A quart-size Weck jar (about 32 ounces) is the best starting point for most home sourdough bakers
A quart-size Weck jar — the straight-sided glass jars with the distinctive wire bail and rubber gasket — holds enough starter to feed a loaf or two without taking up excessive counter space. The 32-ounce capacity gives you room to feed your starter, watch it rise and fall, and still have headroom so it doesn't overflow when it peaks. Weck jars come in several sizes, and the quart is the sweet spot for a baker who bakes once or twice a week.
If you bake more often or keep multiple starters, a half-gallon Weck (64 ounces) prevents you from feeding constantly. If you bake less frequently or want a smaller footprint, a pint-size Weck (16 ounces) works, though you'll need to feed more often relative to the volume. The jar size doesn't change how your starter ferments — it changes how often you feed it and how much counter space it claims.
Key Takeaways
- A quart-size Weck jar (32 ounces) is the standard choice because it holds enough starter for regular baking without excessive feeding.
- Half-gallon Weck jars (64 ounces) suit bakers who bake multiple times a week or keep more than one starter.
- Pint-size Weck jars (16 ounces) work for occasional bakers but require more frequent feeding relative to the volume you keep.
- The straight sides of Weck jars make it straightforward to see your starter rise and fall, which helps you learn its rhythm.
- Weck jars are not airtight, so your starter can breathe; you can cover them loosely with a cloth or use the lid without the gasket.
Why Weck jars work better than mason jars for sourdough
Weck jars have straight sides instead of the tapered shoulders of a mason jar. This matters because you can see your starter rise and fall clearly — the straight walls show you exactly how much your starter has grown, which helps you learn when it's ready to use. A mason jar's shoulders hide the action near the top, making it harder to judge the peak.
Weck jars also don't seal airtight the way a mason jar does when you tighten the lid. Your sourdough starter is a living culture that produces gas; it needs to breathe. With a Weck jar, you can leave the lid on loosely, or use the lid without the rubber gasket and wire bail, and your starter stays protected from dust and debris without pressure building up inside. A sealed mason jar can crack or pop the lid if gas builds up too much.
How to measure your feeding schedule against jar size
The size you choose depends on how often you bake and how much starter you use per loaf. Most sourdough recipes call for 50 to 100 grams of active starter — the starter at its peak, when it's risen and bubbly. A quart-size Weck jar holds roughly 240 grams of starter when full, so you can feed it once a day and still have enough to bake with.
If you bake twice a week, a quart jar means feeding your starter once daily at room temperature, or keeping it in the refrigerator between bakes and feeding it less often. If you bake four or five times a week, a half-gallon jar lets you maintain more starter without feeding so frequently. If you bake once every two weeks, a pint jar keeps a smaller culture alive, though you'll feed it more often relative to how much you're keeping.
The math is straightforward: a larger jar means you feed less often. A smaller jar means you feed more often but waste less starter if you're not baking regularly. Neither is wrong — it's about matching the jar to your baking rhythm.
What happens if your jar is too small
A jar that's too small forces you to feed your starter more often than necessary, or to discard more of it before each feeding. If you keep a pint of starter and bake only once a week, you're either feeding it daily (which uses flour and time) or discarding half of it at each feeding (which wastes starter and money). Over time, this becomes tedious.
A jar that's too small also overflows more easily. Sourdough starter can double or triple in volume when it's fed and active. If your jar is only half full to begin with, the starter has nowhere to go and ends up on your counter. A quart jar gives you enough headroom that this rarely happens with normal feeding ratios.
What happens if your jar is too large
A jar that's too large doesn't cause problems — it just means you're keeping more starter than you need. A half-gallon jar is fine if you bake frequently, but if you bake once a week, you're maintaining 64 ounces of starter when 32 ounces would do the job. That's extra flour and water you're feeding every day, and extra starter you're discarding at each feeding.
The only real downside is waste and the space it takes up. A larger jar doesn't hurt your starter or change how it ferments. If you have the counter space and don't mind the extra feeding, a larger jar is perfectly fine.
Weck jar sizes and what they hold
| Weck Jar Size | Volume | Best For |
|---|---|---|
| Pint | 16 ounces | Occasional bakers or those experimenting with sourdough |
| Quart | 32 ounces | Regular home bakers who bake one or two loaves per week |
| Half-gallon | 64 ounces | Frequent bakers or those keeping multiple starters |
How to set up your Weck jar for daily feeding
Once you've chosen your size, fill the jar about one-third full with your starter. This gives you room for the starter to rise without overflowing, and it leaves space for you to add fresh flour and water at each feeding. A typical feeding ratio for a quart jar is 1 part starter, 1 part flour, 1 part water by weight — for example, 50 grams starter, 50 grams flour, 50 grams water.
Cover the jar loosely with a cloth, a coffee filter held on with a rubber band, or the Weck lid without the gasket and bail. The goal is to keep dust and debris out while letting gas escape. Leave it on your counter at room temperature, or in a cool spot if your kitchen is very warm. Feed it once daily at roughly the same time each day, and within a few days you'll see a pattern emerge — your starter will rise and fall on a predictable schedule.
Frequently Asked Questions
Can I use a regular mason jar instead of a Weck jar?
Yes, a mason jar works for sourdough starter. The main drawbacks are that the tapered shoulders make it harder to see how much your starter has risen, and you need to be careful not to seal it airtight. Leave the lid off or use it very loosely so gas can escape. Weck jars are more convenient because their straight sides show the rise clearly and they're designed to stay loosely covered.
What if I want to keep my starter in the refrigerator instead of on the counter?
The jar size matters less if you refrigerate your starter, because cold slows fermentation dramatically. You can feed it once a week instead of daily, so a smaller jar is fine. A pint or quart Weck jar works equally well in the fridge. When you're ready to bake, take it out, feed it, and let it come to room temperature and peak before you use it.
Do I need to use the Weck lid and gasket, or can I just cover it with cloth?
A cloth cover works fine and is what many bakers use. The Weck lid without the gasket and bail also works — it sits on top loosely and keeps dust out while letting gas escape. The gasket and bail are designed for canning, where you need an airtight seal. For sourdough starter, you don't need that seal, so use whichever cover is most convenient for you.
Should I buy a Weck jar with straight sides or one with a wider mouth?
Weck makes several shapes. The straight-sided quart jars are the most popular for sourdough because the straight sides let you see the rise clearly. Wider-mouth jars are easier to scoop starter out of, but they're less common. A standard quart Weck jar works well for both visibility and scooping.
Can I use the same Weck jar for both storing and baking with my starter?
Yes. Many bakers keep their starter in a Weck jar on the counter, feed it there, and scoop out what they need directly into their mixing bowl. You don't need a separate jar for storage and another for baking. One quart Weck jar is your starter's home.