Sourdough Starter (100% hydration): Grams to Cups
1 cup of sourdough starter (100% hydration) = 227 grams
One US cup of sourdough starter (100% hydration) weighs 227 grams. One 250 ml metric cup — the one used in the UK, Australia, New Zealand and Canada — holds 240 grams. To convert any weight, divide the grams by the figure for your cup.
A cup of fed, 100% hydration sourdough starter weighs about 227 g — King Arthur Baking gives 227–241 g, depending on how active it is. Stir it down before measuring: a bubbly starter traps gas and a cup of it weighs less.
Why starter is best weighed
Sourdough starter is flour and water fermented together, and most recipes assume a 100% hydration starter — equal weights of flour and water. It is also full of gas. A starter at its peak can be half bubbles by volume, so a cup of it weighs noticeably less than a cup of the same starter stirred down. King Arthur Baking's chart gives a range for exactly that reason: 227 to 241 g per cup. This site uses 227 g, the lower end, which matches a stirred, fed starter.
Recipes written in grams (most sourdough recipes are) do not have this problem, which is why converting a gram amount to cups should be a last resort. If you do, stir the starter down with a spoon, pour it into a measuring cup and level it.
Common amounts
At 227 g per cup: 50 g of starter is about 0.22 cups (3½ tablespoons), 100 g is about 0.44 cups (a scant ½ cup), 150 g is about 0.66 cups (⅔ cup), 200 g is about 0.88 cups and 250 g is about 1.1 cups.
A stiff starter kept at lower hydration, or one fed with whole-wheat or rye flour, will not match these figures; they are for a flour-and-water starter at equal weights.
Starter and discard
Discard is the same starter, usually less active, so it usually holds less gas and sits nearer the top of the King Arthur range, up to about 241 g per cup. Discard recipes (crackers, pancakes) are forgiving, so the difference rarely matters.
Where the 227 g figure comes from
- King Arthur Baking ingredient weight chart: Sourdough starter, 1 cup = 227 g (chart)
This site uses 227 g per US cup of sourdough starter (100% hydration), spooned and levelled. References checked September 2026.
How many cups is X grams of sourdough starter (100% hydration)?
| Grams | US cups | Metric cups | Tablespoons | Ounces |
|---|---|---|---|---|
| 25 g sourdough starter (100% hydration) | ⅛ | ⅛ | 1.76 | 0.88 |
| 50 g sourdough starter (100% hydration) | ¼ | ¼ | 3.52 | 1.76 |
| 75 g sourdough starter (100% hydration) | ⅓ | ⅓ | 5.29 | 2.65 |
| 100 g sourdough starter (100% hydration) | ½ | ⅜ | 7.05 | 3.53 |
| 110 g sourdough starter (100% hydration) | ½ | ½ | 7.75 | 3.88 |
| 120 g sourdough starter (100% hydration) | ½ | ½ | 8.46 | 4.23 |
| 125 g sourdough starter (100% hydration) | ½ | ½ | 8.81 | 4.41 |
| 130 g sourdough starter (100% hydration) | ⅝ | ½ | 9.16 | 4.59 |
| 140 g sourdough starter (100% hydration) | ⅝ | ⅝ | 9.87 | 4.94 |
| 150 g sourdough starter (100% hydration) | ⅔ | ⅝ | 10.57 | 5.29 |
| 170 g sourdough starter (100% hydration) | ¾ | ¾ | 11.98 | 6.00 |
| 175 g sourdough starter (100% hydration) | ¾ | ¾ | 12.33 | 6.17 |
| 200 g sourdough starter (100% hydration) | ⅞ | ⅞ | 14.1 | 7.05 |
| 225 g sourdough starter (100% hydration) | 1 | 0.94 | 15.86 | 7.94 |
| 240 g sourdough starter (100% hydration) | 1.06 | 1 | 16.92 | 8.47 |
| 250 g sourdough starter (100% hydration) | 1⅛ | 1.04 | 17.62 | 8.82 |
| 275 g sourdough starter (100% hydration) | 1¼ | 1⅛ | 19.38 | 9.70 |
| 300 g sourdough starter (100% hydration) | 1⅓ | 1¼ | 21.15 | 10.58 |
| 350 g sourdough starter (100% hydration) | 1½ | 1½ | 24.67 | 12.35 |
| 400 g sourdough starter (100% hydration) | 1¾ | 1⅔ | 28.19 | 14.11 |
| 450 g sourdough starter (100% hydration) | 2 | 1⅞ | 31.72 | 15.87 |
| 500 g sourdough starter (100% hydration) | 2¼ | 2⅛ | 35.24 | 17.64 |
Cups to grams: how many grams in ½ cup, ¼ cup or 1 cup of sourdough starter (100% hydration)?
