Lumber Dimensions Chart

Buying lumber shouldn’t feel like solving a math puzzle. But when you grab a 2×4 and measure it at 1.5″ x 3.5″, confusion sets in fast.

This lumber dimensions chart guide clears up the sizing mystery once and for all. You’ll learn why nominal sizes don’t match actual dimensions, plus get the exact measurements you need for accurate project planning.

Why Lumber Sizes Don’t Match What You Expect

Walk into any hardware store and you’ll see boards labeled as 2×4, 2×6, or 1×6. These are nominal lumber sizes – the dimensions of the board when it was first cut at the sawmill.

Here’s the catch: After cutting, lumber goes through drying and planing. The wood loses moisture and gets smoothed on all sides. This process removes about 1/4” to 1/2” from each face, giving you the actual lumber dimensions that arrive at your project site.

A 2×4 actually measures 1.5” x 3.5“. A 1×6 comes in at 3/4″ x 5.5“. According to the National Institute of Standards, these standardized lumber measurements have been industry practice since the 1960s to ensure consistent quality and performance.

Complete Lumber Dimensions Chart Nominal to Actual Sizes

This comprehensive lumber size chart covers every common dimension you’ll encounter. Use these actual measurements when planning cuts, building frames, or ordering materials.

Standard Dimensional Lumber Sizes

Decking and Specialty Lumber

Decking boards follow the same pattern but use different thickness designations:

The 5/4 decking is the most popular choice for outdoor projects. It provides better durability than standard 1-inch boards while staying cost-effective.

Lumber Sizing From Sawmill to Store

Green lumber comes straight from the sawmill with high moisture content – often 50% or more water by weight. Fresh-cut timber needs processing before it’s ready for construction or woodworking.

The drying process is where size reduction happens. Lumber loses10-15% of its dimensions as moisture evaporates. Kiln-dried lumber reaches 6-8% moisture content, making it stable and ready for finish planing.

Surface planing smooths out saw marks and creates uniform boards. Each pass through the planer removes approximately 1/16” to 1/8” from the surface. When all four sides get planed (called S4S lumber), you end up with the finished dimensions you see on the chart.

This standardization started in 1964 when the American Lumber Standards Committee established PS 20 standards. These rules ensure every 2×4 measures the same, whether you buy it in Texas or Maine.

How to Calculate Lumber Dimensions for Your Project

Always use actual dimensions when measuring for cuts or calculating materials. This single step prevents the most common DIY mistakes and material waste.

Measure twice, cut once takes on new meaning with lumber. If your plan calls for a4-foot wall frame, don’t assume eight 2×4 studs at 6 inches apart will work. Those studs are really 3.5” wide, not 4“.

Board foot calculations also need actual measurements. The formula is: (Thickness in inches × Width in inches × Length in feet) ÷ 12. For a 2×6 that’s 8 feet long: (1.5 × 5.5 × 8) ÷ 12 = 5.5 board feet.

Common ordering mistakes happen when builders forget the difference. Ordering 100 nominal 2x4s for a job calculated with actual dimensions leaves you short on materials and over budget.

Lumber Length Standards and Tolerances

Standard lumber lengths come in 2-foot increments: 6, 8, 10, 12, 14, 16, 18, 20, 22, and24 feet. Some suppliers stock 26-foot boards, but availability varies by region.

Length accuracy is different from width or thickness. According to NIST PS 20 standards, lumber must be at least the nominal length. Most mills cut boards 1-3 inches over to account for end trimming and damage.

A 10-foot board typically measures 10 feet or slightly longer. You might get 10’1″ or even 10’3″. This extra length gives you flexibility for square cuts and helps eliminate damaged end sections.

Hardwood lumber follows different rules than softwood. Hardwoods are often sold in random lengths and widths, with pricing based on board footage rather than linear feet. Premium hardwood suppliers mill to tighter tolerances – within 1/32″ for thickness.

Conclusion

Lumber dimensions chart for quick reference. Understanding the difference between nominal and actual lumber sizes saves time, money, and frustration at the hardware store. Whether you’re framing a wall or building furniture, always measure with actual dimensions for professional results.

FAQs

What are standard lumber sizes?

Standard lumber sizes include 1x, 2x, 4x, and 6x boards in various widths. The most common are 2×4, 2×6, 2×8, and 2×10 for framing lumber. These nominal dimensions represent rough-cut measurements before drying and planing. Actual finished sizes are consistently smaller – a 2×4 measures 1.5″ × 3.5″, while a 2×10 comes in at 1.5″ × 9.25″. Length options range from 6 to 24 feet in 2-foot increments, with 8, 10, and 12-foot boards being the most widely stocked.

What will fresh cut green lumber do as it dries?

Fresh-cut green lumber will shrink, warp, and lose significant moisture content as it dries. Wood can contain more than 50% water by weight when first cut, and this moisture evaporates over time. Expect dimensional changes of 6-10% across the grain and 2-4% along the length.

What is the dimension of a 2×8?

A 2×8 lumber board measures 1.5 inches thick by 7.25 inches wide in actual dimensions. The nominal 2×8 size refers to rough-cut measurements before the board was dried and planed. This is one of the most popular framing lumber sizes for floor joists, headers, and beams.

Is 10 ft lumber actually 10 ft?

Yes, 10-foot lumber is actually 10 feet long or slightly longer. Unlike width and thickness, length measurements hold true to their nominal size. Industry standards require lumber to be at least the stated length, with most mills adding 1-3 inches extra.