Grams to Ounces Converter — Convert Grams to ounces
Convert grams to ounces with the exact factor, a common-values table, and the formula shown.
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Grams to Ounces Converter
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Grams to Ounces — the Quick Answer
One gram equals 0.035274 ounces (rounded to six significant figures). Going the other way, one ounce equals 28.3495 grams. These factors follow directly from the 1959 international pound definition: 1 lb = 0.45359237 kg exactly, and 1 oz = 1/16 lb exactly, so 1 oz = 0.45359237 ÷ 16 = 0.028349523125 kg = 28.349523125 g.
In cooking and baking, the practical rule is 1 oz ≈ 28 g — close enough for a pinch of spice but not for scaling a patisserie recipe. For postal and shipping rates, use the full 0.035274 oz/g factor; even a few grams over a rate boundary can change the postage class. For nutrition labels and food science, grams are the primary unit; ounces appear mainly on US packaging.
The Grams-to-Ounces Formula
Grams → Ounces
ounces = grams × 0.035274exact inverse: grams = ounces × 28.349523125
The exact derivation: 1 oz = 1/16 lb = 0.45359237 kg ÷ 16 = 0.028349523125 kg = 28.349523125 g. Therefore 1 g = 1/28.349523125 oz = 0.03527396195... oz. The 0.035274 factor is rounded to six significant figures. For 100 g: 100 × 0.035274 = 3.5274 oz.
Source:NIST Special Publication 811 — Guide for the Use of the International System of Units· National Institute of Standards and Technology
The gram-to-ounce conversion is exact in the same sense as the pound-to-kilogram conversion: it ultimately derives from the 1959 agreement that fixed 1 lb = 0.45359237 kg and from the fact that there are exactly 16 ounces in a pound. No measurement uncertainty enters the chain — only the rounding you choose in your final answer.
Common Gram-to-Ounce Values
The table below spans kitchen staples, postage thresholds, and bulk ingredient quantities. Values use the exact factor 0.035274, rounded to three decimal places. The 28 g and 500 g rows are particularly useful because they align with “one ounce” and “one pound” reference points respectively.
Factor: 1 g = 0.035274 oz; 1 oz = 28.350 g (rounded)
Common grams to ounces conversions
| Scenario | Grams (g) | Ounces (oz) | Everyday reference |
|---|---|---|---|
| 1 g | 0.035 oz | a large paperclip / a raisin | |
| 5 g | 0.176 oz | a teaspoon of sugar | |
| 10 g | 0.353 oz | a US dime weighs ~2.3 g; 10 g ≈ 4 dimes | |
| 28 gRecommended | 0.988 oz | ≈ 1 oz — a standard shot of espresso | |
| 50 g | 1.764 oz | a small chocolate bar | |
| 100 gRecommended | 3.527 oz | a medium apple / common recipe unit | |
| 250 g | 8.818 oz | a block of butter / half a US pound | |
| 500 g | 17.637 oz | ≈ 1.1 lb — half a kilogram of ground meat |
To convert a value not in the table, multiply grams by 0.035274. For example, 340 g (a 12 oz can of soda) × 0.035274 = 11.993 oz ≈ 12 oz. For 1 kg (1,000 g): 1,000 × 0.035274 = 35.274 oz = 2.205 lb.
Worked Examples
Example 1
Convert 100 g of butter to ounces (baking recipe)
- Weight
- 100 g
- Factor
- 0.035274 oz/g
Multiply grams by the conversion factor.
100 × 0.035274 = 3.5274Round to two decimal places for practical cooking.
≈ 3.53 oz
100 g of butter = 3.53 oz. If your recipe calls for a US stick of butter (4 oz = 113.4 g), you would need roughly 113 g.
Most digital kitchen scales toggle between grams and ounces, but if yours only reads ounces, knowing that 100 g = 3.53 oz lets you hit recipe targets within 1–2 g.
Example 2
Convert a 3.5 oz postage letter to grams
- Weight
- 3.5 oz
- Factor
- 28.349523125 g/oz
Multiply ounces by the exact grams-per-ounce value.
3.5 × 28.349523125 = 99.223Round to one decimal place for postal accuracy.
