Cups to Grams Converter

What this does

So you are following a recipe, it says one cup of flour, and your scale only speaks grams. This converter sorts that out. Type in the number of cups, tell it which ingredient you are measuring, pick your cup size, and it gives you the weight in grams, or in milligrams or kilograms if you prefer. The ingredient part matters more than you might think, and that is really the whole trick to this tool.

How to use it

1. Enter the number of cups.
2. Choose the ingredient from the list, water, flour, the various sugars, butter, honey, and so on.
3. Pick your cup size, US Legal (240 ml) or Imperial (284 ml).
4. Choose the unit you want back, grams, milligrams, or kilograms, then press Calculate.

Pick the ingredient honestly. A cup of honey and a cup of cocoa powder are worlds apart on the scale.

Why the ingredient matters

Here is the thing a lot of converters quietly get wrong. A cup is a measure of volume, the space something fills, while a gram is a measure of weight. To get from one to the other, you need to know how heavy the ingredient is for its size, which is its density. And ingredients vary wildly.

A cup of water weighs about 240 grams. A cup of flour, for the very same space, is much lighter, because flour is full of air. A cup of honey is heavier than both, because it is dense and sticky. That is why the tool asks you to choose the ingredient first: it swaps in the right density before it does the sum.

Flour deserves a special mention, because it is the least consistent ingredient of all. Depending on the brand, the humidity in your kitchen, and above all how you scoop it, a cup of all purpose flour can land anywhere from about 120 grams to 140 grams or more. Pack it down and it climbs higher still. This is exactly why serious bakers weigh their flour instead of scooping it, and why any cup to gram figure for flour is best treated as a sensible guide rather than a hard fact. When precision really matters, as in bread or pastry, reach for the scale.

Which cup do you mean?

You might be surprised that the tool asks which cup you mean. Is a cup not just a cup? Not quite.

The tool gives you two. The US Legal cup is 240 millilitres, the official cup used on United States nutrition labels. The Imperial cup is 284 millilitres, the older British cup you will meet in vintage UK recipes. Those extra millilitres add up across several cups, so picking the right one keeps your weights honest.

For what it is worth, two other cups float around as well. The US customary cup used in most American recipes is about 237 millilitres, a hair under the legal cup, and the modern metric cup used across the UK, Australia, and Canada is 250 millilitres. They are all close, but not identical, which is half the reason cup measurements cause so much confusion. When in doubt, match the cup to wherever your recipe came from.

How the conversion works

There is no mystery under the hood. The tool takes your cups, multiplies by the size of the cup in millilitres to get the volume, then multiplies by the ingredient's density to get the weight. In plain form:

grams = cups × cup size in ml × ingredient density

Density here is simply grams per millilitre, where water sits at 1. So one cup of water in a US Legal cup is 1 × 240 × 1, which is 240 grams. Swap in something denser like honey and that same single cup climbs to around 336 grams. Want milligrams or kilograms instead? The tool just scales the grams up or down for you.

Questions people ask

References

1. King Arthur Baking. Ingredient Weight Chart. https://www.kingarthurbaking.com/learn/ingredient-weight-chart
2. U.S. Food and Drug Administration. Guidance for Industry: Guidelines for Determining Metric Equivalents of Household Measures. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-guidelines-determining-metric-equivalents-household-measures