The outseam is the seam running down the outside of the trouser leg, joining front and back panels from waistband to hem; it is also the outer-length measurement, taken from the top edge of the waistband along that seam down to the hem. Together with the inseam, the outseam is the measurement that governs trouser length and how the leg lands on the shoe.
What is the outseam, and how does it differ from the inseam?
Each trouser leg has two vertical seams:
- Outseam (outer seam): from waistband to hem, passing over the hip — its length includes the rise, so it reflects the total length of the trousers.
- Inseam (inner seam): from the crotch seam to the hem — measuring only the leg itself.
Outseam minus inseam equals the rise. Two pairs with identical inseams but different rises will therefore have different outseams — knowing this saves confusion when reading size charts or sending trousers for alteration. Structurally, the outseam is also where the slanted pockets sit, and it is the seam a tailor opens when the leg or hip needs letting out.
Why the outseam matters in tailoring
- It sets the trouser break: a few centimetres of outseam decide whether the hem meets the shoe with a full break, half break, or no break — a detail that directly shapes how sharp the whole suit looks.
- It keeps the leg hanging straight: an outer seam sewn off-grain or with tight thread makes the leg twist subtly around the shin, pulling the crease out of line with the shoe.
- It is the main alteration seam: widening the hip, easing the leg, or adjusting the taper is done chiefly along the outseam, where inlay is left and the crotch construction stays untouched.
- It is the best remote reference: sending the outseam of your best-fitting pair communicates length far more precisely than any verbal description.
How to measure the outseam correctly
- Lay the trousers flat on a table and smooth the leg along its crease.
- Measure from the top edge of the waistband (excluding any extended tab) along the outer seam to the bottom of the hem.
- Measure both legs — a difference beyond 0.5 cm signals imprecise making or altering.
- When measuring on the body, wear the shoes you actually pair with those trousers, since heel height shifts where the break falls.
Common mistakes about the outseam
- Confusing outseam with inseam when quoting a measurement, leaving altered trousers short or long by the entire rise.
- Changing length at the hem alone and forgetting that a tapered leg narrows at the new cut point, making the hem tighter than designed.
- Applying one fixed outseam to every pair, even though each has a different rise.
- Measuring unpressed trousers or drifting off the seam line — the accumulated error can exceed a centimetre.
A word from Mon Amie's artisans
When a client brings trousers in for length adjustment, Mon Amie's artisans always re-measure the outseam on both legs and ask him to stand in the shoes he actually wears — many men's legs differ by a few millimetres, and the hems must be cut unevenly to look even. Keep a note of the outseam of your best-fitting pair; it is the most valuable anchor for every future commission.
To have a complete, accurate set of measurements taken for your wardrobe, book an appointment with Mon Amie and learn about the tailoring process.