense at 19.3 g/cm³), and electronic gold testers. Professional assay is the most accurate.
More in this topic
Angle of Repose Calculator
Calculate the angle of repose for granular materials. Find pile height, volume, slope ratio, and stability from friction coefficient and density.
Angle of Twist Calculator
Calculate angle of twist, shear stress, and torsional stiffness for solid or hollow shafts under torque. Compare materials side by side.