Wood Movement / Shrinkage Calculator
SI
Imp
Imperial
Inputs
View results
Wood species
Choose a screening shrinkage preset, or choose custom/measured stock to enter radial, tangential and FSP values directly.
Red oak
White oak
Hard maple
Soft maple
Black cherry
Black walnut
White ash
American beech
Yellow birch
Yellow poplar
Douglas fir
Southern yellow pine
Eastern white pine
Western red cedar
Spruce
Teak
Custom / measured stock
Board width across grain
(W0)
Width measured across the grain, not along the board length. Wood movement along grain is usually much smaller.
in
Initial moisture content
(MC1)
Starting wood moisture content.
% MC
Final moisture content
(MC2)
Expected equilibrium or service moisture content.
% MC
Grain orientation
(grain)
Flat-sawn boards move mostly tangentially. Quarter-sawn boards move mostly radially.
Flat-sawn / tangential
Quarter-sawn / radial
Mixed / average
Custom coefficient
Custom tangential shrinkage
(S_t)
Total tangential shrinkage from fiber saturation point to oven-dry.
%
Custom radial shrinkage
(S_r)
Total radial shrinkage from fiber saturation point to oven-dry.
%
Custom shrinkage
(S_c)
Custom total shrinkage from fiber saturation point to oven-dry.
%
Custom fiber saturation point
(FSP)
Moisture content above which dimensional change is minimal. Common first-pass value is about 28%.
% MC
Results
Default result
Edit inputs
Movement magnitude
(|dW|)
0.2211
in
Caution
shrinkage
Also computed
Final width
(W2)
11.7789
in
Signed width change
(dW)
Caution
−0.2211
in
shrinkage
Movement percent
(|dW|/W0)
1.843
%
Tangential change
(dW_t)
−0.2211
in
Radial change
(dW_r)
−0.1029
in
MC change below FSP
(dMC)
−6
% MC
Shrinkage coefficient used
(S)
8.6
%
Show 1 more results
Signed width change vs Final moisture content (%)
Movement is plotted from the entered starting moisture content to possible final moisture contents below FSP. Negative values mean shrinkage.
Signed width change vs Final moisture content (%)
−0.5
0
0.5
1
0
10
20
30
entered final MC
Final moisture content (%)
Signed width change (in)
Movement is plotted from the entered starting moisture content to possible final moisture contents below FSP. Negative values mean shrinkage.
Method notes
4 notes
Approximation: width change = width x total shrinkage x (final MC - initial MC) / fiber saturation point.
Only moisture below the fiber saturation point is used. Moisture above FSP is clamped because free water has little dimensional effect.
Species preset: Red oak (8.6% tangential, 4% radial, 28% FSP). Presets are screening values; measured stock or a species reference is better for final clearance work.
Species, grain angle, juvenile wood, reaction wood, restraint, finish, temperature and actual equilibrium moisture can shift real movement.
Powered by MachineCalcs ↗