An avoirdupois ounce is 1/16 pound.
Ounces to Troy ounces Converter — oz to oz t
Convert Ounce (oz) to Troy ounce (oz t) using the exact conversion factor (1 ounce = 0.9114583333 troy ounce). See the formula, worked examples, conversion table, history, and common uses.
Ounces to Troy ounces converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
Context values
Some unit families need one extra value for a physically accurate result.
A troy ounce is exactly 31.1034768 grams.
Result = input x 0.02834952313 / 0.0311034768.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Ounces to Troy ounces
Weight conversions between Ounce and Troy ounce come up constantly in everyday commerce, shipping, and cooking, since US packaging is usually labeled in pounds while most of the rest of the world uses kilograms. Ounce is most often used for us cooking and recipe measurement (small quantities).
Formula
troy ounces = ounces × 0.911458333333
This factor comes from each unit's defined relationship to the category's base unit: 1 ounce equals 0.028349523125 base units, and 1 troy ounce equals 0.0311034768 base units, so dividing one by the other gives the direct ounce-to-troy ounce factor of 0.911458333333.
Simple example
1 oz × 0.9114583333 = 0.9114583333 oz t
1 ounce = 0.9114583333 troy ounces.
Real-world example
50 oz × 0.9114583333 = 45.57291667 oz t
50 ounces = 45.57291667 troy ounces.
Conversion table
| Ounce (oz) | Troy ounce (oz t) |
|---|---|
| 1 oz | 0.9114583333 oz t |
| 5 oz | 4.557291667 oz t |
| 10 oz | 9.114583333 oz t |
| 25 oz | 22.78645833 oz t |
| 50 oz | 45.57291667 oz t |
| 100 oz | 91.14583333 oz t |
Reverse conversion: Troy ounce to Ounce
0.9114583333 oz t × 1.097142857 = 1 oz
0.9114583333 troy ounces = 1 ounces.
ounces = troy ounces × 1.09714285714
For a page dedicated to this direction, see Troy ounce to Ounce.
Understanding the Ounce
Ounce (oz) measures mass. The avoirdupois ounce is 1/16 of a pound: exactly 28.349523125 grams. It is classified as a US/imperial customary unit.
Where it's used: United States (cooking, postal, retail) United Kingdom (informal/retail use)
Avoirdupois ounce vs. troy ounce. The everyday ounce (avoirdupois, 28.35 g) used for cooking and shipping is a different, smaller unit than the troy ounce (31.10 g) used for precious metals like gold and silver — this page uses the everyday avoirdupois ounce.
Uses of the Ounce today
- US cooking and recipe measurement (small quantities)
- US postal and shipping weight
- Precious metals (troy ounce, a related but distinct unit)
History of the Ounce
The ounce descends from the Roman 'uncia' (a twelfth part), inherited through medieval English weight systems; the avoirdupois ounce (for general goods, as opposed to the troy ounce for precious metals) became standard for everyday trade, fixed at exactly 28.349523125 g via the pound's 1959 international standardization.
Historical origin. Ounce was not the invention of a single named person; it developed through the process described above.
Understanding the Troy ounce (oz t)
A troy ounce is exactly 31.1034768 grams.
Ounce — sources
- NIST — International yard and pound (1959) — Basis for the modern ounce via the standardized pound.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many troy ounces are in 1 ounce?
1 ounce equals 0.9114583333 troy ounces, using the exact defined conversion factor rather than an estimate.
How do I convert ounce to troy ounce?
Multiply the ounce value by 0.9114583333. The converter above does this instantly to whatever precision you set.
How do I convert troy ounce back to ounce?
Use the reverse factor: 1 troy ounce equals 1.097142857 ounces. You can also use the swap control in the converter above to flip the direction instantly.
What is a ounce?
Ounce (oz) measures mass. The avoirdupois ounce is 1/16 of a pound: exactly 28.349523125 grams. It is classified as a US/imperial customary unit.
What is a troy ounce?
Troy ounce (oz t) is a unit of mass/weight.
Is the ounce to troy ounce conversion exact?
Yes. The avoirdupois ounce is 1/16 of a pound: exactly 28.349523125 grams. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between avoirdupois ounce vs. troy ounce?
The everyday ounce (avoirdupois, 28.35 g) used for cooking and shipping is a different, smaller unit than the troy ounce (31.10 g) used for precious metals like gold and silver — this page uses the everyday avoirdupois ounce.
Where is the ounce still used today?
United States (cooking, postal, retail) United Kingdom (informal/retail use)