What the conversion actually is

The avoirdupois ounce, the one on a kitchen scale and a bag of flour, is defined as exactly 28.349523125 grams. That is a legal definition rather than a measurement, so it carries no error at all. To go from grams to ounces you divide by 28.349523125. To go back you multiply by the same number.

Most people round it to 28.35 and get along fine. The error from that rounding is about 0.00001 grams per ounce, which is roughly a millionth of a gram at the scale a home cook works at. Round it. Nobody will notice.

There is a second ounce, and it trips people up in a different way. The troy ounce, used for precious metals, weighs 31.1034768 grams. Nothing in a recipe uses troy ounces, so if a number looks off by about 9 percent against your expectation, check which ounce the source meant.

The three numbers worth memorising

28.35 grams to the ounce. 454 grams to the pound. 100 grams is 3.53 ounces. Those three cover almost every recipe conversion you will meet in a kitchen, and you can derive the rest with a division.

A pound is 16 ounces, so 453.59237 grams, and a kilogram is 2.20462 pounds. A 1 kg bag of flour is 35.27 ounces, which is a little over two of the 16 ounce bags sold in the US.

Fluid ounces are a different animal

A fluid ounce is a volume. An ounce is a mass. They share four letters and nothing else.

One US fluid ounce is exactly 29.5735295625 millilitres. One US cup is 8 fluid ounces, or 236.5882 millilitres. Those figures never change, whatever you pour into the cup. Water, oil, honey and vinegar all fill 8 fluid ounces of space.

But their weights differ. A cup of water weighs 236.6 grams. A cup of vegetable oil weighs 218 grams, because oil is lighter than water. A cup of honey weighs 340 grams. Same 8 fluid ounces, three different masses.

So a fluid ounce converts to grams only if you name the substance. Water at room temperature is close to 29.57 grams per fluid ounce, which is why the two get confused. Oil is about 27.25 grams. Honey is about 42.5 grams. If a recipe says 8 ounces of honey by volume, that is a very different amount of honey from 8 ounces on a scale.

Volume	Fluid oz	Millilitres	Water, g	Oil, g	Honey, g
1 tbsp	0.5	14.79	14.8	13.6	21.3
1 fl oz	1	29.57	29.6	27.3	42.5
1/4 cup	2	59.15	59.1	54.5	85
1/2 cup	4	118.29	118.3	109	170
1 cup	8	236.59	236.6	218	340
1 pint	16	473.18	473.2	436	680

Note the water column. It is the reason the confusion exists at all. For water, and only for water, a fluid ounce and an ounce of weight are within a whisker of each other. Everything else in a kitchen breaks that coincidence.

The UK adds a wrinkle. An imperial fluid ounce is 28.4131 millilitres, smaller than the US fluid ounce, yet an imperial cup is 284.13 millilitres because it holds ten imperial fluid ounces. Older British recipes using fluid ounces will be a few percent off if you convert them with US figures.

Common baking amounts in grams and ounces

These are the numbers people search for most often. Every ounce figure is the gram figure divided by 28.349523125 and rounded to two places.

Grams	Ounces	Common use	Ounces	Grams
5 g	0.18	One teaspoon of salt	0.25	7.09
7 g	0.25	One sachet of yeast	0.5	14.17
14 g	0.49	One tablespoon of butter	1	28.35
15 g	0.53	One tablespoon of sugar	1.5	42.52
28 g	0.99	One square of chocolate	2	56.70
30 g	1.06	Two tablespoons of flour	2.5	70.87
50 g	1.76	A small handful of nuts	3	85.05
57 g	2.01	Half a stick of butter	3.5	99.22
75 g	2.65	Three quarters of a stick	4	113.40
85 g	3.00	One cup of shredded coconut	4.5	127.57
100 g	3.53	Most of a cup of flour	5	141.75
113 g	3.99	One stick of butter	6	170.10
120 g	4.23	One cup of all-purpose flour	7	198.45
125 g	4.41	One cup of flour, USDA figure	8	226.80
150 g	5.29	One cup of cornmeal	9	255.15
170 g	6.00	One cup of chocolate chips	10	283.50
200 g	7.05	One cup of granulated sugar	12	340.19
227 g	8.01	Two sticks of butter	14	396.89
250 g	8.82	One cup of milk plus a splash	16	453.59
300 g	10.58	A generous cup of honey	20	566.99
340 g	11.99	One cup of honey	24	680.39
454 g	16.01	One pound of butter	32	907.18
500 g	17.64	A half kilo of flour	35	992.23
1000 g	35.27	One kilo of flour	48	1360.78

The middle column reads both ways, which is why the table is laid out as a mirror. Start at any row and read left for grams to ounces, right for ounces to grams.

