Balsam fir is a small to medium-size
evergreen tree typically 14–20 metres (46–66 ft) tall, rarely to 27 metres (89 ft) tall, with a narrow conic crown. The
bark on young trees is smooth, grey, and with
resinblisters (which tend to spray when ruptured), becoming rough and fissured or scaly on old trees. The
leaves are flat needle-like, 15 to 30 millimetres (½–1 in) long, dark green above often with a small patch of
stomata near the tip, and two white stomatal bands below, and a slightly notched tip. They are arranged spirally on the shoot, but with the leaf bases twisted to appear in two more-or-less horizontal rows. The
cones are erect, 40 to 80 millimetres (1½–3 in) long, dark purple, ripening brown and disintegrating to release the winged
seeds in September.