0.8 to 2% for PA6, the widest and largest contraction band of any material on this site. Across 100 mm a part can finish anywhere from 99.2 mm to 98 mm.
Two millimetres of error across a hand-sized part is not a tolerance problem. It is a different part.
The band varies by grade
- PA6 — 0.8 to 2%, the worst
- PA612 — 0.6 to 1.4%
- PA12 — 0.5 to 1.2%, the most dimensionally stable of the unfilled nylons and the reason it is chosen for fitted parts
- PA6-CF — 0.2 to 0.6%, because chopped fibre restrains the matrix
- PA6-GF — 0.3 to 0.8%
The gap between PA6 and PA6-CF is the largest filler effect in the whole materials table, and it is why nearly all engineering nylon printing is done in a filled grade.
Moisture moves the dimension after printing
This is the part that makes nylon genuinely difficult. Nylon absorbs water from the air, and an absorbed part swells. A component measured correct on the day it came off the plate can be measurably larger a fortnight later in a humid room.
So a compensation factor derived from a fresh measurement describes a part that no longer exists. For anything with a real fit requirement, condition the part — let it reach equilibrium with the environment it will live in — and measure it then.
Compensating anyway
Model a 100 mm dimension at 100.8065 mm at the low end, or 102.0408 mm at the high end. Corrections of 0.8065 and 2.0408 mm.
The spread between those two is itself larger than PLA's entire contraction. Picking the middle is not a strategy; measuring is.
The practical route
Print in a filled grade, keep the filament dry through the whole print, condition the finished part, and design fits that tolerate movement — a slot rather than a hole, a clamp rather than an interference fit.
That is a design response to a material property, and it works far better than chasing scale factors.
Feed a conditioned measurement into the shrinkage calculator — a fresh one will not describe the part a fortnight later. The grade-by-grade bands are on the PA6 and PA12 pages.