500 Grams of Flour at 70% Takes 350 Grams of Water
Bowl on the scale, tare, 500 g of bread flour. The water line is one multiplication away: 500 × 0.70 = 350 g. Weigh 350 g of water into that bowl and the dough is at 70% hydration.
That is the whole answer, and it is worth knowing why it feels too short. Most recipes hide the number inside a list of cups, and most bakers end up adding water by feel because nobody told them the flour weight is the only figure that matters. Two numbers and a decimal, and the guesswork is gone.
If you would rather type than multiply, the Dough Hydration Calculator takes the flour weight and a target percentage and returns the water in grams, ounces, or milliliters.
The Formula, Written Out Once
Water weight = flour weight × hydration percentage ÷ 100
Run it forward and 500 g at 70% is 350 g. Run it backward and 500 g of water at 70% needs 714 g of flour. Everything else in this article is that equation applied to a different starting point.
Here is what the 500 g batch looks like as a complete formula with salt and yeast in it:
| Ingredient | Weight | Baker’s percentage |
|---|---|---|
| Bread flour | 500 g | 100% |
| Water | 350 g | 70% |
| Fine sea salt | 10 g | 2% |
| Active dry yeast | 6 g | 1.2% |
| Total | 866 g | 173.2% |
The 866 g at the bottom is the dough weight, and it is the number that decides whether this batch fits your pan. A 9x5 inch loaf pan wants 800 to 850 g of dough, so 500 g of flour overshoots by about 20 g. Drop to 491 g of flour, 344 g of water, and 9.8 g of salt and the same dough fills the pan to the right height. The percentage does not move. Only the flour line does.
What the 500 Grams Has to Mean
The 350 g answer is only correct if 500 g is the total flour in the dough, and it usually is not what the bowl contains.
Anything that already carries flour counts toward the 500. That includes a poolish, a biga, a levain, and the whole wheat portion of a blend. Skip this and the water number stays right while the hydration quietly climbs.
A worked case. You want 500 g of total flour at 70%, and the recipe calls for a 100 g poolish at 100% hydration:
- The poolish is 50 g flour and 50 g water.
- Flour to scoop: 500 − 50 = 450 g.
- Water to pour: 350 − 50 = 300 g.
Check it before mixing: 300 + 50 = 350 g of water, 450 + 50 = 500 g of flour, and 350 ÷ 500 = 70.0%. Same target, two very different sets of numbers on the counter. The Sourdough Calculator does this subtraction for you when the pre-ferment is a starter rather than a poolish, since a starter’s flour and water have to come out of the totals the same way.
350 Grams of Water in a Measuring Cup
Water is the one ingredient where grams and milliliters are interchangeable: 350 g is 350 mL, near enough for any kitchen.
Our conversion chart uses 240 g per cup for water, so 350 g is 1.46 cups, or 1 cup plus 7 tablespoons. By volume in fluid ounces that is about 11.8 fl oz. Close is fine here, because a 5 g error in water moves a 500 g batch by one percentage point.
| Flour | Water at 70% | Water by volume (240 g/cup) | Finished dough |
|---|---|---|---|
| 250 g | 175 g | ¾ cup minus 1 teaspoon | 433 g |
| 500 g | 350 g | 1 cup + 7 tbsp | 866 g |
| 750 g | 525 g | 2 cups + 3 tbsp | 1,299 g |
| 1,000 g | 700 g | 2⅞ cups | 1,732 g |
Doubling is the only operation in that table. Two 500 g batches are 1,000 g of flour and 700 g of water, and nothing in the method changes.
Going the Other Way: From a Dough Weight to 350 Grams
Sometimes the flour weight is the unknown. You have a pan, or a target loaf size, and the water follows from the dough weight.
Flour = dough weight ÷ 1.732, where 1.732 is the sum of flour at 100%, water at 70%, salt at 2%, and yeast at 1.2%.
| Target dough | Flour | Water at 70% | Salt | What it fills |
|---|---|---|---|---|
| 650 g | 375 g | 263 g | 7.5 g | 8.5x4.5 inch pan |
| 850 g | 491 g | 344 g | 9.8 g | 9x5 inch pan |
| 1,700 g | 982 g | 687 g | 19.6 g | Two 9x5 pans |
| 2,000 g | 1,155 g | 809 g | 23.1 g | A large round or a sheet |
Those 1,700 g figures are the ones worth taping inside a cabinet door. Two sandwich loaves, one mixing bowl, no arithmetic at 6 a.m.
The Mistake That Turns 70% Into 233%
The percentage is measured against flour. Not against the dough, not against the water, not against the total on the scale.
Someone aiming for an 850 g loaf who takes 70% of 850 lands on 595 g of water, leaves 255 g for the flour, and mixes a batter at 233% hydration. It will not shape. It will not even come together. The flour is the 100%, always, and the water is a fraction of it.
The second version of the same error is measuring both by volume. One cup of all-purpose flour weighs about 120 g and one cup of water weighs 240 g, so equal cups of each is a 200% dough, not a 100% one. Flour and water only match at 1:1 when both are on a scale.
Where the 350 Gram Answer Drifts
The arithmetic is exact. The flour is not.
Scooped flour. Four cups of bread flour at 127 g per cup is 508 g, so 350 g of water reads 68.9%. Pack the scoop to 132 g per cup and four cups is 528 g, which drops the same water to 66.3%. Weigh the flour once and this entire class of error disappears.
A whole wheat blend. Whole wheat absorbs 5 to 10 points more water than white flour before it feels the same. A 70% dough with 30% whole wheat handles like a 62% white dough, even though the math is identical.
Flour that has been open for months. Wheat flour picks up and loses moisture with the room. The difference is small, maybe 1 to 2 points, and it shows up as a dough that needs a splash at the end of mixing.
Recipes that quote hydration to a decimal. 70.0% on a home scale with 1 g resolution is honest to about half a point. Treat anything past that as decoration.
Hold Back 25 Grams and Add It Later
Take 25 g out of the 350 and set it aside. Mix with 325 g, which is 65%, and the dough comes together faster and handles easier. Add the held-back water during the second fold, 10 g at a time, letting each addition absorb before the next.
The final hydration is still 70%. Only the order changed, and the order matters more than most formulas admit. A 65% mix followed by a hydration bump gives a stronger gluten network than dumping all 350 g in at once, because the flour hydrates in two stages instead of drowning.
Water temperature is the other lever at this stage. For a 76°F dough with 68°F flour in a 71°F kitchen, the water should be 89°F: (3 × 76) − 68 − 71. Cold water out of the tap will push bulk fermentation from 3 hours to 5.
Try Our Free Tools
The Dough Hydration Calculator gives you the water weight for any flour weight and percentage, in either direction. The Yeast Calculator sizes the 6 g of active dry yeast for your dough type and rise schedule, and converts it to instant or fresh. The Recipe Servings Calculator rescales a whole written card when you want two loaves instead of one. Free, instant, no signup.
For 500 g of flour at 70% hydration, weigh 350 g of water. The exception is flour that went into the bowl by the cup, because then the 500 g is an estimate and the 70% describes your scooping more than it describes the bread.