How to Convert Ounces to Grams Formula

To convert ounces to grams, multiply the ounces by 28.349523125: grams = ounces × 28.349523125. One ounce equals 28.35 grams, so 8 ounces is 226.80 grams and 16 ounces — one pound — is 453.59 grams. For quick kitchen math, use 28.35 grams per ounce. Convert any weight instantly with our free ounces to grams converter.

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The Short Answer: 28.349523125 Grams per Ounce

One ounce equals 28.349523125 grams exactly. The formula is a single multiplication: grams = ounces × 28.349523125. So 1 ounce is 28.35 grams, 2 ounces is 56.70 grams, 8 ounces is 226.80 grams, and 16 ounces — one pound — is 453.59 grams. The number is exact, not rounded, because the ounce itself is defined in metric terms: since the 1959 international yard and pound agreement, one avoirdupois pound is defined as exactly 0.45359237 kilograms, and one ounce is exactly one sixteenth of that pound, so 453.59237 ÷ 16 = 28.349523125 grams. That definition is why every converter on the internet agrees on 28.349523125 — it is not a measured value that different sources might dispute, it is a definition. For everyday use you can round to 28.35 grams per ounce and your answer will be right to within a thousandth of a gram per ounce, which is far tighter than any kitchen or bathroom scale can measure. If you only need the reverse direction, our grams to ounces converter handles the smaller metric-to-imperial step the same way.

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The Formula, Step by Step

Converting ounces to grams takes three steps, and the worked example below shows each one. Step 1: write down the weight in ounces. Say you have 8 ounces of chocolate. Step 2: multiply by 28.349523125. That is 8 × 28.349523125 = 226.796185. Step 3: round sensibly. For a recipe, 226.80 grams is the right answer; for a science lab, keep 226.796 grams. The rounding rule is the only judgement call in the whole conversion: keep two decimal places for precise work, whole grams for cooking, and one decimal place for anything in between. A common shortcut is to multiply by 28.35 instead of 28.349523125 — the error is 0.00048 grams per ounce, so even on 100 ounces you are off by only 0.05 grams, which no kitchen scale can detect. The same three steps work in reverse if you divide instead of multiply, and our guide to converting pounds to grams shows the same idea one unit up the scale, where the multiplier is 453.59237 instead of 28.349523125.

Ounces to Grams Conversion Table

Here is the conversion for the weights people actually look up, from a single ounce to a hundred. One ounce is 28.35 grams. Two ounces is 56.70 grams. Three ounces is 85.05 grams. Four ounces is 113.40 grams. Five ounces is 141.75 grams. Six ounces is 170.10 grams. Eight ounces is 226.80 grams. Ten ounces is 283.50 grams. Twelve ounces is 340.19 grams. Sixteen ounces is 453.59 grams. Twenty ounces is 566.99 grams. Twenty-five ounces is 708.74 grams. Thirty-two ounces is 907.18 grams. Fifty ounces is 1,417.48 grams. One hundred ounces is 2,834.95 grams. Three patterns are worth noticing. First, every value is just the ounces multiplied by 28.349523125 and rounded to two decimals, so you can extend the table to any weight yourself. Second, the numbers cluster around familiar anchors: 16 ounces is exactly one pound, 32 ounces is exactly two pounds, and 35.27 ounces is almost exactly one kilogram — 35.27396 ounces per kilogram, to be precise. Third, the half-pound mark sits at 8 ounces, which is why so many recipes and serving sizes are written in eighths of a pound: 8 ounces is 226.80 grams, a quarter of a kilogram near enough. If you work with weights across the whole imperial-metric range, our free unit converter covers ounces, grams, pounds, kilograms and stone in one place.

The 28.35 Shortcut: When Rounding Is Fine

Most people who convert ounces to grams do not need 28.349523125 — they need 28.35. The shortcut is simple: 1 ounce ≈ 28.35 grams. The error is 0.00048 grams per ounce, or about 0.002 percent. On an 8-ounce block of chocolate the shortcut gives 226.80 grams instead of 226.796 — a difference of 0.004 grams, which is invisible in any recipe. On a 16-ounce bag the difference is under a hundredth of a gram. The shortcut breaks only where precision matters: pharmacy dosing, laboratory work, precious metals, and anything where a fraction of a percent changes the outcome. A rougher shortcut, 28 grams per ounce, is a different story: it is off by 0.35 grams per ounce, about 1.2 percent, so on a pound it understates the weight by 5.6 grams — enough to matter in baking, where a 5-gram flour error is real. A useful rule is that if the recipe or the label uses whole grams, the 28.35 shortcut is fine; if it uses decimals, use the full 28.349523125. Another handy mental anchor is that 4 ounces is about 113 grams — just over a tenth of a kilogram — so a '4-ounce' item and a '100-gram' item are close cousins but not twins: the 100-gram item is 13 grams lighter.