≈ 99.2 g
3.5 oz = 99.2 g. USPS first-class mail is rated in ounces; 3.5 oz is the top of the first-class letter tier (under 3.5 oz qualifies for the lowest rate, so a 99.2 g letter sits right at the boundary).
International post offices quote weights in grams. Knowing the exact gram equivalent of USPS ounce thresholds prevents paying priority rates when first-class applies.
How to Use This Converter
- Enter the weight in grams in the field above.
- The result shows the equivalent in ounces instantly, using the exact factor derived from the 1959 pound definition.
- For other weight pairs — including kilograms, pounds, milligrams, and metric tons — use the all-in-one unit converter.
Common Mistakes
- Confusing fluid ounces with weight ounces. A fluid ounce (fl oz) is a volume unit (29.574 mL in the US system). A weight ounce (oz) is a mass unit (28.35 g). They are close numerically only for water (roughly 1 fl oz of water ≈ 29.6 g ≈ 1.04 oz). For oils, syrups, and other liquids with different densities, never swap the two.
- Using 28 g instead of 28.35 g per ounce. Rounding to 28 introduces a 1.25% error — about 1 g per ounce. On a 500 g batch of cookie dough that converts to 17.6 oz, the 28-gram shortcut gives 17.86 oz — off by 0.22 oz, which may not matter for home baking but can cause problems in food-service scaling.
- Mixing up troy ounces and avoirdupois ounces. The troy ounce (31.1035 g) is heavier than the avoirdupois ounce (28.3495 g). Troy ounces appear on precious-metal bars and bullion. Kitchen scales and postal scales use avoirdupois ounces. This converter handles avoirdupois only.
- Not accounting for packaging weight. For postal rates and parcel shipping, the scale reads the total weight including the envelope or box. When converting a printed gram reading to ounces, the packaging is already included — do not add it again.
Background
Grams, Ounces, and Why Two Systems Still Coexist
The ounce descends from the Roman uncia — one twelfth of a Roman pound (libra). Medieval Europe inherited that twelfth-fraction tradition, but different trades settled on different subdivisions. The apothecary system kept 12 ounces to the pound; the avoirdupois system used in everyday commerce settled on 16 ounces per pound by the 14th century, giving a heavier ounce for coarser goods. The word 'ounce' itself entered English via Old French from the Latin uncia, the same root that gives us 'inch' (one twelfth of a foot in the early Roman system).
The gram came from the metric system launched by France in the 1790s. The system's architects wanted each unit derivable from nature: the meter was one ten-millionth of a pole-to-equator quadrant; the gram was the mass of one cubic centimeter of water at 4°C (its density maximum). One gram is therefore a very small unit — the everyday unit of the metric kitchen is the kilogram (1,000 g) or the 100 g portion commonly seen on European nutrition labels.
For most of the 19th and 20th centuries the US maintained separate customary and metric standards with a conversion factor determined by measurement rather than definition. The 1893 Mendenhall Order tied US customary units to metric prototypes, establishing an early relationship between the pound and the kilogram. But the conversion was stated as a rounded decimal, and the US and UK versions differed slightly. The 1959 international yard-and-pound agreement fixed 1 lb = 0.45359237 kg exactly, making the ounce (1/16 lb) = 28.349523125 g exactly [1]. That seven-digit figure has been the world standard ever since.
Food labeling in the US uses both systems simultaneously: a standard granola bar wrapper might read '28g (1 oz)' — not because the manufacturer measured it twice, but because the gram figure is primary and the ounce is printed as a legally required US customary equivalent. International shippers face the same dual display every time a package crosses the Atlantic. The persistence of two systems is largely cultural and historical; the underlying math has been unified since 1959 [2].
- NIST SP 811 — Pound and ounce definitions, exact metric equivalents · National Institute of Standards and Technology · 2008
- NIST Weights and Measures — US customary units and their SI equivalents · National Institute of Standards and Technology · 2023
Cooking, Postage & Measurement Terms
Quick reference
Grams, ounces & related units
Gram (g)
The SI unit of mass for small quantities. One gram = 1/1,000 of a kilogram. Defined indirectly via the Planck constant since 2019.
