How do you calculate how many boards I will need?

Quick Answer

Calculating how many boards you will need for a project requires a few key steps:

  1. Measure the area you need to cover in square feet
  2. Determine the board size you plan to use (e.g. 1×4, 2×4, etc.)
  3. Calculate the square footage of each individual board
  4. Divide the total area by the area of each board to get the estimated number of boards needed
  5. Add 10-20% more boards to account for cutting waste and defects

Measuring the Area to Cover

The first step in figuring out how many boards you need is to accurately measure the area you need to cover in square feet. Here are some tips for getting accurate measurements:

  • Use a laser distance measurer or tape measure for precision
  • Measure length x width to calculate area for rectangular spaces
  • For irregular shapes, divide into rectangles/squares and add together
  • Round up measured lengths to the nearest whole foot
  • Multiply length x width of each rectangle for its area
  • Add together areas of multiple spaces if covering separate sections

Always overestimate rather than underestimate the area to ensure you purchase enough material. It’s better to have a few extra boards than to run out halfway through a project.

Example Area Measurement Calculation

Say you need to cover a 10 ft x 12 ft shed floor and a 3 ft x 5 ft worktable.

  • Shed floor = 10 ft x 12 ft = 120 sq ft
  • Worktable = 3 ft x 5 ft = 15 sq ft
  • Total area = 120 sq ft + 15 sq ft = 135 sq ft

So for this example project, the total area needed to cover is 135 square feet.

Choosing Your Board Size

Once you know the total square footage you need to cover, the next step is choosing what size boards you plan to use for the project. Common board size options include:

Board Name Board Dimensions
1×2 3/4 in x 1-1/2 in
1×3 3/4 in x 2-1/2 in
1×4 3/4 in x 3-1/2 in
1×6 3/4 in x 5-1/2 in
1×8 3/4 in x 7-1/4 in
1×10 3/4 in x 9-1/4 in
1×12 3/4 in x 11-1/4 in
2×2 1-1/2 in x 1-1/2 in
2×4 1-1/2 in x 3-1/2 in
2×6 1-1/2 in x 5-1/2 in
2×8 1-1/2 in x 7-1/4 in
2×10 1-1/2 in x 9-1/4 in
2×12 1-1/2 in x 11-1/4 in

Choose a board size appropriate for your project – thicker boards are more rigid and durable. For a floor or deck, use at least 1×6 boards. For furniture, 1×3 or 1×4 may suffice.

Figuring Square Footage per Board

Once you know the dimensions of the boards you’ll be installing, the next step is to calculate the square footage of each individual board:

  • Board width x board length = square footage per board

For example:

  • A 1×4 board is 3.5 inches wide x 1.5 inches thick
  • In feet: 3.5 inches = 0.2917 feet wide
  • 1.5 inches = 0.125 feet thick
  • 0.2917 ft x 0.125 ft = 0.0365 square feet per 1×4 board

Do the same calculation for whatever size boards you’ll be using, converting inch dimensions to feet. This gives you the square footage per board.

Board Square Footage Examples

Board Type Square Footage per Board
1×4 0.0365 sq ft
1×6 0.0625 sq ft
2×4 0.0833 sq ft
2×6 0.125 sq ft

You’ll need this square footage per board number for the final calculation.

Calculating Total Boards Needed

Now you can calculate the estimated total number of boards needed:

  • Total area (sq ft) / Board square footage = Total boards needed

Using our example:

  • Total area = 135 sq ft
  • 1×4 board = 0.0365 sq ft per board
  • 135 sq ft / 0.0365 sq ft per board = ~3,698 boards

So for a 135 sq ft area using 1×4 boards, the estimated number of boards needed is 3,698 boards.

Round up the total boards needed to the nearest whole number for your purchase quantity. It’s smart to round up to allow for extra boards.

Sample Board Quantity Calculations

Total Area Board Type Boards Needed
135 sq ft 1×4 3,698 boards
500 sq ft 2×4 6,024 boards
65 sq ft 1×6 1,040 boards

Use the same formula, inputting your measured area and board square footage to estimate total boards for your specific project.

Adding Extra Boards

When determining the final quantity of boards to purchase, be sure to add 10-20% more boards than your calculated quantity to account for:

  • Cutting waste – boards that get cut into smaller pieces
  • Defects – warped, cracked or unusable boards
  • Errors – miscuts and mistakes
  • Future repairs/replacements – extra boards leftover

It’s always better to end up with a few extra usable boards than to run short during a project. factoring in this waste allowance can prevent you from having to make extra trips to purchase more materials.

For our 1×4 board example, the final quantity with 15% added would be:

  • Calculated boards needed = 3,698 boards
  • Add 15% more boards = 3,698 x 0.15 = 554 extra boards
  • Total boards to purchase = 3,698 + 554 = 4,252 boards

Round up your total to full packages of boards when purchasing. Leave the retailer with extra unopened packages rather than running short.

Purchasing and Delivery

Once you know your board quantity needed including waste allowance, you’re ready to purchase materials. Buy from a reputable lumber retailer that allows returns on unopened packages. Here are some final tips:

  • Confirm availability – ensure the retailer has your board size and quantity in stock before purchasing
  • Schedule delivery – have materials delivered rather than transporting yourself
  • Stage boards – move delivered boards close to project area to avoid rehandling
  • Inspect materials – look through boards and set aside any warped, cracked or damaged pieces for return
  • Save receipts – keep receipts to return any unopened items

Taking these steps when buying and receiving boards will help ensure you start your project with quality materials ready to install.


Calculating the number of boards needed for projects like floors, walls, decks and furniture is straightforward once you understand the key steps:

  1. Accurately measure area in square feet
  2. Choose appropriate board size and calculate square footage per board
  3. Divide total area by board square footage to estimate needed quantity
  4. Add 10-20% extra boards to allow for waste factors
  5. Purchase, deliver and inspect materials

Following this process will help you determine an accurate board quantity to buy for your project the first time. Purchasing the right amount of boards will save you time and money by avoiding problems caused by buying too few materials.

Use these calculations as a planning estimate, not an exact amount. Cutting and installing boards will determine the final used quantity. The spare boards left over will become useful for future carpentry work or minor repairs down the road.

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