Sourdough Starter Feeding Planner
Turn starter feeds into a clear discard plan
Sourdough starter feeding, ratios and discard FAQ
How often should I feed my sourdough starter?
At room temperature, many bakers feed their starter once or twice a day depending on how warm the kitchen is and how much they bake. In the fridge, a healthy starter often needs a full feed about once a week, then a couple of room-temperature feeds to wake it up before baking. Use this calculator to plan each full feed and keep the ratios consistent over time.
What does a 1:2:2 feed ratio actually mean?
A ratio like 1:2:2 is read as parts of starter : flour : water by weight. If you keep 20 g of old starter, you add 40 g flour and 40 g water. The tool uses your target “starter needed” amount to scale those parts up or down and then shows exactly how much to discard before feeding so you land on that target.
Which starter hydration should I choose?
If you are not sure, choose Everyday 100% hydration, which means equal weights of flour and water. A stiff starter (around 80%) has more flour and holds its shape like dough; a liquid starter (around 125%) is looser and tends to ferment faster. The hydration choice in this tool mostly affects the final hydration estimate in the result box.
Why does the tool ask for “starter currently in jar”?
To work out discard, the calculator needs to know how much starter you have now. It compares that with the amount of old starter the ratio requires. If you have more, the extra becomes discard. If you have less than needed, the summary will flag that you need to build up your starter over a couple of feeds before using the plan.
Is sourdough discard safe to use in pancakes and waffles?
In a healthy starter that smells pleasantly sour or yeasty, discard is simply a mix of fermented flour and water. Most bakers keep it in the fridge for a few days and use it in cooked recipes like pancakes, waffles, crackers or quick breads. If discard ever smells rotten, looks streaky or grows coloured mold, throw it away and wash the container well before starting again.
Can this calculator tell me exactly when my starter is ready?
Not exactly. The timing estimate is a ballpark window based on ratio, temperature and hydration. Your actual starter will also be affected by flour type, water, jar shape and how active the culture is today. Always cross-check with visual cues: look for doubling in size, plenty of bubbles, and a domed top that is just starting to level off.
How much starter should I keep between bakes?
Many home bakers keep a small mother starter in the fridge, often 25–60 g, and build a separate levain for each bake. This calculator can be used either way: set a small target amount for fridge storage feeds, or a larger target when you are building a levain for a specific recipe.
What’s the safest way to throw away old starter?
Avoid tipping large amounts of starter down the sink; it can set like glue in plumbing. It’s safer to scrape discard into a lined bin, add it to a compost pail if you have one, or cook it into pancakes, crackers or waffles. When in doubt, treat old starter like any other perishable food and dispose of it with household waste rather than washing it into the drains.
How to use this sourdough starter feeding calculator
This tool turns starter feeding into a small, repeatable routine. Instead of guessing how much to discard or feed, you set a target starter amount and a ratio, and the calculator outputs a plan you can tape to your jar or note app.
1. Pick weight units and starter style
For accuracy, leave the calculator on grams unless your scale can only show ounces. Choose a starter style that matches how your culture behaves now: a typical white or mostly-white starter is usually close to 100% hydration. Stiff and liquid options tweak the final hydration estimate and can help you compare different feeding styles.
2. Set how much starter you need and the feed ratio
Under “Starter needed after feeding”, enter the total amount you want ready at peak, including what goes into the dough and what you will keep back. Then pick a feed ratio. Ratios with more fresh flour and water (1:3:3 or 1:5:5) rise more slowly and work well for overnight or cool feeds; lower ratios (1:1:1 or 1:2:2) are better for same-day bakes in a warm kitchen.
3. Weigh the starter you already have
Put your jar on the scale, tare it to zero, then scrape the starter into the jar and note the weight for “Starter currently in jar”. This does not need to be perfect; a close estimate is usually enough for discard planning. Choose where the starter will sit after feeding—warm counter, normal room, cool room or fridge—so the calculator can suggest a rough “ready in” window.
