You are halfway through a recipe when it happens: the instructions call for 250 grams of flour, but your only measuring tools are a set of cups. Or the reverse happens, and a beloved family recipe lists "two cups of sugar" while you are cooking in a kitchen that only speaks metric. Cooking is one of the few places where the metric and US customary systems collide every day, and getting the translation wrong can flatten a cake or turn a sauce into soup. This guide walks you through the conversions that matter most at the stove, and the one honest caveat that careful bakers never ignore.
Volume vs. Weight: Why Cooking Measurements Get Confusing
Most kitchen confusion comes down to a single idea: some measurements describe volume (how much space an ingredient takes up) and others describe weight (how much it actually weighs). A cup, a tablespoon, a milliliter, and a fluid ounce all measure volume. A gram, an ounce, and a pound measure weight.
This matters because volume and weight are not interchangeable across ingredients. One cup of feathers and one cup of lead fill the same space, but they weigh wildly different amounts. Flour and sugar are less dramatic, but the same principle applies: a cup of flour weighs far less than a cup of honey. That is why you cannot simply memorize "one cup equals X grams" and apply it to everything. The gram value depends entirely on what you are measuring.
For conversions outside the kitchen, such as length, distance, speed, and area, our general unit conversion guide covers the wider picture. Here we stay focused on food.
US Cups Are Not Metric Cups
Here is a detail that trips up even experienced cooks: a "cup" is not a single universal amount. Depending on where a recipe was written, it can mean several different volumes:
- 1 US cup = 236.6 mL (the standard in most American recipes)
- 1 US "legal" cup = 240 mL (used on nutrition labels, and the value US recipes often round to)
- 1 metric cup = 250 mL (standard in Australia, New Zealand, and much of Europe)
- 1 Japanese cup = 200 mL
- 1 old UK imperial cup = about 284 mL (rare today, since modern British recipes use grams and milliliters)
In everyday cooking, the difference between a 236.6 mL US cup and a 250 mL metric cup, roughly 5 percent, is usually harmless for soups and stews. In baking, where ratios matter, that 5 percent can be the difference between a tender crumb and a dense one. When a recipe does not specify, a good rule of thumb is to assume US cups if it also uses Fahrenheit and pounds, and metric cups if it uses Celsius and grams.
Converting Common Baking Ingredients
Because the gram value of a cup changes from ingredient to ingredient, the only reliable approach is to learn a handful of the most common ones. The values below are widely accepted approximations, not exact constants, and they assume US cups. Treat them as solid starting points.
Flour
All-purpose (plain) flour is the classic troublemaker because it compresses. A cup of flour scooped straight from the bag can weigh noticeably more than a cup spooned in gently and leveled off. As an approximate, widely used value, 1 US cup of all-purpose flour weighs about 120 to 125 grams. Bread flour is similar. If your recipe came from a professional bakery, it almost certainly means the lower, spooned-and-leveled figure.
Sugar
Granulated white sugar is denser and far more consistent than flour. 1 US cup of granulated sugar weighs approximately 200 grams. Packed brown sugar is heavier because you press it down: about 220 grams per cup. Powdered sugar (also called confectioners or icing sugar) is light and airy at roughly 120 grams per cup. Because sugar does not compress the way flour does, these figures are more dependable.
Butter
Butter is easy once you learn the anchor. In the US, butter is sold in sticks. 1 stick = 1/2 cup = 4 ounces = about 113 grams. So 1 full cup of butter = 2 sticks = 8 ounces = approximately 227 grams. Many US butter wrappers even print tablespoon markings: 1 stick holds 8 tablespoons, which makes cutting off "2 tablespoons of butter" a matter of following the lines on the paper.
Liquids: Cups, Milliliters, and Fluid Ounces
Liquids are the friendliest ingredients to convert because water-based liquids weigh almost exactly what their volume suggests. A few reference points cover most recipes:
- 1 US cup of water is about 237 mL and weighs about 237 grams
- 1 US cup is commonly rounded to 240 mL in recipes for convenience
- 1 liter is a little over 4 US cups
- 1 US fluid ounce is about 29.6 mL
Milk, stock, and most thin liquids are close enough to water that you can treat them the same way for home cooking. Thick liquids are the exception: honey weighs about 340 grams per cup because it is far denser than water, so never assume a cup of syrup weighs the same as a cup of milk.
Ounces vs. Fluid Ounces: A Trap Worth Knowing
This is one of the most common cooking-conversion mistakes, so it earns its own section. An ounce (oz) is a unit of weight equal to about 28.35 grams. A fluid ounce (fl oz) is a unit of volume equal to about 29.57 milliliters. They share a name and land close together in number, but they measure completely different things.
