A recipe says 200 grams of butter. A parcel label says 8 ounces. A gym scale reads 70 kilograms and a friend asks what that is in pounds. Grams and ounces meet in the kitchen, at the post office and on the bathroom scales — and the conversion is a division or multiplication, once you know which way round it goes.
The Unit Converter does the maths in seconds, but the method is worth knowing by hand: recipes do not wait for a calculator, and a result you can sense-check is a result you can trust. This article works through the factor, the direction of the calculation, worked examples, a mental shortcut and the common mistakes.
The one number to remember: 28.3495
Every grams-to-ounces conversion rests on one fact: 1 ounce is 28.3495 grams. That is the avoirdupois ounce, the everyday ounce used for food, parcels and body weight in the United States and in older British recipes. It is the ounce the Unit Converter uses, and the ounce this article uses throughout.
It comes from the pound: one avoirdupois pound is 453.59237 g, and a pound is 16 oz, so one ounce is 453.59237 ÷ 16 = 28.349523125 g, rounded to the standard 28.3495 g.
Two companion facts: 1 pound is 453.592 g (16 × 28.3495), and 1 kilogram is 2.20462 lb. Between the three — 28.3495, 16 and 2.20462 — you can move between grams, ounces, pounds and kilograms without looking anything up.
Which way round: divide or multiply?
This is where most people go wrong, so it deserves a rule you can say in one breath: grams to ounces, divide; ounces to grams, multiply. Grams are smaller units than ounces, so the same weight is a bigger number in grams and a smaller number in ounces. To the bigger unit, divide; to the smaller unit, multiply.
Grams to ounces: ounces = grams ÷ 28.3495. Ounces to grams: grams = ounces × 28.3495.
Before you trust any answer, sense-check it: 100 g ÷ 28.3495 = 3.527399 oz looks right, because the ounce number is much smaller than the gram number. Multiply instead and you get 2834.95 oz for one chocolate bar — absurd on its face.
Worked examples: the kitchen
100 g chocolate bar. 100 ÷ 28.3495 = 3.527399 oz. A standard 100 g bar of chocolate weighs about 3.53 oz — the conversion that turns up most often, because European recipes are written in grams and American ones in ounces.
200 g of butter. 200 ÷ 28.3495 = 7.054798 oz, just under half a pound (8 oz). One stick of butter is 4 oz (113.398 g), so 200 g is about one and three-quarter sticks.
250 g of flour. 250 ÷ 28.3495 = 8.818498 oz, a little over half a pound. If a recipe calls for 8 oz and you only have a metric scale, weigh out 226.796 g (8 × 28.3495).
500 g bag of sugar. 500 ÷ 28.3495 = 17.636995 oz — 1 lb and 1.64 oz. A recipe asking for a pound of sugar needs 453.592 g, so a 500 g bag holds slightly more than you need.
1 kilogram of flour. 1000 ÷ 28.3495 = 35.273991 oz, or 2.20462 lb — just over two pounds. Above a kilogram, use pounds instead: kilograms × 2.20462.
Going the other way: 12 oz of chocolate chips. 12 × 28.3495 = 340.194 g. A 12 oz bag of chocolate chips needs about 340 g on a metric scale, and 4 oz (one stick of butter) is 113.398 g — which is why charts list 113 g as a quarter pound.
Worked examples: parcels and luggage
A 500 g parcel. The same 500 ÷ 28.3495 = 17.636995 oz applies, and postage is charged by weight bands: 17.64 oz sits just over the 1 lb mark, so a 500 g parcel falls into the next band up — convert before you book, not at the counter.
A 23 kg suitcase. 23 kg is the standard checked-baggage limit, and 23 × 2.20462 = 50.70626 lb — just over the 50 lb limit many US airlines set. A bag packed to 23 kg is 0.71 lb over; packing to 22 kg (48.50164 lb) leaves a safe margin.
A 70 kg body weight. 70 × 2.20462 = 154.3234 lb, so 70 kg is about 154.32 lb. The other way, 150 lb ÷ 2.20462 = 68.038936 kg — just over 68 kg.
The mental shortcut — and why it is only approximate
Dividing by 28.3495 in your head is nobody’s idea of fun, so here is the shortcut: treat an ounce as roughly 28 grams. Divide the grams by 28 instead, and you get an answer close enough for cooking and rough weighing.
For 100 g, the shortcut gives 100 ÷ 28 = 3.571429 oz against the true 3.527399 oz — about 0.044 oz too high. For 500 g it gives 17.857143 oz against 17.636995 oz, about 0.22 oz too high. The shortcut always overshoots, because 28 is smaller than 28.3495.
Fine for a recipe, where a gram or two of flour will not ruin a cake. Not good enough where the number is contractual: a 1.2% error on a 10 kg parcel is 120 g, enough to push it into the next price band. Use the shortcut for the kitchen; use the real factor, or the Unit Converter, for anything you pay for.
Common mistakes
- Dividing the wrong way round. The most common error: multiplying grams by 28.3495 instead of dividing. 100 g × 28.3495 = 2834.95 — the weight of a small child, not a chocolate bar. If your answer is bigger than the number you started with, you multiplied by mistake: grams to ounces always makes the number smaller.
- Using the troy ounce. A troy ounce is 31.1035 g, heavier than the everyday ounce by 2.754 g, and used only for precious metals. A 100 g bar of gold is 100 ÷ 31.1035 = 3.215072 troy ounces, not 3.527399 oz. If the thing being weighed is not a precious metal, the troy ounce does not apply.
- Confusing ounces with fluid ounces. An ounce measures weight; a fluid ounce measures volume, and 1 US fluid ounce is 29.5735 ml. Eight fluid ounces of water happens to weigh about 8 oz, but 8 fl oz of honey weighs much more, because honey is denser than water. Convert weight to weight and volume to volume — never swap the two.
