Take up jeans that are too long

Wash and dry the jeans the way you normally will before you measure or cut anything. Denim shrinks the first time it is wet, and cloth hemmed before it shrinks draws up short in the first wash and leaves the leg the wrong length.

Put the jeans on with the shoes you will wear with them, and fold each leg under until the bottom sits where you want it, with a little break over the shoe. Mark that new bottom edge right around the leg with chalk or a line of pins; this marked line is the finished hemline, the crease the hem will fold on, not a cut line.

Take the jeans off and turn them inside out. Below the marked line, measure down 3 cm (1 1/4 in) and mark a second line parallel to it; this lower line is where you will cut. Keep the full 3 cm rather than trimming close, because wide, whole edges let you let the jeans down again later while a skimped edge cannot be altered.

Cut across each leg along the lower line, keeping the cut straight and square to the side seams. On denim, mark the line with a ruler and follow it; the surest way to know a line is straight and on-grain is to pick up one crosswise thread and cut along the drawn line it leaves.

Check that both legs will finish the same length before you go further. Lay them together and measure from a fixed point, the crotch seam or the knee, down to the cut edge on each leg, and trim the longer one to match.

Denim frays hard at a raw edge, so lock the cut edge before you fold it. Thread the needle, knot the end, and overcast the raw edge with slanting stitches about 3 mm (1/8 in) deep, working on the inside of the leg.

Fold the allowance up to the inside along the marked finished line, so the overcast edge turns under and the crease falls exactly on that line. Pin it every few centimetres and check that the fold is even all the way round, so the leg finishes level.

Press the fold flat with a warm iron so it holds its crease while you stitch. Pressing as you go is part of the sewing, not an extra; a fold set now stitches far straighter than one held by pins alone.

If you are stitching by machine, test first: stitch across a doubled scrap of the same denim and look at both sides, tightening the upper tension a little at a time for the heavy cloth, before you touch the leg.

Stitch the hem down through all layers, working a row about 1 cm (3/8 in) above the folded edge, right around the leg. By hand, use a backstitch, which is the strongest hand stitch and takes the place of machine stitching, set about 3 mm (1/8 in) long; by machine, sew the line you tested.

Fasten off the thread with several small stitches worked one over another and hidden on the inside of the hem, so the row cannot pull loose in the wash. Go slowly where the thick side seams cross the hem, because several layers of denim are hard to pierce and forcing the needle there bends or snaps it; a thimble helps you push through.