The overlap is mostly harmless with water, because 1 fluid ounce of water happens to weigh almost exactly 1 ounce. But 1 fluid ounce of flour does not weigh 1 ounce, and 1 fluid ounce of honey weighs considerably more. When a recipe says "8 oz of chocolate," it means weight; when it says "8 fl oz of milk," it means volume. Reading the label carefully saves a lot of ruined batches.
Teaspoons, Tablespoons, and the Australian Exception
Small volumes are where a lot of seasoning goes right or wrong. The core relationships are worth committing to memory:
- 1 US teaspoon is about 5 mL
- 1 US tablespoon is about 15 mL, which equals 3 teaspoons
- 1 US cup = 16 tablespoons = 48 teaspoons
These small measures are nearly identical across the US, UK, and metric systems, with one famous exception: the Australian tablespoon is 20 mL, or 4 teaspoons, not 3. If you follow an Australian recipe with a US tablespoon, you will come up slightly short on every spoonful. For most dishes this is minor, but for baking soda, baking powder, and strong spices it can genuinely change the result.
Oven Temperatures: Fahrenheit, Celsius, and Gas Marks
Oven dials are the other place where US and metric recipes diverge. The exact conversion between Fahrenheit and Celsius uses the formula C = (F - 32) x 5/9, but for ovens you rarely need that precision, because ovens themselves are not that precise. Older British recipes add a third scale, the gas mark. Here are the everyday reference points, rounded to the numbers ovens actually use:
- 275 F = 140 C = gas mark 1 (very low, slow cooking)
- 300 F = 150 C = gas mark 2
- 325 F = 160 C = gas mark 3
- 350 F = 180 C = gas mark 4 (the standard baking temperature)
- 375 F = 190 C = gas mark 5
- 400 F = 200 C = gas mark 6 (hot, for roasting)
- 425 F = 220 C = gas mark 7
- 450 F = 230 C = gas mark 8 (very hot)
- 475 F = 240 C = gas mark 9
One extra adjustment matters: if you have a fan-forced or convection oven, reduce the temperature by about 15 C (roughly 25 F) from what a conventional recipe lists, because the moving air cooks food faster.
The Honest Truth: Weight Beats Volume for Baking
Here is the caveat every serious baker will share, and the one this guide will not hide: for baking, weighing your ingredients in grams is more reliable than measuring by volume, and it is not a close contest.
The reason goes straight back to the volume-versus-weight distinction. A cup of flour can vary by a fifth or more depending on whether it was scooped, spooned, sifted, or packed, and on the humidity and how settled the bag is. Every "1 cup equals about 120 grams" figure in this article is an approximation of an average. It is a real, honest average, but an average nonetheless. Cooking such as soups, stews, and sauces tolerates this variation happily. Baking, which is essentially edible chemistry, does not: bread, cakes, and pastry depend on precise ratios of flour to liquid to fat.
If you bake regularly, a cheap digital kitchen scale is the single best upgrade you can make. Weigh in grams and you sidestep the cup-conversion problem entirely. When a recipe gives only cups, use the approximate gram values here as a starting point, and trust weight over volume whenever both are offered.
A Quick Cooking Conversion Cheat Sheet
Keep these approximate values within reach:
- 1 US cup all-purpose flour = about 120 to 125 g
- 1 US cup granulated sugar = about 200 g
- 1 US cup packed brown sugar = about 220 g
- 1 US cup butter = 2 sticks = 8 oz = about 227 g
- 1 US cup water or milk = about 237 mL (240 mL rounded)
- 1 US cup = 236.6 mL = 8 fl oz = 16 tablespoons
- 1 tablespoon = 15 mL = 3 teaspoons; 1 teaspoon = 5 mL
- 1 ounce (weight) = 28.35 g; 1 fluid ounce (volume) = 29.57 mL
- 350 F = 180 C = gas mark 4 (standard baking)
Remember that the gram values for dry ingredients are approximate and depend on the ingredient, so when precision matters, reach for a scale.
Convert Cooking Measurements Instantly
You do not have to keep a chart taped to your cabinet. Our free Unit Converter handles volume, weight, and temperature in one place, so you can turn cups into milliliters, ounces into grams, or Fahrenheit into Celsius the moment a recipe demands it. It runs entirely in your browser, needs no sign-up, and gives instant results. Bookmark it, and let the measuring cups and the kitchen scale settle their differences while you get on with cooking.