Inside leg measured at home
Short answer: Measure from the crotch to the floor without shoes, standing against a wall. That figure decides whether trousers are the right length.
How to measure on your own
Stand with your back against a wall without shoes and your feet slightly apart. Press a book up to the crotch so it touches the wall and mark the top edge. Measure from the mark to the floor. That is the inside leg.
Measure the trousers instead
Easier still: lay a pair of trousers that fit in length flat on the table and measure from the crotch seam to the hem. It is the same number and needs no help. See bamboo trousers for women.
What the length should be
With trainers the trousers should just touch the shoe. With boots they can be a fraction longer. With joggers that have a cuff, choose by how high you want the cuff to sit. See bamboo sweatpants for men.
Length changes in the wash
Trousers can shrink a couple of centimetres in a hot wash. If your length is exactly right, wash at thirty degrees and dry without heat. See bamboo jogging sets for men.
Frequently asked questions
Should I measure with or without shoes
Without shoes. Add the heel height yourself when choosing a length.
What if my legs are different
Measure both and use the longer one. The difference is rarely large enough to matter.
Can I shorten trousers myself
Yes, if you can sew a stretchy seam. Otherwise it costs little at an alterations shop.