6x6 Lumber Dimensions
Heavy square timber for structural posts and ground-contact work. Above this size it is normally bought rough-sawn rather than dressed.
Quick specificationwhat the size actually measures
| Nominal size | 6 × 6 in (152.4 × 152.4 mm) |
|---|---|
| Actual size (dry) | 5.5 × 5.5 in (139.7 × 139.7 mm) |
| Actual size (green) | 5.5625 × 5.5625 in (141.29 × 141.29 mm) |
| Dressed section area | 30.25 in² (195.16 cm²) |
| Removed per face | 0.25 in off the thickness, 0.25 in off the width |
| Trade group | Timber |
Dimensionsnominal against dressed, and why they differ
The nominal figure of 6 × 6 inches describes the rough green board. After drying and planing on four faces the section measures 5.5 by 5.5 inches — that is, 0.25 inch off each of the wide faces and 0.25 inch off each edge.
Every page in this database is generated from the dressed figure, because that is the section that has to carry the load and take the fixing. If you are sizing a beam, checking a fixing length or estimating a delivery, use 5.5 × 5.5 inches (139.7 × 139.7 mm) rather than the nominal call size.
By lengthboard feet, volume and weight for each tabulated length
| Length | Board feet | Actual volume | Weight (Spruce (Sitka)) |
|---|---|---|---|
| 6x6x6 | 18 | 1.2604 ft³ | 33.83 lb |
| 6x6x8 | 24 | 1.6806 ft³ | 45.11 lb |
| 6x6x10 | 30 | 2.1007 ft³ | 56.39 lb |
| 6x6x12 | 36 | 2.5208 ft³ | 67.67 lb |
| 6x6x14 | 42 | 2.941 ft³ | 78.95 lb |
| 6x6x16 | 48 | 3.3611 ft³ | 90.23 lb |
Two different bases, deliberately. Board feet is calculated from the nominal section, because that is the pricing convention. Volume and weight use the actual section, because that is the material actually present. A 2x4x8 is 5.33 board feet but only 1.6806 cubic feet.
Weight by speciesthe same section, every species in the database
Wood database| Species | Density | 6x6x8 weight |
|---|---|---|
| Balsa | 0.16 g/cm³ | 16.79 lb · 7.62 kg |
| Cedar (Western Red) | 0.37 g/cm³ | 38.82 lb · 17.61 kg |
| Poplar (Yellow) | 0.42 g/cm³ | 44.06 lb · 19.99 kg |
| Basswood | 0.42 g/cm³ | 44.06 lb · 19.99 kg |
| Redwood | 0.42 g/cm³ | 44.06 lb · 19.99 kg |
| Spruce (Sitka) | 0.43 g/cm³ | 45.11 lb · 20.46 kg |
| Cedar (Eastern Red) | 0.47 g/cm³ | 49.31 lb · 22.37 kg |
| Hemlock (Western) | 0.47 g/cm³ | 49.31 lb · 22.37 kg |
| Cypress (Bald) | 0.48 g/cm³ | 50.36 lb · 22.84 kg |
| Fir (Douglas) | 0.53 g/cm³ | 55.6 lb · 25.22 kg |
| Pine (Southern Yellow) | 0.55 g/cm³ | 57.7 lb · 26.17 kg |
| Mahogany (Honduran) | 0.55 g/cm³ | 57.7 lb · 26.17 kg |
| Cherry (Black) | 0.56 g/cm³ | 58.75 lb · 26.65 kg |
| Larch | 0.58 g/cm³ | 60.85 lb · 27.6 kg |
| Teak | 0.63 g/cm³ | 66.1 lb · 29.98 kg |
| OSB (Oriented Strand Board) | 0.65 g/cm³ | 68.19 lb · 30.93 kg |
| Walnut (Black) | 0.66 g/cm³ | 69.24 lb · 31.41 kg |
| Ash (White) | 0.67 g/cm³ | 70.29 lb · 31.88 kg |
| Birch Plywood | 0.68 g/cm³ | 71.34 lb · 32.36 kg |
| Birch (Yellow Birch) | 0.69 g/cm³ | 72.39 lb · 32.84 kg |
| Bamboo | 0.7 g/cm³ | 73.44 lb · 33.31 kg |
| Maple (Hard Maple) | 0.705 g/cm³ | 73.96 lb · 33.55 kg |
| Beech (American) | 0.72 g/cm³ | 75.54 lb · 34.26 kg |
| Oak | 0.75 g/cm³ | 78.69 lb · 35.69 kg |
| MDF (Medium Density Fibreboard) | 0.75 g/cm³ | 78.69 lb · 35.69 kg |
| Hickory | 0.82 g/cm³ | 86.03 lb · 39.02 kg |
| Rosewood (East Indian) | 0.85 g/cm³ | 89.18 lb · 40.45 kg |
| Ipe | 1 g/cm³ | 104.91 lb · 47.59 kg |
Weights are derived, not quoted: density at about 12% moisture content × actual volume. Treat them as a floor — green stock stays heavier until it dries.
Where it is usedtypical applications for this section
Frequently asked questionsabout 6x6
What are the actual dimensions of a 6x6?
5.5 × 5.5 inches — 139.7 × 139.7 millimetres. The nominal call size of 6 × 6 inches is the rough green section, before planing and drying.
How much does a 6x6 weigh?
That depends on the species and the length, which is why this page gives both rather than one figure. A 6x6x8 of Spruce (Sitka) weighs about 45.11 lb (20.46 kg); the table above covers every species in the database at that length.
Is a green 6x6 the same size?
No — unseasoned stock is dressed to 5.5625 × 5.5625 inches, slightly larger, because it shrinks to the dry size as it seasons. Mixing green and dry material in the same assembly will show a step once the green pieces dry.
How do I convert a 6x6 to board feet?
Multiply the nominal thickness, width and length in inches and divide by 144. For a 6x6x8 that is (6 × 6 × 96) ÷ 144 = 24 board feet.