Ounces and Pounds Together: Compound Weights

Real weights rarely come in whole ounces. A baby weighs 7 pounds 6 ounces, a roast weighs 3 pounds 8 ounces, and the conversion has to handle both parts. The method is to turn everything into ounces first, then convert once. One pound is 16 ounces, so the formula is total ounces = (pounds × 16) + ounces, then grams = total ounces × 28.349523125. Worked example: 3 pounds 8 ounces. The total is 3 × 16 + 8 = 56 ounces. Then 56 × 28.349523125 = 1,587.57 grams. Another example: 7 pounds 6 ounces. The total is 7 × 16 + 6 = 118 ounces. Then 118 × 28.349523125 = 3,345.24 grams. The shortcut version is even easier: turn the whole weight into a decimal number of pounds first — 3 pounds 8 ounces is 3.5 pounds — and multiply by 453.59237, which gives the same 1,587.57 grams. The fraction trick works for any ounce count: 4 ounces is a quarter pound, 8 ounces is half a pound, 12 ounces is three-quarters of a pound, and 1 ounce is 1/16 of a pound, or 0.0625 pounds. The reverse trip, grams back to ounces, is covered by our grams to ounces formula guide, which uses the same multiply-by-28.3495 logic in the other direction.

The Troy Ounce Trap

There is a second ounce that catches people out: the troy ounce, used for precious metals, weighs 31.1034768 grams — about 2.75 grams more than the ordinary ounce. The trap is that the troy pound is lighter than the ordinary pound (373.24 grams versus 453.59 grams), so people assume the troy ounce must be lighter too. It is not, because the troy pound has only 12 troy ounces while the ordinary (avoirdupois) pound has 16 ordinary ounces: 12 × 31.1034768 = 373.24 grams, while 16 × 28.349523125 = 453.59 grams. If you are converting the weight of gold, silver, or jewelry, check which ounce the source means — a troy ounce of gold is 31.10 grams, and using the ordinary 28.35 would understate the weight by almost 9 percent. For everything else — food, body weight, luggage, parcels — the ounce in the formula is always the avoirdupois ounce, 28.349523125 grams. The troy system is a historical leftover from the medieval French town of Troyes, and it survives today only in bullion and gemstone trading. If a recipe, a shipping label, or a scale says 'oz' with no qualifier, it means the ordinary ounce.

Fluid Ounces Are Not Weight Ounces

The most common ounces-to-grams mistake has nothing to do with the formula: it is converting fluid ounces with it. A fluid ounce measures volume, not weight, and the two only line up for water. One US fluid ounce is 29.5735 millilitres, and since water weighs 1 gram per millilitre, 1 fluid ounce of water weighs about 29.57 grams — close to, but not the same as, 1 weight ounce at 28.35 grams. Eight fluid ounces of water weighs 236.59 grams, while 8 weight ounces is 226.80 grams: a gap of nearly 10 grams. For anything denser than water the gap grows fast. Eight fluid ounces of honey weighs about 336 grams, because honey is roughly 1.42 times as dense as water. Eight fluid ounces of milk weighs about 244 grams. Eight fluid ounces of olive oil weighs about 216 grams, because oil is lighter than water. So before you multiply by 28.349523125, check the label: if it says 'fl oz', you are looking at a volume and need the density of the liquid before any gram figure makes sense. Nutrition labels are the usual trap — a serving listed as '1 oz (28 g)' is a weight ounce, while a drink listed as '8 fl oz' is a volume. For the volume side of the same kitchen math, our fluid ounces to liters converter handles the millilitre step.

