Board Size Calculator
Pick the nominal thickness and width, enter the length and how many boards you need. The calculator shows the real size after drying and planing, the board feet and the cost at your price.
- Actual lumber size
- Board feet
- Cost per order
Board feet are worked from the nominal size, which is how lumber yards price it.
A 2 × 4 is not 2 inches by 4 inches. Nominal sizes name the rough-sawn board before it dries and is planed smooth. A 2 × 4 ends up 1 1/2 × 3 1/2 in, and a 2 × 10 is 1 1/2 × 9 1/4 in. Board feet still use the nominal size, so an 8 ft 2 × 6 is 8 board feet.
Nominal and actual lumber sizes
Softwood dimension lumber. Search for a size.
| Nominal | Actual (in) | Actual (mm) | Board feet in 8 ft |
|---|---|---|---|
| 1 × 4 | 0.75 × 3.5 | 19 × 89 | 2.67 |
| 1 × 6 | 0.75 × 5.5 | 19 × 140 | 4 |
| 1 × 8 | 0.75 × 7.25 | 19 × 184 | 5.33 |
| 2 × 4 | 1.5 × 3.5 | 38 × 89 | 5.33 |
| 2 × 6 | 1.5 × 5.5 | 38 × 140 | 8 |
| 2 × 8 | 1.5 × 7.25 | 38 × 184 | 10.67 |
| 2 × 10 | 1.5 × 9.25 | 38 × 235 | 13.33 |
| 2 × 12 | 1.5 × 11.25 | 38 × 286 | 16 |
| 4 × 4 | 3.5 × 3.5 | 89 × 89 | 10.67 |
| 4 × 6 | 3.5 × 5.5 | 89 × 140 | 16 |
| 6 × 6 | 5.5 × 5.5 | 140 × 140 | 24 |
Board feet are for an 8 ft length.
Width and board feet
2 in boards, 8 ft long. Slide the nominal width.
The dashed outline is the nominal size and the solid board is what you actually get.
How to work out board size
From name to real size. Step through it.
Read the name
Thickness × width.
Rough-sawn and hardwood boards keep closer to their full size, so check before you plan tight joints.
Dimension, hardwood or metric
How boards are sold. Compare them.
US softwood.
Furniture boards.
UK and Europe.
Metric timber in the UK and Europe is often sold by its finished size, such as 47 × 100 mm, which is close to a 2 × 4.
Before you buy
Order checks. Tick each item.
Tick each item as you go.
Buy a few extra boards for cutting waste, knots and the odd twisted piece.
What you get
Lumber sizing. Each tile explains one result.
Inches.
Millimetres.
Each and total.
At your price.
From planing.
Prices per board foot let you compare boards of different sizes fairly.
Frequently Asked Questions
No question matches that search.
What is the actual size of a two by four?
One and a half inches by three and a half inches.
Why are lumber sizes smaller than their names?
The name is the rough-sawn size. Drying and planing take about half an inch off each side measurement.
How do I calculate board feet?
Multiply the nominal thickness and width in inches by the length in feet, then divide by twelve.
What is the actual size of a two by ten?
One and a half by nine and a quarter inches.
Is a four by four really four inches?
No. It is three and a half inches square.
Do board feet use actual or nominal size?
Nominal size, which is how lumber is priced.
What is a board foot?
A volume of wood one foot square and one inch thick, or 144 cubic inches.
Plan with the real size
Draw and cut with the actual dimensions, and price with board feet. Then order a little extra for waste.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.