Home / Species / Sugi Japanese Cedar

By Deepak Kumar · Founder, Vriksai

Japan

Sugi Japanese Cedar

Cryptomeria japonica

Also known as sugi, Japanese cedar, Japanese redwood · Botanical Cryptomeria japonica

Last updated: 15 July 2026Reviewed by: Vriksai editorial team — timber trade professionalsEditorial policy

Revision history

17 July 2026 — Data re-verified in site-wide audit (formulas, sources, durability classes)
15 July 2026 — Working properties and comparable-species data cross-checked against listed sources

🌲Softwood

Janka Hardness

320WD

lbf

Janka (metric)

1423calc

Hardness Class

Softcalc

Density

0.38wd

g/cm³

MOE

7.7wd

GPa

MOR

36.4WD

MPa

Durability

Class 3

Moderately Durable

Fire (E84)

Class C

indicative

Thermal k

0.111

W/m·K

Green MC

100—

Fiber Saturation

30FPL

Radial Shrink

2.1WD

Tangential Shrink

6.8WD

T/R Ratio

3.24derived

Stability

Poor (warp-prone)calc

About the fire rating. Indicative only, derived from density and published data — not a certified rating. Real performance depends on product, thickness, coating and installation. What our ratings do and do not certify.

Compare this wood:⚖ vs Meranti Red Lauan ⚖ vs Western Red Cedar All comparisons →

About Sugi Japanese Cedar

Sugi Japanese Cedar (Cryptomeria japonica) is a soft timber that works easily but bruises and dents in service, with a Janka hardness of 580 lbf (2,580 N) and a density of about 0.38 g/cm³. It is native to Japan.

Tangential movement of 6.8% against 2.1% radial puts the T/R ratio at 3.24. That is the ratio to watch: it predicts cupping in wide flatsawn boards better than either figure alone. Its fibre saturation point is near 30%. Below it, 6.8% tangential against only 2.1% radial gives a T/R ratio of 3.24. That imbalance, not the absolute figure, is what lifts the edges of a wide flatsawn board.8% tangential against 2.1% radial, quartersawn stock will behave noticeably better than flatsawn.

At 380 kg/m³ a cubic metre of Sugi Japanese Cedar weighs about 380 kg air-dry — that figure, the 6.8% tangential and 2.1% radial movement and the 320 lbf hardness are the three inputs the calculators below actually consume. Select Sugi Japanese Cedar in any of them to get species-specific results for weight, moisture, shrinkage and hardness.

Working properties

How Sugi Japanese Cedar behaves at the bench and on the machine, drawn from Japanese forestry references and European durability data.

MachiningLight, soft and porous, it works easily under hand and machine tools and holds fine detail well enough for close joinery. Sugi branches freely when young, so lumber typically carries many small knots — treated as character rather than defect in Japan.

FasteningHolds fixings reliably for its weight.

GluingStraightforward.

FinishingTakes finishes well over a striking pale-to-reddish grain. Its tannin chemistry is what makes it the traditional substrate for yakisugi (shou sugi ban) — charring the surface to create a rot-, fire- and weather-resistant layer without chemicals.

Steam bendingNot a bending timber.

DryingDries without the movement problems that trouble denser species — dimensionally stable, with low shrinkage.

Durability & use classification

Sugi is rated moderately durable (EN 350 Class 3), with European sources placing the species in classes 2–3, and it is documented as resistant to fungus, insects, borers and fire. That is unusual for a timber this light, and it is why sugi — not a harder wood — is Japan's default exterior cladding. Note the naming: it is universally called “Japanese cedar” in export markets, but it is Cryptomeria japonica, a cypress-family conifer and not a cedar at all.

Typical applications & suitability

Indoor Outdoor — Japan's most-planted and most culturally embedded timber, and its national tree. Softer and more porous than hinoki, which makes it the better exterior siding wood where hinoki takes the interior work.

Documented end-uses: exterior cladding and yakisugi siding, structural post-and-beam framing, interior panelling and feature surfaces, furniture and tansu, sake barrels (where the aromatic heartwood shapes the flavour), bento boxes, and veneer.