- A US dollar bill weighs about 1 g. A paper clip weighs about 1 g. A teaspoon of salt weighs about 5–6 g. European nutrition labels use 100 g as the standard serving reference; US labels use a defined serving size in grams or milliliters.
Avoirdupois ounce (oz)
1/16 of a pound = exactly 28.349523125 g. Used for body weight, postal rates, grocery items, and cooking in the US and UK.
- The word 'avoirdupois' comes from Old French meaning 'goods of weight.' The system — 16 oz/lb, 2,000 lb/short ton — is used in everyday US commercial activity. It is distinct from the troy and apothecary systems used for precious metals and pharmacy.
Troy ounce (ozt)
A heavier ounce used for precious metals: 1 troy oz = 31.1035 g — about 10% heavier than an avoirdupois ounce.
- Gold, silver, and platinum prices are quoted per troy ounce. Never use this converter to convert precious-metal weights; 100 g of gold is 3.215 troy oz, not 3.527 avoirdupois oz. The two ounce types are easily confused on bullion listings.
Fluid ounce (fl oz)
A volume unit: 1 US fl oz = 29.574 mL. Different from a weight ounce (28.35 g). Only numerically similar for water.
- Recipe liquids in US cookbooks are often in fluid ounces: 8 fl oz = 1 US cup = 237 mL. Converting volume to mass requires knowing the liquid's density — for water at room temperature, 1 fl oz ≈ 29.5 g; for honey (density ≈ 1.42 g/mL), 1 fl oz ≈ 42 g.
Milligram (mg)
1/1,000 of a gram. Used for drug doses, supplements, and trace nutrients on labels.
- A standard aspirin tablet is 325 mg = 0.325 g = 0.01146 oz. Nutritional labels list micronutrients in mg: the recommended daily iron intake for adults is 8–18 mg (0.008–0.018 g).
First-class letter weight
USPS first-class mail: up to 3.5 oz (99.2 g) for letters. Over 3.5 oz triggers a higher rate.
- International post offices (Royal Mail, Deutsche Post, etc.) quote letter weights in grams — commonly 20 g, 100 g, and 250 g as rate boundaries. Knowing gram-to-ounce conversion prevents overpaying when switching between mailing destinations.
0.035274 factor
Grams to ounces: multiply grams by 0.035274. Derived from 1 oz = 28.349523125 g (exact), so 1 g = 0.0352739619... oz.
- The 0.035274 rounded value introduces at most 0.0004% error — roughly 0.035 mg per gram converted. For kitchen use, 0.035 is sufficient; for pharmaceutical or precious-metal conversions, use the full 0.0352739619... factor.
100 g serving
European nutrition labels express all nutrients per 100 g. US labels use a per-serving amount, also stated in grams.
- Comparing foods between US and European labels requires converting to a common base. To find calories per 100 g from a US label that shows 280 kcal per 1.5 oz (42.5 g) serving: 280 ÷ 42.5 × 100 = 659 kcal/100 g.
Related Converters and Tools
For the reverse direction — ounces to grams — enter your ounces into the field above and read the grams result, or visit the all-in-one unit converter which handles the full weight spectrum from micrograms to metric tons. For body weight — which mixes pounds, kilograms, and body fat percentage — the BMI calculator accepts kilograms or pounds directly. If you are converting recipe quantities in bulk, the unit converter handles both mass and volume conversions side by side.
Frequently Asked Questions
The most common questions we get about this calculator — each answer is kept under 60 words so you can scan.
What is the grams to ounces conversion factor?
1 g = 0.035274 oz. To convert, multiply your grams value by 0.035274.What is 100 grams in ounces?
100 grams = 3.53 ounces. Multiply 100 by 0.035274 to get the result.How do I convert ounces back to grams?
Divide your ounces value by 0.035274 (or multiply by the reciprocal). The page shows the exact reverse rate.Is this conversion exact or rounded?
The factor itself is exact by international standard; only the displayed result is rounded for readability. Internally full precision is kept.Is the Grams to Ounces converter free?
Yes — free, instant, no signup. All math runs in your browser; nothing is stored.