CutMath

Balsam Fir

Abies balsamea · softwood · Northeastern North America · moderate movement

Field data
  • Janka hardness 400 lbfred oak ≈ 1,290 lbf
  • Density ≈ 24 lb/ft³specific gravity 0.35 at 12% MC
  • Shrinkage — tangential 6.9%flatsawn width, green → ovendry
  • Shrinkage — radial 2.9%quartersawn width
  • T/R ratio 2.4 : 1higher = more cupping in flatsawn stock

Shop notes Light SPF-mix construction lumber; low stiffness, frequent knots. Utility work, not furniture.

Seasonal movement at a glance

Width change for balsam fir across a typical indoor year — 6% moisture content in the heated winter to 12% in a humid summer:

Board widthFlatsawnQuartersawn
6″ 3/32″ (0.089″) 1/32″ (0.037″)
12″ 3/16″ (0.177″) 1/16″ (0.075″)
24″ 11/32″ (0.355″) 5/32″ (0.149″)
36″ 17/32″ (0.532″) 7/32″ (0.224″)

Run your own numbers

Different width, different climate swing — the calculator below is preset to balsam fir:

Board & conditions
Grain
Conditions given as

Typical swings:

Movement estimate
    Estimate Figures use species-average shrinkage from the USDA Wood Handbook and the standard shop movement formula. Individual boards vary — leave margin, especially with flatsawn stock.

    Balsam Fir questions

    How much does balsam fir move with the seasons?

    A 12″-wide flatsawn balsam fir board moves about 3/16″ across a typical indoor swing from 6% to 12% moisture content; quartersawn, about 1/16″. Its tangential shrinkage is 6.9% and radial 2.9% (green to ovendry) — a moderate-movement wood.

    How hard is balsam fir?

    Balsam Fir rates about 400 lbf on the Janka scale — soft enough to dent in daily use (red oak is roughly 1,290 lbf). Density runs about 24 lb/ft³ at indoor moisture levels.

    Is balsam fir good for wide panels and tabletops?

    Carefully. Its tangential-to-radial ratio of 2.4:1 makes flatsawn boards prone to cupping — choose quartersawn stock for wide glue-ups, alternate growth rings, and fasten tops so they can slide.

    Similar species

    Noble Fir · Engelmann Spruce · Eastern White Pine · Western White Pine · Sugar Pine · Pacific Silver Fir

    Shrinkage, specific gravity, and hardness from the Wood Handbook, FPL-GTR-282 (2021 edition), USDA Forest Products Laboratory (public domain). Values are species averages — individual boards vary with growth conditions and how they were dried.