Knowing when you can stop kneading the dough is among the more mysterious aspects of baking bread. Sure, it's no longer a wobbly mess of bubble-gummy dough, but is it really done? Here are a few clues to look for.
The point of kneading dough is to strengthen the gluten, which are the stringy bands of proteins that give bread its structure and texture. As you (or your stand mixer!) work the dough, those strands of gluten are tightening up and getting into line.
Kneading for 10-12 minutes by hand or 8-10 minutes in a mixer are the general standards; if you've been massaging the dough for that length of time, you can be pretty confident that you've done your job. Here are a few other things to look for:
1. Smooth Dough - The dough will start out looking like a shaggy, lumpy mass and will gradually smooth out as you knead. By the time you finish, it should be completely smooth and slightly tacky to the touch.
2. Holds Its Shape - Lift the ball of dough in your hand and hold it in the air for a second. If it holds its ball shape, that means the gluten is tight and strong. If it sags down between your fingers, the gluten is still loosey-goosey and needs some more kneading.
3. The Poke Test - Give that ball of dough a firm poke with your finger. If the indentation fills back quickly, you're good to go. If it stays looking like a deep dimple, continue kneading.
4. The Windowpane Test - Pull off a golf-ball-sized piece of dough and stretch it into a thin sheet between your fingers (as pictured above). If the gluten is well-developed, the dough will stretch into a paper-thin film without breaking. If quickly breaks...you guessed it, keep kneading.
5. When You're Tired - You may laugh, but this is true! If you've been kneading for 10-12 minutes and your arms are tired, the dough is probably good. (If you get tired before that time is up, it's ok to rest for a few minutes and come back to it.) As long as your dough is close to passing the tests mentioned above, even if you're not 100% confident, you can consider yourself within range and call it a day.
For a more detailed look at kneading dough and how to tell when it's done, check out this video:
• How to Knead Bread Dough: The Video
Do you have other tips for knowing when your bread dough is kneaded?
Related: Bake Bread! 20 Tips, Tricks, and Ideas for No-Knead Bread
(Images: Faith Durand)
Elizabeth Apron fro...

A pinch test is what I do - if you pinch it and it springs right back, it's good. Also, if it's becoming stiff and is starting to tear, you have kneaded it too long. I generally use my stand mixer with a hook for the dough and then finish it off the counter in 5 seconds flat.
That is, on the counter.
Doesn't this depend on the kind of dough you are kneading?
A baker can over knead too. I think it's important to let new baker's know what to look for when the dough has been over worked.
Quite timely, as I began my first sourdough starter this weekend. Can't wait to get to this part for my first loaf!
I think I might have the problem of overkneading. I have a stand mixer and I use it, and I feel like the dough is never done at 10 minutes. But I also feel like it's not done after fifteen, or even twenty. It never windowpanes at all. So, maybe I'm not checking it early enough? The bread seems to turn out ok, but is often sort of heavy and dense. Advice?
@gildeddawn - you may need to let your dough rise more after kneading/right before baking. I've always found that when I'm baking bread at home, my apartment is a bit cooler (unless the oven is already on) and it will take up to an hour or two longer to proof than a recipe calls for.
What if you have been kneading for 30+ minutes and it's still not smooth?
Hmm...perhaps a second post on over-kneading is required! It's definitely easy to over-knead in a stand mixer because it's so powerful; less likely when you're kneading by hand.
I'm not a professional baker by any means, but I think it's better to err on the side of caution with less kneading time and then give your dough a longer rising time before shaping the final loaf as caseoftornados says. If your dough was under-kneaded, my understanding is that the longer rise will help develop the gluten further (as it does for no-knead bread).
@gildedawn - My guess is that you're right and that you're over-kneading the dough. I actually find the windowpane test to be the least reliable of all the methods for the home baker because it's so easy to misinterpret. How is your dough with the other signs? My stand-by is usually if it holds its shape in a ball. Even if the other tests are inconclusive, this one seems to be reliable.
@KatieRoseK - It could be that you're working with a dough that has a higher proportion of water than your typical loaf of bread (typical is roughly 2 cups of water to 5-6 cups flour). I find that doughs with more water tend to stay pretty shaggy even after kneading, but they'll smooth out after rising and shaping. Does your recipe give a time estimate for kneading? If this is/was your first time making the recipe, I'd go by that and then adjust as needed the next time.