How Much to Feed a 1/2 Cup Sourdough Starter? | By Weight

Feed a 1/2 cup starter roughly 113g (1 cup) of flour and 113g (1/2 cup) of water for a standard 1:1:1 ratio by weight.

You pull your sourdough starter from the fridge, pop off the lid, and stare at the jar. The line of bubbly paste sits right at the 1/2 cup mark. Now comes the question that trips up new bakers and experienced ones alike: how much do you feed it? The recipe says “1:1:1” or “equal parts,” but that doesn’t help much when your measuring cup is staring back at you.

The honest answer is that the 1:1:1 ratio is about equal weights, not equal volumes. Since a half-cup of starter weighs roughly 113 grams, a proper feed calls for 113 grams of flour and 113 grams of water. Baking by weight eliminates the guesswork, but plenty of bakers still rely on cups — and there’s a reliable method for that too. Here’s what works.

The 1:1:1 Ratio Makes Sense by Weight

The sourdough world runs on the 1:1:1 ratio. That means equal parts starter, flour, and water. The catch is that these parts are measured by weight, not volume. King Arthur Baking Company, a widely trusted source in the baking community, defines this approach because weight is consistent every time.

Why Weight Beats Volume

Fluffing and settling make cup measurements unreliable. One baker’s scoop of flour might weigh 120 grams while another’s weighs 150 grams. Water is denser than flour, so a volume-based 1:1:1 would actually be out of balance. Using a kitchen scale solves this completely.

The Exact Math for a 1/2 Cup Starter

For a 1/2 cup starter, the math is straightforward. Starter weighs roughly 113 grams. To maintain a 1:1:1 ratio, you mix in 113 grams of flour and 113 grams of water. This gives your yeast and bacteria the precise amount of food they need for a predictable rise.

Why the Volume Confusion Sticks Around

Most home bakers start with cups before they buy a scale. Recipes that rely on volume measurements create a set of conflicting guidelines that make feeding feel more complicated than it should be. Here are the most common volume approaches you’ll find online.

• The 1 cup flour approach: King Arthur Baking’s rough guideline suggests feeding a 1/2 cup starter with 1 cup of flour and 1/2 cup of water. This creates a thick, paste-like batter that many bakers find reliable.
• The equal cups approach: Some sources recommend matching the starter volume with an equal volume of flour and water. This gives you roughly 1/2 cup each, though the water may seem scarce compared to the flour.
• The equal weight converted to cups: Since 113 grams of all-purpose flour is roughly 1 cup (using the spoon-and-level method), feeding 1 cup of flour and slightly less than 1/2 cup of water (about 7 tablespoons) mirrors the 1:1:1 weight ratio.
• The sticky paste method: A handful of baking blogs suggest mixing 1/2 cup of flour with just 1/4 cup of water to create a very stiff starter. This lower hydration can slow down fermentation, which some bakers prefer for longer feeding schedules.

Notice that none of these volume methods are exactly alike. That variability is the reason experienced bakers almost always recommend switching to a scale. Without one, your feeding consistency depends heavily on how you scoop and settle your ingredients.

Adjusting the Ratio for Your Schedule and Needs

The 1:1:1 ratio is a starting point, not a rule carved in stone. Many bakers adjust their feeding ratio to match their schedule. A higher ratio, like 1:4:4 or 1:8:8, stretches the time between feedings because the starter has more food relative to its population, which is why the standard feeding ratio remains a baseline for daily maintenance.

A 1:4:4 feeding (1 part starter, 4 parts water, 4 parts flour) is a common maintenance routine. For a 1/2 cup (113g) starter, that means feeding 452g of flour and 452g of water. This produces a larger volume of active starter, which is useful for baking day.

A 1:8:8 ratio extends the time between feedings even further, up to 10 hours or more. This is useful when you need to leave the starter out while you run errands or sleep in.

How to Feed Your Starter with Minimal Waste

A standard feeding routine often produces more starter than you need, leading to piles of discard that can feel wasteful. Reducing your base starter amount before feeding is a simple way to keep your jar manageable.

1. Downsize your base before feeding. Instead of feeding the full 1/2 cup, keep just 1 tablespoon (roughly 15g) of starter in the jar. Feed it with 15g of flour and 15g of water. This tiny batch is easy to maintain and can be scaled up for baking day.
2. Calculate baker’s percentage for smaller batches. The formula is simple: starter weight x feeding ratio = flour and water needed. If you want a 1:1:1 feed for a 20g starter, you need 20g of flour and 20g of water.
3. Feed from the fridge without discard. If your starter is dormant in the fridge, some bakers pour off the liquid on top (hooch) and feed directly without discarding the base amount. This works best if the starter volume is small.
4. Use discard in other recipes. Discard is great for pancakes, waffles, crackers, or quick breads. Keeping a jar of discard in the fridge lets you build up a useful supply for these recipes.

Maintaining a smaller starter means you only build it up when you’re ready to bake. This approach saves flour and keeps your kitchen routine flexible. Many bakers find it reduces the pressure of a daily feeding schedule.

Feeding a 1/2 Cup Starter Using Volume Measurements

If you don’t own a kitchen scale, you can still feed your starter with fair accuracy using measuring cups. The trick is understanding that flour volume varies. The most common guideline from major baking brands is to feed a 1/2 cup starter with 1 cup of flour and 1/2 cup of water.

Some smaller baking sources suggest adjusting this ratio slightly. For a 1/4 cup of starter, mixing 1/2 cup of flour and 1/4 cup of water creates a stiff paste that works well, according to the feeding smaller starter guide. Scaling that up to a 1/2 cup starter would mean roughly 1 cup of flour and 1/2 cup of water.

The consistency of your starter is a more reliable indicator than the exact volume. After feeding, the mixture should look like thick pancake batter — spoonable but not runny. If it’s too stiff, add a tablespoon of water. If it’s too runny, add a tablespoon of flour.

The Bottom Line

Feeding a 1/2 cup sourdough starter comes down to the 1:1:1 ratio by weight — roughly 113 grams each of flour and water. Volume methods work in a pinch, but they introduce variability that can affect your starter’s activity and ripening time. Using a kitchen scale is the single most reliable way to achieve consistent results.

Your feeding ratio should match your baking schedule and the recipe you plan to use — a stiff starter works differently in a rustic loaf than a high-hydration one. If you’re new to sourdough, starting with the standard 1:1:1 by weight gives you a reliable benchmark to adjust from.