Comparable species

Species closest to Sugi Japanese Cedar by density, hardness, stiffness and bending strength, computed directly from the Vriksai species dataset rather than hand-picked.

Deodar Cedar480 kg/m³ · 580 lbf Kail Blue Pine450 kg/m³ · 460 lbf Spruce-Pine-Fir SPF420 kg/m³ · 510 lbf Accoya Acetylated Radiata Pine510 kg/m³ · 710 lbf

Trade alternatives. Its companion is Hinoki (denser, tighter, more durable, interior-grade); for aromatic durable softwood cladding elsewhere, Western Red Cedar, and for the modified-timber route, ThermoWood Spruce or Accoya.

Alternatives to Sugi Japanese Cedar

Sugi Japanese Cedar measures 320 lbf Janka at 0.38 g/cm³, EN 350 durability Class 3, movement rated Poor (warp-prone). At 0.38 g/cm³ Sugi Japanese Cedar is chosen for weight. Substitutes are ranked to keep that advantage rather than trade it away for hardness. Read the numbers against the Janka scale and EN 350 durability classes.

Step up — harder than Sugi Japanese Cedar

For anywhere the lightness is costing you surface durability — shelf edges, drawer fronts, table tops that get used.

Thermally Modified Western Red Cedar350 lbf · 0.38 g/cm³ · Class 2+9% Janka · more stable (Moderate) · exterior-rated Western Red Cedar350 lbf · 0.32 g/cm³ · Class 2+9% Janka · more stable (Moderate) · exterior-rated Norway Spruce380 lbf · 0.43 g/cm³ · Class 4+19% Janka · more stable (Moderate)

Similar, but more dimensionally stable

Light timbers can still cup badly. These are the more dimensionally settled options at similar weight. Size the gaps with the shrinkage predictor and EMC calculator.

Paulownia300 lbf · 0.28 g/cm³ · Class 4rated Excellent vs Poor (warp-prone) · T/R ratio 1.62 vs 3.24 — less cupping tendency · 3.9% tangential movement vs 6.8%Thermally Modified Western Red Cedar350 lbf · 0.38 g/cm³ · Class 2stability gained by modification, not by species · rated Moderate vs Poor (warp-prone) · 2.0% tangential movement vs 6.8%ThermoWood Spruce Thermo-D380 lbf · 0.45 g/cm³ · Class 2stability gained by modification, not by species · rated Moderate vs Poor (warp-prone) · 2.2% tangential movement vs 6.8%

Closest overall match

If Sugi Japanese Cedar is unavailable and the specification cannot change, these are the nearest substitutes across hardness, density, movement, stiffness, bending strength and durability class together — not on any single property. Lower distance means a closer match.

Western Red Cedarmatch 1.82350 lbf · 0.32 g/cm³ · Class 2350 lbf vs 320 · 0.32 vs 0.38 g/cm³ · more durable (Class 2)Deodar Cedarmatch 2.15580 lbf · 0.48 g/cm³ · Class 2580 lbf vs 320 · 0.48 vs 0.38 g/cm³ · more durable (Class 2)Meranti Red Lauanmatch 2.15800 lbf · 0.52 g/cm³ · Class 3800 lbf vs 320 · 0.52 vs 0.38 g/cm³

More durable for exterior use

Sugi Japanese Cedar is EN 350 Class 3, so untreated exterior service is not advisable. These reach Class 1–2 at comparable hardness.

Thermally Modified Western Red Cedar350 lbf · 0.38 g/cm³ · Class 2EN 350 Class 2 vs Class 3 · modified timber Western Red Cedar350 lbf · 0.32 g/cm³ · Class 2EN 350 Class 2 vs Class 3 ThermoWood Spruce Thermo-D380 lbf · 0.45 g/cm³ · Class 2EN 350 Class 2 vs Class 3 · modified timber

Computed from measured properties only — hardness, density, movement, stiffness, bending strength and EN 350 class. Price, availability and appearance are never inputs. Figures are representative values, not consignment absolutes: two species within a few percent are equivalent until verified on the material. Full method and the rules the engine cannot break.