- Forgetting that a pound is 16 ounces, not 10. Imperial weight is not decimal: 8 oz is half a pound, not 0.8 of a pound. The slip shows up when 500 g becomes 1.1 lb and gets read as 1 pound 1 ounce, when 1.1 lb is actually 1 lb and 1.6 oz. 17.636995 oz is 1 lb 1.64 oz, not 1.1 lb in any useful sense.
- Rounding too early. Converting 100 g gives 3.527399 oz; rounding to 3.5 oz and converting back gives 3.5 × 28.3495 = 99.22325 g, not 100 g. The error compounds if the result feeds another calculation. Keep the full result while you work; round only at the end.
Related tools
For the exact answer on any weight, the Unit Converter converts grams, ounces, pounds and kilograms instantly — pick Weight, enter the value, and the result updates as you type. It also covers volume, length, time and torque. It is free, runs entirely in your browser, and needs no sign-in. For all of ToolZana’s free tools, start at the ToolZana home page.
The short version
One ounce is 28.3495 grams. Grams to ounces, divide by 28.3495: 100 g is 3.527399 oz, 500 g is 17.636995 oz, 1000 g is 35.273991 oz. Ounces to grams, multiply: 1 oz is 28.3495 g, 16 oz is 453.592 g — exactly one pound. A kilogram is 2.20462 lb, so 5 kg is 11.0231 lb and a 23 kg suitcase is 50.70626 lb. In your head, divide grams by 28 for an answer about 1.2% high — fine for cooking, not for postage. Remember the traps: the troy ounce (31.1035 g) is for precious metals only, fluid ounces measure volume, a pound is 16 ounces, and you round at the end, never in the middle.
Frequently Asked Questions
How many ounces is 100 grams?
100 grams is 3.527399 ounces. Divide by 28.3495, because 1 ounce is 28.3495 grams: 100 ÷ 28.3495 = 3.527399 oz, or about 3.53 oz rounded. A 100 g chocolate bar weighs about three and a half ounces, and the same division works for any weight — 200 g is 7.054798 oz and 50 g is 1.7637 oz.
How many grams are in 8 ounces?
There are 226.796 grams in 8 ounces. Multiply by 28.3495: 8 × 28.3495 = 226.796 g. Eight ounces is half a pound, and half of 453.592 g (one pound) is 226.796 g — a useful cross-check. Other handy values: 4 oz is 113.398 g, 2 oz is 56.699 g, 12 oz is 340.194 g.
How do I convert grams to ounces in my head?
Divide the grams by 28 instead of 28.3495. For 100 g that gives 100 ÷ 28 = 3.571429 oz against the true 3.527399 oz — about 0.044 oz too high, an error of roughly 1.2%. The shortcut always overshoots slightly, but the error stays near 1.2% at any size, so it is fine for cooking and rough weighing. For anything you pay for, use the real factor of 28.3495 or the Unit Converter.
Is an ounce of gold the same as an ounce of flour?
No. Gold is weighed in troy ounces, and one troy ounce is 31.1035 g, heavier than the everyday avoirdupois ounce of 28.3495 g by 2.754 g. A 100 g bar of gold is 100 ÷ 31.1035 = 3.215072 troy ounces, not 3.527399 oz. Flour, parcels and body weight all use the avoirdupois ounce — mixing the two up overstates a food weight by nearly 10%.
What is the difference between ounces and fluid ounces?
An ounce measures weight and a fluid ounce measures volume — different units that happen to share a name. One ounce is 28.3495 grams, while one US fluid ounce is 29.5735 millilitres. Eight fluid ounces of water weighs about 8 oz, but 8 fl oz of honey weighs much more, because honey is denser than water. Convert weight to weight and volume to volume.
How many ounces are in a kilogram?
There are 35.273991 ounces in a kilogram: 1000 ÷ 28.3495 = 35.273991 oz, or about 35.27 oz rounded. A kilogram is also 2.20462 lb, which is the same answer in different units — 2.20462 lb × 16 oz = 35.27392 oz, matching to within rounding. For 2 kg, double it: 70.547981 oz, or 4.40924 lb.
How do I convert a 23 kg suitcase to pounds?
Multiply the kilograms by 2.20462, because 1 kg is 2.20462 lb: 23 × 2.20462 = 50.70626 lb. A 23 kg suitcase weighs just over 50 lb, which matters because many US airlines set their checked-baggage limit at 50 lb — a bag packed to exactly 23 kg is 0.71 lb over. Packing to 22 kg (48.50164 lb) leaves a safe margin.
How many grams are in a pound and a half?
There are 680.388 grams in a pound and a half: 1.5 lb × 453.592 = 680.388 g. You can reach the same number through ounces: a pound and a half is 24 oz, and 24 × 28.3495 = 680.388 g. Either route gives the same answer — a good way to check your arithmetic, since the two routes disagree only if one has an error in it.
Why is my answer slightly different from the calculator’s?
Almost always because of rounding. The exact factor is 28.349523125 g per ounce, and this article and the Unit Converter use the standard rounded factor of 28.3495 g, which changes a 100 g conversion by less than a thousandth of an ounce. Bigger differences come from rounding the result too early: 100 g to 3.5 oz and back gives 3.5 × 28.3495 = 99.22325 g, not 100 g. Keep the full result while you work and round only at the end.
What is the fastest way to convert grams to ounces?
Use the free Unit Converter. Pick the Weight category, enter the grams, and set the units to grams and ounces — the result updates as you type, shows the factor it used (1 oz = 28.3495 g), and rounds to 6 decimal places. It runs entirely in your browser, needs no sign-in, and converts straight back with the Swap button.