A 5 lb bag of all-purpose flour holds about 18.9 cups. The arithmetic is straightforward: 5 lb is 2,268 g, and one cup of all-purpose flour weighs 120 g spooned and levelled, so 2,268 divided by 120 is 18.9 cups. The figure is approximate, because a cup of flour is not a fixed weight — it depends on how you fill the cup. Spoon the flour in and level it off, and you get 120 g. Scoop the cup straight into the bag, and you can pack in 130 g or even 142 g, which would give you only about 16 cups from the same bag. The 18.9 cup figure assumes the spooned-and-levelled method, which is the standard.
Eighteen point nine cups is a lot of baking. A standard loaf of bread uses about 3 cups of flour, a batch of cookies uses 2 to 3 cups, a cake uses 2 cups. One 5 lb bag covers roughly six loaves of bread, or eight batches of cookies, or nine cakes — which is why the 5 lb bag is the standard size for home bakers. Knowing the cup count lets you plan: if you bake a loaf every weekend, a bag lasts about six weeks; if you bake daily, it lasts less than a week. It also tells you when to buy the bigger bag — a 10 lb bag holds about 37.8 cups, and it is usually cheaper per cup, but only if you will use it before the flour goes stale.
Bag of flour conversion table
The table below shows how many cups you get from fractions of a 5 lb bag, and how many cups of flour weigh how many grams. All figures use 120 g per cup, spooned and levelled.
| Amount | Cups (approx.) | Weight |
|---|---|---|
| 1/4 bag | 4.72 cups (about 4 3/4 cups) | 567 g |
| 1/2 bag | 9.45 cups (about 9 1/2 cups) | 1,134 g |
| 3/4 bag | 14.17 cups (about 14 1/8 cups) | 1,701 g |
| Full bag | 18.90 cups (about 18 7/8 cups) | 2,268 g |
| Cups | Grams (approx.) |
|---|---|
| 1 cup | 120 g |
| 2 cups | 240 g |
| 3 cups | 360 g |
| 4 cups | 480 g |
| 5 cups | 600 g |
| 10 cups | 1,200 g |
If you scoop your flour instead of spooning it, a cup can weigh 130 g or more, and the same bag will yield only about 17 cups. The spooned-and-levelled method is the standard, and it is the method the 120 g figure assumes.
Worked examples
A week of bread baking
A home baker who makes a loaf every other day uses about 3 cups of flour per loaf. One 5 lb bag holds 18.9 cups, so it covers six loaves — about twelve days of baking. Weigh the flour for each loaf instead of measuring by volume: 3 cups is 360 g, and weighing gives you a consistent loaf every time, while cup measurements vary with how you fill the cup. When the bag is down to its last few cups, check how much is left by weighing the bag — a kitchen scale tells you exactly how many grams remain, and dividing by 120 tells you how many cups that is.
A baking weekend for a school fair
A school fair needs twelve dozen cookies, which is six batches at 2 cups of flour each — 12 cups in total. One 5 lb bag holds 18.9 cups, so a single bag covers the whole fair with nearly 7 cups to spare. Measure the flour by weight for consistency across batches: 12 cups is 1,440 g, and weighing ensures every batch tastes the same. If you are also making cakes for the fair, a cake uses about 2 cups, so the spare 7 cups cover three cakes as well — one bag does the whole event.
A month of everyday cooking
A household that bakes once a week — a cake on Sunday, a batch of cookies midweek — uses about 4 cups of flour a week. One 5 lb bag holds 18.9 cups, so it lasts about four and a half weeks. Store the flour in an airtight container rather than in the bag, because the bag tears and lets in moisture and pantry moths. A large jar or a sealed tub keeps the flour fresh for up to a year, and it makes measuring easier: you can spoon flour from a wide-mouthed container without spilling it across the worktop.
How the figure is worked out
Think of the answer as a conversion, not a measurement. The package weight is a standard 5 lb (2,268 g) bag of all-purpose flour. One cup of this ingredient weighs a known number of grams, so the cups in the package are the package weight divided by the cup weight. The method matters as much as the number: a spooned and levelled cup is the standard, and a scooped cup packs in more, which is why two bakers can get different cup counts from the same bag. The cup weight used here is 120 g per cup, spooned and levelled, sourced from King Arthur Baking. Flour weight is the most disputed conversion in baking: King Arthur lists 120 g per cup spooned and levelled, while other sources quote 125 g, 130 g and up to 142 g for a scooped cup. We use the King Arthur spooned-and-levelled value as primary.
Practical guidance
Store flour in an airtight container in a cool, dry place, and it will keep for up to a year. The paper bag it comes in is not airtight, and it tears easily, so decant the flour into a jar or a sealed tub as soon as you open it. Keep it away from strong smells — flour absorbs odours, and flour stored next to onions will taste of onions. If you buy flour in bulk, freeze it for 48 hours when you bring it home: freezing kills any pantry moth eggs that may be present, and it is the simplest way to protect a large bag.
Measure flour by weight whenever you can. A cup of flour can weigh anywhere from 120 g to 142 g depending on how you fill it, and that 22 g difference is nearly a fifth of a cup — enough to make a cake dry or a loaf dense. Weighing removes the variable entirely: 120 g is 120 g, every time. If you do not have a scale, spoon the flour into the cup and level it off with a knife — never scoop the cup into the bag, because scooping packs the flour down and gives you too much. And remember the dispute: other sources quote 125 g, 130 g and even 142 g per cup, all for different filling methods. The 120 g figure is the King Arthur spooned-and-levelled standard, and it is the one this site uses consistently.
Frequently asked questions
How many cups are in a 10 lb bag of flour?
About 37.8 cups. A 10 lb bag is 4,536 g, and at 120 g per cup that divides out to 37.8 cups. It is simply double the 5 lb bag, so if you know the 5 lb figure, double it. A 10 lb bag is better value per cup, but only if you use it before the flour goes stale — about a year in an airtight container.
How many cups are in a 2 lb bag of flour?
About 7.6 cups. A 2 lb bag is 907 g, and at 120 g per cup that is 7.55 cups. Small bags are useful if you bake rarely, because a 5 lb bag may go stale before you finish it. A 2 lb bag covers two loaves of bread or three batches of cookies.
Why do different sources give different cups per bag?
Because a cup of flour is not a fixed weight. Spooned and levelled, a cup is 120 g and a 5 lb bag holds 18.9 cups. Scooped, a cup can be 130 g or 142 g, and the same bag holds only 17.4 or 16 cups. The difference is the filling method, not the flour — which is why weighing is more reliable than measuring by volume.
How long does an opened bag of flour keep?
Up to a year in an airtight container in a cool, dry place. Flour does not go off suddenly, but it does go stale and can develop an off taste, especially whole wheat flour, which contains oils that go rancid. White flour keeps longer than whole wheat flour. Freeze flour for 48 hours when you buy it to kill any pantry moth eggs.
Can I use all-purpose flour for bread?
Yes, for most breads. Bread flour has more protein and gives a chewier crumb, but all-purpose flour makes perfectly good bread, especially enriched loaves, flatbreads and quick breads. For a very chewy artisan loaf, bread flour is better — but the difference is texture, not success or failure.