Ounces ↔ Grams Converter
Convert ounces to grams or grams to ounces for cooking and baking. Bidirectional weight conversions for all ingredients.
Reviewed by the Calcura editorial team · Last reviewed
- Question
- How do I convert ounces to grams?
- Answer
- grams = ounces × 28.3495. This is the exact international avoirdupois ounce used for most US recipes, food labels, and kitchen scales. So 4 oz = 113.4 g, 8 oz = 226.8 g, and 16 oz (1 lb) = 453.6 g. To go the other way: ounces = grams / 28.3495. For cooking, rounding to 28 g per oz is close enough (error under 1.8%).
▸Show formula & caveatsHide formula & caveats
- Formula
grams = ounces × 28.3495 (avoirdupois)- Caveats
- Fluid ounces (fl oz) measure volume, not weight. Don't mix the two.
- Troy ounces (used for precious metals) weigh 31.1035 g — different system, don't confuse with cooking.
- US recipes use weight ounces; UK recipes often mean the same thing, but check the context.
Ounces to Grams Conversion Table
Using the avoirdupois ounce: 1 oz = 28.3495 g.
| Ounces | Grams (rounded) | Grams (exact) |
|---|---|---|
| 0.5 oz | 14 g | 14.17 g |
| 1 oz | 28 g | 28.35 g |
| 2 oz | 57 g | 56.70 g |
| 3 oz | 85 g | 85.05 g |
| 4 oz (¼ lb) | 113 g | 113.40 g |
| 5 oz | 142 g | 141.75 g |
| 6 oz | 170 g | 170.10 g |
| 8 oz (½ lb) | 227 g | 226.80 g |
| 10 oz | 283 g | 283.50 g |
| 12 oz | 340 g | 340.19 g |
| 16 oz (1 lb) | 454 g | 453.59 g |
| 32 oz (2 lb) | 907 g | 907.18 g |
What This Calculator Does
This converter translates between avoirdupois ounces and grams, the two weight systems most home cooks encounter. 1 oz = 28.3495 g exactly (by international agreement since 1959). It handles both directions with a toggle. Use it for weight ounces from US recipes, package labels, or scale readouts — not fluid ounces (which measure volume). For baking, weighing beats volume measurement every time: flour in particular can vary by 30% per cup depending on how it's scooped.
When To Use This Calculator
Reading a US recipe on a metric scale
Recipe calls for '4 oz cream cheese.' On a gram scale: 4 × 28.3495 = 113.4 g. Round to 113 g — well within recipe tolerance.
Buying international chocolate or cheese
A 200 g chocolate bar is 200 / 28.3495 = 7.05 oz, just over half a US 'pound' (16 oz). Useful when a recipe asks for 'an 8 oz bar' and you're shopping metric packaging.
Halving or doubling by weight
A recipe calls for 12 oz flour. Doubling: 24 oz × 28.3495 = 680 g. Weighing to the gram avoids the compounding error of repeated cup measures.
Calculating baker's percentages
Bread with 1 lb flour = 454 g (100%). At 65% hydration, water = 454 × 0.65 = 295 g. Baker's percentages require grams for clean math.
How It Works
The international avoirdupois pound was fixed at exactly 0.45359237 kg in 1959 by agreement among the US, UK, Canada, Australia, New Zealand, and South Africa. Since 1 lb = 16 oz, 1 oz = 0.45359237 / 16 kg = 0.02834952 kg = 28.3495 g. The conversion is exact, not approximate. For mental math during cooking, 1 oz ≈ 28 g is good to about 1%; 1 oz ≈ 30 g is easier arithmetic but introduces 6% error, which matters for baking but not for produce weights.
Formula
grams = ounces × 28.349523125
ounces = grams / 28.349523125
(exact conversion from 1959 international yard and pound agreement)Real-World Example
Scenario
A home baker adapting a King Arthur Flour chocolate chip cookie recipe that lists '8 oz unsalted butter, 10.5 oz all-purpose flour, 7 oz brown sugar' — converting to grams for a digital scale.
