Ounces to Grams Conversion
1 oz = 28.35 grams
One ounce equals 28.35 grams. Simple math, but the real challenge is knowing which ounce you're dealing with. The US uses two different ounces: the avoirdupois ounce (28.35g) for most ingredients, and the fluid ounce (29.57ml) for liquids. They're not the same thing. An ounce of flour weighs 28.35 grams. An ounce of water measures 29.57 milliliters, which happens to weigh 29.57 grams because water has a density of 1g/ml.
This confusion causes recipe failures. A British recipe calling for 8 ounces of cream means weight (227g). An American recipe means volume (237ml). The 10ml difference changes custard texture and whipped cream stability. Professional kitchens avoid this mess by using grams for everything.
How to Convert
Multiply ounces by 28.35 to get grams. For 4 ounces: 4 x 28.35 = 113.4 grams. Round to 113g for kitchen use.
Worked example: Your recipe needs 6 ounces of chocolate. Calculate 6 x 28.35 = 170.1 grams. Set your scale to grams, place a bowl on it, hit tare to zero it out, then add chocolate until the display reads 170g.
For quick mental math, remember that 1 oz is roughly 30g. Your answer will be about 5% high, but close enough for most cooking. Precise baking needs the exact 28.35 multiplier.
Common Mistakes
Confusing weight ounces with fluid ounces. They only match for water. One fluid ounce of honey weighs 42g, not 28.35g, because honey is 1.4 times denser than water. Using the wrong conversion ruins recipes.
Trusting package labels that mix systems. A jar might say '16 oz (454g)' when it actually contains 16 fluid ounces, which is 473ml of product. For thick liquids like honey or molasses, that's a 60-70g difference.
Rounding too early in multi-step conversions. If converting 2.5 pounds to grams, don't round the ounces first. Calculate 2.5 x 16 = 40 ounces, then 40 x 28.35 = 1134g. Rounding to 'about 40 ounces' loses 14 grams.
Pro Tips
Memorize these exact conversions: 1 oz = 28g, 2 oz = 57g, 4 oz = 113g, 8 oz = 227g, 16 oz = 454g. These cover 90% of recipe amounts. Write them on masking tape and stick it to your scale.
Buy a dual-unit scale that shows ounces and grams simultaneously. Costs about $25. You'll catch conversion errors immediately when the numbers don't match what you expect.
For recipes that list both units, like '8 oz (225g)' check which is correct. Many cookbook editors round the conversions. The precise value is 227g, not 225g. Those 2 grams matter in macarons and laminated doughs.
Ingredient-Specific Notes
Chocolate
Baking chocolate comes in 1-ounce squares (28g each). A standard 4-ounce bar equals 113g. Dark chocolate chips are smaller than semi-sweet chips, so 6 ounces by weight gives you different chip counts. Weigh them.
Cheese
Pre-shredded cheese lists weight on the package, but fresh-grated cheese is lighter. 4 ounces of block cheddar (113g) yields about 1 cup when grated. Pre-shredded weighs less per cup because of anti-caking agents.
Nuts
Whole almonds: 1 ounce = 23 almonds = 28g. Sliced almonds: 1 ounce fills about 1/3 cup. Almond flour: 1 ounce = 1/4 cup. The form changes the volume dramatically but weight stays constant.
Meat
Raw meat loses 25% of its weight when cooked. 4 ounces raw ground beef (113g) becomes 3 ounces cooked (85g). Recipes should specify raw or cooked weight. Most mean raw unless stated otherwise.
Pasta
Dry pasta doubles in weight when cooked. 2 ounces dry (57g) becomes 4 ounces cooked (113g). Long pasta like spaghetti: 2 ounces = a bundle the diameter of a quarter = one serving.
Frequently Asked Questions
Is 1 oz always 28 grams?
For weight, yes. One avoirdupois ounce always equals 28.35 grams, rounded to 28g for cooking. But fluid ounces measure volume, not weight. One fluid ounce of water weighs 29.57g. One fluid ounce of oil weighs about 26g. One fluid ounce of honey weighs 42g. The confusion between weight ounces and fluid ounces causes more recipe failures than any other measurement issue.
How many grams in 8 ounces?
8 ounces equals 227 grams (8 x 28.35 = 226.8, rounded to 227g). This is exactly half a pound or 2 sticks of butter. Many recipes round this to 225g, which is close enough for most cooking but not for finicky pastries. An 8-ounce block of cream cheese is exactly 227g. Recipes often call for '8 oz (1 cup)' of ingredients like sour cream, but that's mixing weight and volume measurements.
Why do American recipes use ounces instead of grams?
Historical momentum. The US standardized on the avoirdupois system in the 1800s. Grandma's recipe cards use ounces, so cookbooks kept using them. Digital scales that display grams cost the same as ounce-only scales now, but weren't common in American kitchens until the 2000s. Younger recipe developers often include both units. Professional pastry chefs have used grams for decades because precision matters more than tradition in commercial baking.
Should I round 28.35 to 28 or 30?
For cooking, round to 28g. For baking, use 28.35g or keep extra decimal places until the final calculation. Example: 5 ounces x 28 = 140g (simplified). 5 ounces x 28.35 = 141.75g, round to 142g (accurate). That 2g difference won't ruin a stew but might affect macaron shells. For mental math while shopping, use 30g per ounce to estimate prices and quantities.
Do I need to convert ounces to grams?
Not if your scale has both units. Press the unit button to switch between oz and g. But knowing the conversion helps you spot errors. If a recipe says '10 oz (250g)' something's wrong, because 10 oz = 284g. Many European recipes translated to English contain these errors. Converting everything to grams eliminates confusion and gives consistent results. Professional bakers work exclusively in grams for this reason.