One cup of each ingredient, in grams and ounces

Weight per cup differs by ingredient, and these densities drive every other number on this site. Sort order runs lightest to heaviest.

Ingredient	1 cup, g	1 cup, oz	1/2 cup, oz	1/4 cup, oz
Shredded Coconut	85	3.00	1.50	0.75
Cocoa Powder	86	3.03	1.52	0.76
Rolled Oats	90	3.17	1.59	0.79
Almonds (sliced)	92	3.25	1.62	0.81
Almond Flour	96	3.39	1.69	0.85
Cake Flour	114	4.02	2.01	1.01
All-Purpose Flour	120	4.23	2.12	1.06
Whole Wheat Flour	120	4.23	2.12	1.06
Powdered Sugar	120	4.23	2.12	1.06
Coconut Flour	120	4.23	2.12	1.06
Walnuts (chopped)	120	4.23	2.12	1.06
Bread Flour	127	4.48	2.24	1.12
Cornstarch	128	4.52	2.26	1.13
Cornmeal	150	5.29	2.65	1.32
Raisins	165	5.82	2.91	1.46
Semolina	167	5.89	2.95	1.47
Chocolate Chips	170	6.00	3.00	1.50
White Rice (uncooked)	185	6.53	3.26	1.63
Brown Rice (uncooked)	190	6.70	3.35	1.68
Granulated Sugar	200	7.05	3.53	1.76
Olive Oil	216	7.62	3.81	1.90
Vegetable Oil	218	7.69	3.84	1.92
Brown Sugar (packed)	220	7.76	3.88	1.94
Butter	227	8.01	4.00	2.00
Sour Cream	230	8.11	4.06	2.03
Baking Powder	230	8.11	4.06	2.03
Cream Cheese	232	8.18	4.09	2.05
Water	237	8.36	4.18	2.09
Heavy Cream	238	8.40	4.20	2.10
Milk	244	8.61	4.30	2.15
Yogurt	245	8.64	4.32	2.16
Peanut Butter	258	9.10	4.55	2.28
Table Salt	288	10.16	5.08	2.54
Maple Syrup	312	11.01	5.50	2.75
Honey	340	11.99	6.00	3.00

Thirty five ingredients, and a cup of one weighs 3.00 ounces while a cup of another weighs 11.99. That spread is the entire argument for weighing your ingredients instead of scooping them.

Fraction equivalents and rounded rules of thumb

Scales display decimals and recipes use fractions, so a small translation table helps. These are the ounce figures you will actually see on a digital display, with the fraction a cook would recognise.

Grams	Exact ounces	Rounded	Nearest fraction
1 g	0.035	0.04	A pinch, near enough
3 g	0.106	0.11	Under 1/8 ounce
4 g	0.141	0.14	About 1/8 ounce
7 g	0.247	0.25	1/4 ounce
10 g	0.353	0.35	Just over 1/3 ounce
14 g	0.494	0.49	1/2 ounce
20 g	0.705	0.71	7/10 ounce
25 g	0.882	0.88	About 7/8 ounce
28 g	0.988	0.99	1 ounce
35 g	1.235	1.23	1 1/4 ounces
42 g	1.482	1.48	1 1/2 ounces
50 g	1.764	1.76	1 3/4 ounces
57 g	2.011	2.01	2 ounces
70 g	2.469	2.47	2 1/2 ounces
85 g	2.998	3.00	3 ounces
100 g	3.527	3.53	3 1/2 ounces
113 g	3.986	3.99	4 ounces, one stick of butter
142 g	5.009	5.01	5 ounces
170 g	5.996	6.00	6 ounces
200 g	7.055	7.05	7 ounces
227 g	8.007	8.01	8 ounces, half a pound
250 g	8.818	8.82	Just under 9 ounces
340 g	11.993	11.99	12 ounces
454 g	16.014	16.01	1 pound
500 g	17.637	17.64	1 pound 1.6 ounces
1000 g	35.274	35.27	2 pounds 3.3 ounces

Two shortcuts that hold up

Divide grams by 30 to get a rough ounce count. It undershoots by about 5 percent, which is fine for eyeballing a portion and not fine for a cake.