| Cups | Grams (US cup) | Grams (250 ml metric cup) |
|---|---|---|
| ⅛ cup sourdough starter (100% hydration) | 28 g | 30 g |
| ¼ cup sourdough starter (100% hydration) | 57 g | 60 g |
| ⅓ cup sourdough starter (100% hydration) | 76 g | 80 g |
| ½ cup sourdough starter (100% hydration) | 114 g | 120 g |
| ⅔ cup sourdough starter (100% hydration) | 151 g | 160 g |
| ¾ cup sourdough starter (100% hydration) | 170 g | 180 g |
| 1 cup sourdough starter (100% hydration) | 227 g | 240 g |
| 1¼ cups sourdough starter (100% hydration) | 284 g | 300 g |
| 1⅓ cups sourdough starter (100% hydration) | 303 g | 320 g |
| 1½ cups sourdough starter (100% hydration) | 341 g | 360 g |
| 2 cups sourdough starter (100% hydration) | 454 g | 480 g |
| 3 cups sourdough starter (100% hydration) | 681 g | 720 g |
How to measure sourdough starter (100% hydration) accurately
The 227 g figure assumes the spooned-and-levelled method: spoon the sourdough starter (100% hydration) into a dry measuring cup and sweep the top flat with a straight edge. Scooping the cup through the bag compacts it and gives a heavier cup.
- 1 US cup of sourdough starter (100% hydration) = 227 g
- 1 metric cup (250 ml) of sourdough starter (100% hydration) = 240 g
- ¾ cup = 170 g
- ½ cup = 114 g
- ⅓ cup = 76 g
- ¼ cup = 57 g
- 1 tablespoon = 14.2 g
Frequently asked questions
How many cups is 100 grams of sourdough starter (100% hydration)?
100 grams of sourdough starter (100% hydration) is about ½ US cups, based on 227 g per cup, or ⅜ metric cups.
How many grams in a cup of sourdough starter (100% hydration)?
One US cup of sourdough starter (100% hydration) weighs 227 grams. A 250 ml metric cup holds 240 grams.
How many grams is ½ cup of sourdough starter (100% hydration)?
½ US cup of sourdough starter (100% hydration) weighs about 114 g; ¼ cup about 57 g and ¾ cup about 170 g.
How many cups is 250 grams of sourdough starter (100% hydration)?
250 grams of sourdough starter (100% hydration) is about 1⅛ US cups, or 1.04 metric cups.
Does a UK cup of sourdough starter (100% hydration) weigh the same as a US cup?
No. A UK, Australian or Canadian metric cup is 250 ml against the US 236.6 ml, so it holds about 5.7% more — 240 g of sourdough starter (100% hydration) rather than 227 g.
How many tablespoons is 100 grams of sourdough starter (100% hydration)?
100 grams of sourdough starter (100% hydration) is about 7.05 tablespoons.
How many cups is 100 g of sourdough starter?
About 0.44 cups — a scant ½ cup — for a fed, stirred-down 100% hydration starter at 227 g per cup.
How many cups is 150 g of sourdough starter?
About ⅔ cup (0.66 cups).
How much does a cup of sourdough starter weigh?
227–241 g according to King Arthur Baking; a bubbly starter sits at the low end and a stirred-down or discard starter at the high end.