Grams to Ounces: The Reverse Trip

Going the other way, divide grams by 28.349523125: ounces = grams ÷ 28.349523125. So 100 grams is 100 ÷ 28.349523125 = 3.52740 ounces, or about 3.5 ounces. Two hundred and fifty grams is 8.82 ounces. Five hundred grams is 17.64 ounces. One kilogram (1,000 grams) is 35.27 ounces. The quick mental version is to divide by 28.35: 100 ÷ 28.35 is about 3.5, and 1,000 ÷ 28.35 is about 35.3, which is close enough for luggage, recipes, and gym weights. The cleanest anchor for the reverse direction is that 28.35 grams is one ounce, 56.70 grams is two ounces, and 226.80 grams is eight ounces — the same table as above, read backwards. One caution: never convert ounces to grams by going through pounds in your head (ounces to pounds, then pounds to grams) unless you keep the full factors, because rounding the pound step to 0.06 first throws away nearly 4 percent before you even start. Our ounces to pounds converter does the two-step version properly when you need pounds rather than grams.

Ounces to Grams in the Kitchen

Baking is where the ounces-to-grams formula earns its keep, because American recipes are written in ounces while the rest of the world bakes in grams. One ounce of butter is 28.35 grams, exactly two tablespoons, because one tablespoon of butter is 14.17 grams — so a recipe calling for 4 ounces of butter wants 113.40 grams, or eight tablespoons, which is one stick. One ounce of baking chocolate is 28.35 grams, exactly one square of a standard baking-chocolate bar. One ounce of all-purpose flour is 28.35 grams, about a quarter of a cup at the standard 120 grams per cup — so a recipe calling for an ounce of flour wants just under a quarter cup, spooned and levelled, not scooped. One ounce of granulated sugar is 28.35 grams, about two tablespoons at 200 grams per cup. One ounce of grated cheese is 28.35 grams, roughly a matchbox-sized piece. The practical payoff is accuracy: a cup of flour can vary by 20 percent depending on how it is scooped, while 28.35 grams is 28.35 grams every time. If your recipe says '8 oz chocolate' and your scale reads grams, weigh out 227 grams and you are done — and if it says '4 oz butter', weigh 113 grams and cut off half a stick. For the cup-to-gram side of the same kitchen math, our guide to converting cups to grams for flour works through the reverse direction cup by cup.

Common Mistakes When Converting Ounces to Grams

Five mistakes catch almost everyone at first. Converting fluid ounces with the weight formula: a fluid ounce measures volume, and 8 fluid ounces of honey weighs about 336 grams, not 226.80 — the ounces-to-grams formula is about weight, not volume, so never convert a fluid-ounce figure with it. Rounding too early: multiplying by 28 and then multiplying again by several ounces compounds the error — for a 50-ounce bag, use 28.349523125 and round only at the end. Using the troy ounce: 31.10 grams instead of 28.35, a 9 percent error, and the only place it applies is precious metals. Mixing up the direction: ounces to grams is a multiplication (the number gets bigger — 8 ounces becomes 226.80 grams), and grams to ounces is a division (the number gets smaller — 226.80 grams becomes 8 ounces). If your answer moves the wrong way, you divided when you should have multiplied. Confusing the ounce with the fluid ounce on labels: a serving listed as '1 oz (28 g)' is a weight ounce, and a drink listed as '8 fl oz' is a volume — the two numbers live on different labels for a reason. One habit prevents all five: sanity-check against the anchors — one ounce is 28.35 grams, eight ounces is 226.80 grams, sixteen ounces is 453.59 grams — and if your answer is far from any of those, recheck which ounce and which operation you used.

Quick Answers

How much is 1 oz in grams? 28.349523125 grams — 28.35 rounded to two decimals, or 28 for rough kitchen math. What is the formula to convert ounces to grams? Grams = ounces × 28.349523125. How many grams is 8 oz? 226.80 grams. How many grams is 2 oz? 56.70 grams. How many grams is 4 oz? 113.40 grams. How many grams is 16 oz? 453.59 grams — exactly one pound. How do I convert oz to grams? Multiply the oz figure by 28.349523125 — 'oz' is just the abbreviation for ounces. Is 1 oz 28 grams or 28.35 grams? Exactly 28.349523125 grams; 28.35 is the rounded shortcut, accurate to 0.002%, while 28 is a rough shortcut off by 1.2%. How many grams in a troy ounce? 31.1034768 grams — used only for gold, silver and gemstones. Is an ounce the same as a fluid ounce? No — an ounce is a weight (28.35 grams) and a fluid ounce is a volume (29.57 millilitres); only water makes the two numbers nearly equal.