Does Cedar Shrink When It Dries? Yes, About 6.8%
Cedar shrinks about 5-7% in volume as it dries from green to oven-dry, and that movement is uneven — roughly twice as much across the growth rings (tangential) as toward the center (radial). A 6-inch-wide Western red cedar board can lose close to 3/16 inch in width going from green to a stable 8-10% moisture content. This guide covers the exact shrinkage numbers by species, how it compares to oak and pine, and how much gap to leave in decking and siding so the wood doesn’t buckle or crack.
How Much Does Cedar Actually Shrink?
Western red cedar shrinks 2.4% radially, 5.0% tangentially, and about 6.8% in total volume, measured from green (freshly cut) to oven-dry, according to the USDA Forest Products Laboratory’s Wood Handbook and the Wood Database’s species data. Eastern red cedar is close behind at 3.1% radial and 4.7% tangential. Those are the real, sourced figures — not the vague “5-10%” or “2-4%” ranges that get repeated around the web without a source.
The tangential direction (the growth rings, running around the tree’s circumference) always shrinks more than the radial direction (a line straight out from the center). That’s why flatsawn boards cup and warp more than quartersawn boards of the same species — the two faces of a flatsawn board are shrinking at different rates relative to the growth rings.
Cedar vs Other Woods: Shrinkage Compared
Cedar is one of the most dimensionally stable woods you can build with. Here’s how it stacks up against common comparison species, green-to-oven-dry:
| Wood Species | Radial Shrinkage | Tangential Shrinkage | Volumetric Shrinkage |
|---|---|---|---|
| Western Red Cedar | 2.4% | 5.0% | 6.8% |
| Eastern Red Cedar | 3.1% | 4.7% | 7.8% |
| Eastern White Pine | 2.1% | 6.1% | 8.2% |
| Northern Red Oak | 4.0% | 8.6% | 12.6% |
| White Oak | 5.6% | 10.5% | 16.1% |
| Sugar Maple | 4.8% | 9.9% | 14.7% |
Source: USDA Forest Products Laboratory Wood Handbook and Wood Database species data. Cedar’s volumetric shrinkage is roughly half that of white oak, which is exactly why it stays flatter and gaps less than hardwoods when used outdoors in decking or fencing.
Why Cedar Shrinks as It Dries
Freshly cut (“green”) cedar can hold 30% or more moisture by weight inside its cell walls. As it dries, water first leaves the empty cell cavities with no dimensional change at all — the wood only starts shrinking once moisture drops below the fiber saturation point, roughly 28-30% moisture content (MC). Below that point, the cell walls themselves lose bound water and physically contract.
A commonly used engineering rule of thumb is that wood changes about 1/30 (roughly 0.1-0.2%) of its total tangential shrinkage for every 1% change in moisture content below the fiber saturation point. For cedar’s 5.0% tangential shrinkage, that works out to roughly 0.17-0.2% dimensional change per 1% MC swing — small per point, but it adds up across a full drying cycle from 30% down to an 8% equilibrium moisture content (EMC), which is typical for cedar used outdoors in most US climates (interior cedar typically stabilizes closer to 6-8% MC as well). Use our wood shrinkage calculator to estimate the dimensional change for your own board’s starting and target moisture content.
Air-Drying vs Kiln-Drying: Does the Method Change the Shrinkage?
No — the total shrinkage percentage is the same either way, because it’s driven by final moisture content, not drying speed. What changes is how evenly the wood dries:
- Air drying: Cedar stacked outdoors with stickers between layers for airflow typically takes 6-12 months to reach 12-15% MC, and longer to fully equalize. Slower drying reduces the risk of surface checking because the outside and inside of the board dry at closer rates.
- Kiln drying: Controlled heat and humidity bring cedar down to a target 6-8% MC in days rather than months. Done correctly this doesn’t increase total shrinkage, but a kiln run too hot or fast can dry the surface faster than the core, causing checking and case-hardening.
Most cedar sold as dimensional lumber at home centers is kiln-dried and sold “S-DRY” or “KD19” (19% MC or less) — check the grade stamp. If you’re working with green or air-dried cedar lumber, budget for the shrinkage before you cut final joinery.
