Three Cups of Flour and One Cup of Water
Weigh that card and the bowl holds 381 g of bread flour and 240 g of water. Written on paper it is three to one. In the bowl it is 63%.
Both numbers are correct and only one of them predicts anything. A flour to water ratio says how much water rides on each gram of flour, which is what decides how the dough handles, how fast it proofs, and whether the crumb sets open or tight. Cup counts cannot say that, because a cup of flour and a cup of water are not the same kind of measurement.
How Do You Calculate a Flour to Water Ratio?
Three steps, and the third one is the only one people get wrong.
- Weigh the flour in grams. A cup of bread flour is 127 g on our conversion chart, all-purpose is 120 g, whole wheat is 128 g. One cup, three different weights.
- Weigh the water in grams. A cup is 240 g and a tablespoon is 15 g. A cup filled to the line and a cup filled by eye differ by 10 to 15 g, which is two percentage points on a small batch.
- Divide water by flour. 375 g of water over 500 g of flour is 0.75. Move the decimal two places and it is 75%.
That last number has three names. As a decimal it is 0.75. As a percentage it is 75% hydration. As a ratio it is 4:3, because 0.75 is three quarters and a fraction with a 4 underneath reads as four parts to three. A baker’s percentage is the same division with flour pinned at 100, so it needs no separate method.
Which Side Is Flour?
A ratio written 4:3 has two readings, and they are not close. Flour first gives 3 ÷ 4, or 75% hydration. Water first gives 4 ÷ 3, or 133%, which is a batter.
Cards almost always put flour first, and every bread formula on this site does. When a forum post breaks the rule, the gram weights give it away. Anything claiming to be bread dough at 133% is either a ratio written backwards or a very wet country loaf, and the gram weights tell you which in five seconds.
The Ratio Ladder
Read the left column as flour : water. The middle column is the number you divide flour by to get water.
| Ratio | Fraction | Hydration | Water per 500 g flour |
|---|---|---|---|
| 5:4 | 0.80 | 80% | 400 g |
| 4:3 | 0.75 | 75% | 375 g |
| 3:2 | 0.667 | 66.7% | 333 g |
| 5:3 | 0.60 | 60% | 300 g |
| 2:1 | 0.50 | 50% | 250 g |
| 1:1 | 1.00 | 100% | 500 g |
The conversion runs both ways. From a percentage, 75% is 75/100, which reduces to 3/4, which reads 4:3. From a ratio, the second number divided by the first is the decimal.
Why a 3-to-1 Card in Cups Is 1.6 to 1 in Grams
Volume parts are not weight parts, and the gap is not small.
| Written in cups | In grams | Real ratio |
|---|---|---|
| 1 cup flour : 1 cup water | 120 : 240 | 1:2 (200%) |
| 3 cups bread flour : 1 cup water | 381 : 240 | 1.6:1 (63%) |
| 2 cups flour : 1 cup milk | 240 : 240 | 1:1 (100%) |
A recipe that looks like equal parts is double water by weight. A recipe that reads three to one is closer to one and a half to one. Only a ratio written in grams survives the trip from the page to the bowl.
A cup-written bread recipe can still be good, since the author tuned it by feel over several bakes. Copy the cup counts and you inherit their flour, their scoop, and their humidity.
Reading a Card That Was Written in Cups
Take a plain white bread card: 3 cups bread flour, 1 cup plus 2 tablespoons water, 1½ teaspoons fine salt, 2¼ teaspoons instant yeast.
- Flour: 3 × 127 = 381 g
- Water: 240 + 30 = 270 g
- Ratio: 270 ÷ 381 = 0.709, so 71%
Now the small ingredients, using the chart’s 292 g per cup for fine salt. A teaspoon is about 6 g, so 1½ teaspoons is 9 g, which is 2.4% of the flour. Instant yeast at roughly 3 g per teaspoon gives 7 g, or 1.8%.
The card is a 71% dough at 2.4% salt and 1.8% yeast. That yeast number is high because the formula is built for one afternoon; a cold-fermented version of the same bread would run 0.5% or less. Paste the flour and water weights into the Dough Hydration Calculator and it returns the same 71%, a cheap check on your arithmetic before you commit.
Solving Backward From a Dough Weight
The ratio also works in reverse, which is how you size a batch. Say you want 900 g of dough at 4:3, with 2% salt and 1% instant yeast.
Add the percentages to get the divisor: 100 + 75 + 2 + 1 = 178, so 1.78. Then 900 ÷ 1.78 = 505.6 g of flour. Everything else falls out of the ratio and the two percentages.
| Ingredient | Calculation | Weight |
|---|---|---|
| Bread flour | 900 ÷ 1.78 | 506 g |
| Water | 506 × 0.75 | 380 g |
| Fine salt | 506 × 0.02 | 10 g |
| Instant yeast | 506 × 0.01 | 5 g |
| Total | 901 g |
The extra gram is rounding, not a mistake. Hold the flour at 500 g instead and the dough grows with the ratio: 890 g at 4:3, 915 g at 5:4. Same bag of flour, two different loaves.
Once you have a formula you like, the Recipe Servings Calculator does this multiplication for any target weight without the pencil work.
Four Places the Ratio Stops Describing the Dough
The division is exact. The dough is not.
- Enrichment. Milk is about 88% water, butter about 16%, a large egg about 37 g. A dough built on 500 g flour, 300 g water, 60 g milk, 56 g butter, and one egg reads 60% from the water column and actually carries 399 g of water, which is 80%. Count the water inside the milk, the butter, and the egg or the ratio is fiction.
- Pre-ferment. A 200 g poolish at 100% is 100 g flour and 100 g water. Mix 400 g flour with 275 g water and add that poolish: the bowl arithmetic says 68.8%, and the dough is 75%. The ratio describes the dough, not the mixing bowl.
- Whole grain and rye. Bran and rye pentosans take up more water than white flour does. A 4:3 whole wheat dough feels stiff for the first 20 minutes and slack by the end of bulk. Add 5 points for whole wheat and 8 for rye if you want the same bench feel as white at 4:3.
- Flour moisture. Freshly milled flour holds more water than a bag open since spring, which is why the same formula sometimes needs 10 g more in February than in October.
What the Ratio Leaves Out
Flour and water are two lines of a formula, not the whole thing. Salt sits between 1.8% and 2.2% in most bread, and yeast swings from 0.3% on an overnight cold ferment to 2% for a same-day dough. Neither number belongs in the ratio, and neither can be read off it. Temperature belongs nowhere on the page either, and it moves the schedule more than a point of hydration does. A 4:3 dough mixed at 78°F will be ready in three hours; the same dough at 68°F takes five. The Yeast Calculator handles the percentage side of that, and the Sourdough Calculator does the same job when the leaven is a starter instead of a packet.
Try Our Free Tools
The Dough Hydration Calculator turns your flour and water weights into a percentage and names the band it falls in. The Yeast Calculator converts between instant, active dry, and fresh once you have picked a fermentation time. The Recipe Servings Calculator scales the finished formula by weight or by serving count.
Weigh the flour, weigh the water, divide, and read the answer as a ratio if that is how your head works. 4:3 is 75% and a 3-to-1 card in cups is 63%, and both are correct answers to different questions. The exception is any dough with milk, egg, butter, or a pre-ferment in it, because those carry water the division never sees, and the gap runs from five points to twenty.