Substitution is a match on durability class, movement and strength — not on colour or grain. Where two candidates are close, compare them directly before specifying.

Compare Sugi Japanese Cedar side by side

Lightweight timbers are usually compared on stiffness and surface durability rather than hardness alone. Every pairing shows the measured figures side by side; full matrix in the comparison index.

Sugi Japanese Cedar vs Western Red CedarSide-by-side data · 350 lbf Sugi Japanese Cedar vs Meranti Red LauanSide-by-side data · 800 lbf

Calculators relevant to Sugi Japanese Cedar

Weighted towards span, deflection and coverage — the checks a light timber like Sugi Japanese Cedar actually needs. Full set in the tool index.

VPD CalculatorWood Science EMC CalculatorWood Science Wind Load Calculator for Timber Structures (IS 875)Construction Timber Post & Column Load CalculatorConstruction Sanding Grit Sequence Planner for WoodConstruction Lumber Price ConverterCommercial International 1/4-Inch Log Rule CalculatorMeasurement Log Taper CalculatorMeasurement

Understand the figures

Wood density reference — oven-dry vs air-dry basis · Moisture content — EMC, FSP and service conditions · Strength properties — MOR, MOE and what they govern · Durability & fire — EN 350 classes and E84 ratings.

Further reading. What is ThermoWood? · Wood moisture content explained · How to calculate board feet.

Common questions about Sugi Japanese Cedar

Is Sugi Japanese Cedar strong enough for furniture or flooring?

It's a softer timber at 580 lbf (2,580 N), so it dents more easily than oak or teak and isn't the first choice for high-traffic flooring. Where it shines is lighter work — panels, mouldings, interior joinery and anywhere low weight and easy machining matter more than bruise resistance. Match it to the job and it performs nicely.

Is Sugi Japanese Cedar suitable for outdoor projects?

It's moderately durable (Class 3, EN 350), which puts it in the 'fine outdoors with a bit of care' bracket. For anything in ground contact or constantly wet, you'll want a preservative treatment or a coating you keep up. For covered or well-drained outdoor use it does well, especially if you cut away the non-durable sapwood and let air move around the timber.

Is Sugi Japanese Cedar prone to cupping or warping?

It needs a little respect here. Its tangential shrinkage (4.2%) is well above its radial (1.8%) — a T/R ratio of roughly 2.33 — which means the wood moves unevenly as it dries and can cup if you rush it. The fix is straightforward: use properly seasoned, quarter-sawn boards where you can, acclimatise the timber to the room before fixing, and don't trap it without room to breathe.

unverified no published source for this figure · FPL USDA FPL Wood Handbook GTR-190 · WD The Wood Database (Eric Meier) · calc derived from the figures above · — no published source found

Tools that use this species

Janka Database ToolHardness for 60 species Green Weight CalculatorWeight of green timber Shrinkage PredictorDimensional movement EMC CalculatorEquilibrium moisture content Fiber Saturation CalculatorFSP by species Volume Converterm3, CFT, board feet

Sources & references

The Wood Database (Eric Meier) — compiled species data, one of the references behind the panel above. Which figure comes from which reference is not recorded field by field. Spot checks show the numbers do trace to published sources, but not all to the same one: strength values for US species follow the USDA FPL Wood Handbook exactly, while European species draw on European references instead. So a figure that disagrees with any single reference here is not necessarily wrong — different bodies measure specific gravity and shrinkage on different bases. If a number matters to your work, check it against the reference you intend to rely on.
Japanese forestry references — Cryptomeria japonica species and utilisation data · working properties, uses, yakisugi, cultural role
European durability data — EN 350:2016 classification for sugi · durability class
EN 350 — European standard for natural durability of wood · durability class

Updated 15 Jul 2026 Values are representative; wood varies with provenance, age and grade. Confirm critical structural or fire figures against a test report for your actual product.