Calculation
Butter: 8 × 28.3495 = 227 g (which matches the standard US 2-stick weight, sanity check ✓) Flour: 10.5 × 28.3495 = 298 g Brown sugar: 7 × 28.3495 = 198 g Total dry: ~500 g (feels right for ~24-cookie batch)
Result
Weigh 227 g butter, 298 g flour, 198 g brown sugar. Using grams eliminates the 'spooned vs scooped vs sifted' flour ambiguity — 298 g is 298 g regardless of how it would have measured in cups. Cookie outcomes are measurably more consistent batch-to-batch when weighed.
Common Mistakes to Avoid
Mistake: Confusing weight ounces with fluid ounces
Solution: 8 fl oz of water happens to weigh ~8 oz (water has density 1 g/mL). But 8 fl oz of honey weighs ~12 oz because honey is 1.42 g/mL. Only convert 'oz' to grams when it's weight; fluid ounces require volume-to-mass conversion via density.
Mistake: Rounding 28.35 to 30 in baking
Solution: The 6% error from using 30 g/oz compounds: 10 oz flour becomes 300 g instead of 283 g — a 17 g over-measure that stiffens cookies. Use 28 or 28.35 g/oz for baking, round to 30 only for non-critical ingredients like produce.
Mistake: Using troy ounces instead of avoirdupois
Solution: Troy ounces (31.1 g) apply to precious metals only. All cooking uses avoirdupois ounces (28.35 g). If a kitchen scale has a 'troy oz' mode, don't use it for recipes.
Mistake: Ignoring scale minimum resolution
Solution: A scale with 1 g resolution can't accurately measure 2 g of salt — round-off error is 50%. For small quantities (spices, leavening), use measuring spoons or a 0.1 g precision scale.
Ounces to Grams vs. Related Calculators
Cups to Grams (Flour)
Volume-to-mass converter requiring ingredient density. Use when starting from cup measurements rather than oz.
Grams to Tablespoons
For small-quantity ingredients (yeast, salt, baking powder) where volume is often more practical than mass.
Temperature Converter
For the other half of recipe localization — °F ↔ °C when converting US recipes to metric ovens.
When This Isn't the Right Tool
Fluid-ounce to milliliter conversion
Use instead: 1 US fl oz = 29.5735 mL (volume), not mass. If your recipe says '8 fl oz milk,' use a volume converter or a measuring cup, not this weight tool.
Troy ounces for precious metals
Use instead: Gold, silver, and platinum are sold in troy ounces (31.1035 g). Cooking never uses troy; if you see a scale with a troy mode, ignore it for recipes.
Dietary-label 'oz' (US customary serving)
Use instead: Nutrition labels often list a 'serving' as an odd fractional ounce (e.g., 0.75 oz). Convert to grams for accurate tracking, but note that FDA allows ±20% label tolerance on package contents.
Force / weight confusion
Use instead: Pounds and ounces in food contexts are mass, not force. Don't introduce gravitational factors (g = 9.81 m/s²) — kitchen scales read mass directly.
How to Verify This Calculation
NIST's Handbook 44 (General Code for Weighing and Measuring Devices) lists 1 lb = 453.59237 g. Divide by 16: 28.3495 g/oz. Your digital scale's conversion mode, if present, should match to 0.01 g.
Sources
- NIST — Handbook 44 (Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices) — Defines the exact avoirdupois pound–kilogram relationship (1 lb = 0.45359237 kg) used for all ounce↔gram conversions.
- BIPM — SI Brochure (The International System of Units) — Authoritative source for the kilogram and gram definitions; the gram is 1/1000 kg exactly.
- USDA FoodData Central — US Department of Agriculture's nutrient database — uses grams as its default measure, relied on for recipe-scaling macro and calorie math.
Reviewed by the Calcura editorial team · Last reviewed