Or multiply ounces by 28 and add 1 percent. For 8 ounces that gives 226.8 grams against the true 226.80, so it lands exactly at the precision a kitchen scale offers.

Why the numbers move around in practice

The conversion is exact. The measurement is not. A recipe written in grams can still produce a cake that behaves differently from one baker to the next, and the reason is upstream of the arithmetic.

Flour settles. It compacts in the bag during shipping and storage, and a scoop pressed into a settled bag can weigh 20 percent more than the same scoop used gently. This is the single largest source of error in home baking, and it dwarfs any rounding you do at the conversion step.

The published densities disagree, too. This site uses 120 grams per cup for all-purpose flour, which is 4.23 ounces. USDA FoodData Central lists 125 grams per cup, or 4.41 ounces. Food Standards Australia New Zealand publishes a figure nearer 128 grams. Each of these is an honest measurement of the same flour, taken with a different filling technique.

Scale accuracy is a smaller factor but not zero. A cheap kitchen scale reading to 1 gram has an error of about half a gram either way, which at 100 grams is half a percent. That is acceptable. If your scale reads to 5 grams, the error climbs to 5 percent, which is enough to matter in a bread dough.

Temperature moves things a little as well. A cup of cold honey weighs a bit more than a cup of warm honey because it is denser when cold. The gap is real but small compared with how much honey sticks to the cup, which is the error that actually ruins the batch.

Where the small errors stack up

If your flour is over-packed by 15 percent and your scale is off by 2 percent high, a recipe calling for 500 grams gets roughly 587 grams of flour. In a lean bread dough that is enough to make the loaf dense and dry, and the recipe takes all the blame.

The fix costs nothing. A stir through the flour with a fork, then a gentle spooning into the measuring cup, gets you close. A scale gets you exact, and it is the habit worth building.

Questions cooks actually ask

How many grams are in an ounce?: Exactly 28.349523125 grams. Most cooks use 28.35 and never notice the difference, since the rounding error is about a millionth of a gram per ounce.
Is 100 grams the same as 4 ounces?: Not quite. 100 grams is 3.53 ounces. Four ounces is 113.4 grams, so the two differ by about 13 percent. They get used interchangeably in casual conversation, and that is where small recipe errors come from.
Why does my recipe say fluid ounces when I have a scale?: Because the writer measured in a cup. One fluid ounce is 29.5735 millilitres, a volume, so it only becomes grams when you know the ingredient. For water you can treat them as near enough, and for anything else you cannot.
How do I convert grams to ounces without a calculator?: Divide by 30 for a rough figure, or divide by 28.35 for an accurate one. Going the other way, double the ounces and add 10 percent of that, then add a bit more. Eight ounces becomes 16, plus 1.6, plus a nudge, which lands near 227 grams.
Does this work for liquids like milk and oil?: Yes, if you weigh them. 100 grams of milk is 3.53 ounces the same as anything else, because the conversion is mass to mass. It only changes if you are converting from a volume in cups, and then the density of the liquid is the deciding factor.
Which ounce does a US kitchen scale use?: The avoirdupois ounce, at 28.3495 grams, the same one a bag of flour is labelled in. Troy ounces, at 31.1035 grams, appear only in precious metals and never in a recipe.

Where these numbers come from

The ounce is defined as exactly 28.349523125 grams, and the US fluid ounce as exactly 29.5735295625 millilitres derived from the 236.5882365 millilitre US customary cup divided by eight. Those are definitions rather than measurements, so they carry no error at all.

The per ingredient cup weights come from the vetted density set this site maintains, set out in full with sourcing and method on the cups to grams page. Every ounce figure in the tables above is that gram figure divided by 28.349523125, computed in code rather than typed by hand, so the tables and the tool cannot disagree with each other.

Flour is the one figure with a genuine caveat, and the sources disagree in public. This site uses 120 grams per cup for all-purpose flour, USDA lists 125, and the Australian and New Zealand food authority publishes a density nearer 128. The spread comes entirely from how the cup was filled. Weigh it when the recipe is fussy about structure.

Related converters

These use the same density set and the same ounce definition.

Grams to Ounces.

Grams to ounces converter