How to Check Your Cedar’s Moisture Content Before You Build
The only reliable way to know if a board has finished shrinking is to measure its moisture content directly, not guess by feel or weight. A pin or pinless moisture meter reads MC in seconds — if the reading is still above 12-15%, expect more movement before the piece is dimensionally stable.
Best Moisture Meter Pick
General Tools MMD4E Moisture Meter
A pin-type meter that reads moisture content directly in the wood, with separate scales for softwoods like cedar.
- Best for: checking cedar boards and framing before final joinery or install
- Why we picked it: accurate, budget-friendly, and simple enough for a one-time project
- Main drawback: pins leave small marks, so test on an offcut or hidden face
Compare more moisture meter options
 Option 1 Klein Tools ET140 Pinless Meter
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 Option 2 TopTes TS-630 Digital Meter
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 Option 3 Mecurate Pin Type Meter
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How Much Gap to Leave for Shrinkage
For a 6-inch-wide cedar deck board or fence picket, going from a typical 19% kiln-dried MC down to an 8% outdoor equilibrium is an 11-point moisture drop. Using cedar’s ~0.17-0.2% tangential shrinkage per 1% MC, that board will lose roughly 3/32 to 1/8 inch in width as it finishes drying in place. That’s the real-world reason installers leave a gap, not just a rule of thumb with no basis:
- Deck boards: 1/8 to 3/16 inch between boards if the cedar is already kiln-dried and acclimated; up to 1/4 inch if it’s installed green or air-dried.
- Fence pickets: a nickel’s width (about 1/16 inch) is the common trade rule for kiln-dried picket stock; wider for green lumber.
- Siding laps: follow the manufacturer’s minimum overlap — cedar siding installed too tight against itself will buckle as it equalizes to outdoor humidity.
What Shrinkage Means for Joinery and Finishing
In furniture and cabinetry, cedar’s movement is small compared to oak or maple, but it’s not zero. A mortise and tenon joint cut from cedar that was still at 15% MC can loosen slightly once the piece reaches an indoor equilibrium of 6-8% MC. Cut joinery from stock that’s already acclimated to the room it will live in, and orient panels so the wide faces can move without splitting a glued edge.
A film-forming finish like polyurethane slows moisture exchange and reduces the day-to-day swings that cause surface checking, but it does not stop the wood from reaching its final equilibrium moisture content — it just gets there more slowly and evenly. Penetrating oil finishes offer less of that buffering but let the wood breathe, which matters more for outdoor cedar than for finished furniture.
Frequently Asked Questions
Does cedar shrink a lot when it dries?
No. Cedar shrinks about 6.8% in total volume from green to oven-dry, roughly half the shrinkage of white oak (16.1%) or sugar maple (14.7%). That makes it one of the more dimensionally stable woods available for outdoor projects.
How much does cedar wood shrink in width?
Across the growth rings (tangential), Western red cedar shrinks about 5.0% from green to oven-dry. On a 6-inch-wide board drying from a typical 19% kiln-dried moisture content down to an 8% outdoor equilibrium, that works out to roughly 3/32 to 1/8 inch of width loss.
What causes cedar to shrink?
Cedar shrinks when moisture inside the wood’s cell walls drops below the fiber saturation point, around 28-30% moisture content. Above that point, water leaving the wood causes no dimensional change; below it, the cell walls physically contract as they lose bound water.
Can you prevent cedar from shrinking?
You cannot prevent shrinkage entirely, but you can control when and how evenly it happens. Buy kiln-dried cedar already at 12-19% MC, let it acclimate to its final environment for at least a week before cutting joinery, and check moisture content with a meter rather than guessing.
Does kiln-dried cedar still shrink after installation?
Yes, a small amount. Kiln-dried cedar is typically sold at 12-19% MC, but outdoor equilibrium moisture content in most US climates is closer to 8-12%. Expect a further 1-2% of tangential movement as the wood finishes settling into its installed environment.
Conclusion
Cedar does shrink as it dries — about 6.8% in total volume for Western red cedar, roughly half the movement of white oak or maple. Check moisture content with a meter before cutting final joinery, leave a 1/8 to 3/16 inch gap between deck boards or pickets, and let kiln-dried stock acclimate for at least a week before installation. Cedar’s low shrinkage is exactly why it stays flatter and cracks less than hardwoods in fencing and decking projects.