4. Read the feed plan and hydration box
When you tap Plan this feeding, the result card shows:
- How much starter to keep in the jar and how much to discard.
- Flour and water to add in your chosen units (with grams in brackets).
- The starter style and final hydration % after the feed.
- A rough time window when the starter should be at or near its peak in your environment.
If you do not have enough starter for the chosen ratio, the summary will say so and tell you how much you need to build up to over a couple of feeds.
5. Copy the plan into your baking notes
Use the Copy summary button to drop the full feed plan into your recipe notebook, spreadsheet or messaging app. Keeping a few weeks of starter logs makes it easier to spot patterns: which ratios you liked, how long feeds took to peak at different temperatures, and how the starter behaved before your best loaves.
Over time this calculator becomes a simple starter dashboard: it keeps hydration, ratios and discard under control so you can focus on dough feel, proofing and baking.
How the sourdough starter feeding math works
The feeding planner uses straightforward weight-based maths so you can reproduce or tweak the numbers with a pocket calculator any time.
1. Converting everything to grams
Whatever unit you choose, the tool converts amounts to grams internally:
grams = ounces × 28.3495
ounces = grams ÷ 28.3495
Grams are then used to calculate seed starter, discard and feed amounts; at the end, the result is formatted back into grams or ounces depending on your unit choice.
2. Using the feed ratio to find seed, flour and water
For a chosen ratio S:F:W (starter : flour : water) and a target total starter weight T after the feed:
total_parts = S + F + W
multiplier = T ÷ total_parts
seed_starter = S × multiplier
flour_to_add = F × multiplier
water_to_add = W × multiplier
The seed starter is the amount you must keep in the jar before feeding. If your current starter is heavier than this number, the difference is the discard.
3. Estimating hydration from starter style
For the chosen starter style, the calculator stores a hydration percentage H (for example 100% for equal flour and water). If the seed starter weight is S, then:
flour_in_seed = S ÷ (1 + H/100)
water_in_seed = S − flour_in_seed
After adding new flour and water, the estimated final hydration is:
hydration% = (water_in_seed + water_to_add) ÷ (flour_in_seed + flour_to_add) × 100
This stays an approximation—real starters may drift slightly wetter or drier—but it keeps you in the right ballpark.
4. Rough “ready in” timing by ratio and environment
Each feed ratio is mapped to a simple base rise window at normal room temperature:
- 1:1:1 · roughly 4–6 hours.
- 1:2:2 · roughly 6–8 hours.
- 1:3:3 · roughly 8–10 hours.
- 1:5:5 · roughly 10–12 hours.
The environment choice then stretches or shrinks that window. Warm kitchens shorten times, cool rooms lengthen them, and fridge feeds are treated as 24–72 hour maintenance feeds rather than same-day levain builds.
5. Turning timing into a green, amber or red flag
To keep things readable, the tool labels the feeding plan:
- GREEN for typical same-day or overnight feeds (roughly 4–16 hours).
- AMBER for very quick or quite long room-temperature feeds.
- RED for fridge-based or multi-day schedules where you’ll want to plan carefully around your bake.
The flag is a planning hint, not a safety guarantee. Always combine this maths with visual cues, smell and food-safety common sense when deciding whether a starter is ready to bake with.
References and further reading on sourdough starter feeding and safety
Pair this feeding planner with detailed guides from experienced bakers and food-safety resources:
- King Arthur Baking — Feeding and maintaining your sourdough starter — step-by-step instructions for room-temperature and refrigerated starters, with example feed amounts.
- King Arthur Baking — Maintaining your sourdough starter — overview of feeding frequency, storage and signs of a healthy, active starter.
- The Perfect Loaf — How do I feed my sourdough starter? — deep-dive into feeding ratios, temperature and how they change fermentation timing.
- The Perfect Loaf — Keeping a smaller sourdough starter to reduce waste — strategies to keep starter volumes low while maintaining activity and reliability.
Use the calculator for quick numbers, and lean on these guides—and your own notes—for fine-tuning feed schedules, flours and baking plans in your kitchen.