How to shape dough

Practice, practice, practice. That's the only way you learn shaping.

I find the biggest help to get consistent loaves is to weigh the pieces of dough. If they are all the same size, then it's easier to shape consistently.

Shaping for loaf pans is just the very beginning too. Once you get the hang of it, there's a whole world of shapes to conquer, as the Formes de pains website demonstrates.

My normal trick is not to use loaf pans, or only use 'em when baking dough that doesn't need to be shaped. Or use french loaf pans, where I don't have to worry about length.

Other than that, I'd suggest looking into getting a pastry mat with a grid on it (the ones with circles are more common, but those are mainly for pies ... the ones with a grid are useful for rectangles, and there are ones on the market with both). You can then know what size you're dealing with as you're rolling things out. If you can't easily get one, then refer to a ruler, or use the pan itself as a guide.

You want to roll out a rough rectangle, with the short end being slightly smaller than the longer side of the pan -- aim for about 10 to 20% shorter. You then either fold it in on itself, or just roll the whole thing into a log.** Pinch the seams closed, and then drop it into the prepared pan, seam-side down.

Once you let it do its final proofing, it will have filled back out to the size of the pan.

** Folding will result in less of a dome, but can require more effort so that you don't end up too wide to fit in the pan easily. You may want to do a few rolled, and then once you're comfortable, try folding.

Practice?

You can make a dead dough (that is: dough with no yeasts nor leaveners) to shape them, check how they fit in the pan, and then shape them as a ball to start the process again. You can also do it with normal dough, having in mind that after several reshapings it won't rise too much.

Roll or pull your dough into a rectangle big enough to make it about 2cm (just less than 1") thick. Place your loaf tin along the top long edge.

Fold the short ends in so that the rectangle is just narrower than the tin. Now roll the dough up from the bottom edge, pressing the leading edge in with your thumbs so the rolling part of the dough has some tension.

When you get to the end of the dough, pick it up and place it in the tin seam side down to prevent it opening again. Cover, prove and bake as normal.