Chris Collins

Tools · cooking

Sourdough starter and levain planner

Feed a sourdough starter at any ratio, build exactly the levain a recipe needs (counting the starter's own water), estimate when it will peak at your kitchen's temperature — calibrated to your starter — and plan bake day backwards from when the loaf goes in the oven, with a printable timeline, calendar file and reminders.

Added

Works with

How to use it

How to use it

Set Starter sits at to the temperature where the jar lives; every estimate uses it.

Feed — a ratio of starter : flour : water (1:1:1, 1:5:5, …) from the starter you keep or the total you want, with the feed’s hydration and roughly when it will peak.

Build a levain — how much the recipe needs, at what hydration, plus a little to keep. Give your starter’s hydration and how much fresh flour per gram of starter (2 is about 1:2:2; 5 is slower and milder). The water is chosen so the whole levain lands on its hydration, counting the flour and water already in the starter — so a stiff levain from a liquid starter comes out right. Set when you will mix the dough to see when to feed it. The bread tool links here with the levain its formula needs.

Peak time — a chart of hours to peak against temperature for common ratios. Calibrate it to your own starter: enter the ratio, how long it took to peak and how warm it was, then Use my starter’s timing; every other estimate follows.

Bake-day schedule — when the loaf goes in the oven, the dough’s temperature in bulk and the levain share, and whether the shaped loaves proof overnight in the fridge. Levain and bulk times left empty are estimated; type your own to override them. The timeline lists every step with day and time. Print prints just the timeline; Add to calendar downloads an .ics file with an alert at each step — the reliable way to be reminded on a locked phone. Remind me sounds an alarm and shows a notification at each step while the page stays open (with Keep screen on where the browser supports it).

Limits

  • All the times are rules of thumb. Peak: time ≈ a lag plus a doubling time × log2(how much the feed diluted the starter), the doubling time halving for every 10 °C warmer; the default — 1:1:1 peaking in about 4½ h at 24 °C — is typical, not universal. Bulk: about 4½ h at 24 °C with 20 % levain, doubling for every 10 °C cooler. Flour, the starter’s health and the dough decide: bulk is done when the dough has risen 50–75 %, domed and bubbly.

  • Reminders need the page open; phones pause background pages. Use the calendar file.

  • Grams are shown in ounces with US units, but scales in grams are far easier for this.

Linking to an example

Add the tab after #: feed, build, peak or schedule. Temperatures are in °C, weights in grams.

Parameter Meaning Example

t

Where the starter sits, °C

t=21

r, fmode, have, want

Feed: ratio, have (starter kept) or want (total), and the grams

r=1:5:5&fmode=have&have=20

need, lh, sh, x, keep, mixat

Build: levain needed, its hydration %, your starter’s hydration %, fresh flour per gram of starter, extra to keep, mixing time

need=200&lh=100&x=2&mixat=09:00

cal, cr, chrs, ct

Peak: calibration factor; or the ratio, hours to peak and °C you observed

cal=1.3

bake

Schedule: when the loaf goes in, YYYY-MM-DDTHH:MM local time

bake=2026-10-18T09:00

bt, lp, retard, proof, bulk, lev

Bulk temperature °C, levain % of flour, fridge proof (1/0), proof hours, bulk hours, levain hours

bt=24&retard=1&proof=14

mix, shape, heat, bk, cool

Minutes to mix, shape, preheat, bake and cool

heat=45&bk=40

example

One of the presets below

example=country-levain

example= Shows

daily-feed

Keep 20 g and feed 1:1:1 (open)

overnight-feed

A 1:5:5 feed at 21 °C, about 10–11 h to peak (open)

country-levain

200 g of 100 % levain plus 20 g to keep, seeded 1:2:2 (open)

stiff-levain

A 50 % levain from a 100 % starter (open)

weekend-bake

A bake with an overnight 14 h cold proof (open)

Runs entirely in your browser; nothing you type leaves this page.