Introduction
A linear foot is simply one foot of length in a straight line. In construction, you often need to convert between square feet and linear feet when buying lumber, decking, siding, trim, or fencing. The math depends on the width of your material — a 6-inch-wide board covers more area per foot than a 4-inch-wide board. This linear feet calculator does that math for you, quickly and accurately.
Use the converter at the top to switch between square feet and linear feet based on your board width. The batch table lets you calculate multiple items at once, each with a different width, and see a running total. The width comparison section shows how many linear feet you need across several common board widths side by side, along with estimated board counts for standard 8-foot, 10-foot, and 12-foot lengths. Whether you're estimating materials for a deck, planning a fence, or pricing out trim work, this tool helps you get the right numbers before you buy.
How to Use Our Linear Feet Calculator
This calculator converts between square feet and linear feet based on your material's width. Enter your measurements below and get instant results for single conversions, batch projects, or side-by-side width comparisons.
Board / Material Width (inches): Enter the width of your board or material in inches. Common sizes include 2, 3.5, 4, 5.5, 6, 8, 10, and 12 inches. This width is used to figure out how square feet and linear feet relate to each other.
Square Feet: Enter the total square footage you need to cover. The calculator will use your width to tell you how many linear feet of material that equals. This is helpful when you know the area of a floor, wall, or deck but need to order lumber or planking by the linear foot. If you need help determining the area of your project, try our square footage calculator.
Linear Feet: If you already know the linear feet, enter that number instead. The calculator works both ways and will figure out the square footage for you. A "Calculated" badge will appear next to whichever field the tool solved automatically.
Multi-Row Batch Conversion Table: Use this section when your project has several materials or different widths. Each row lets you set its own width and square footage. The calculator adds up all rows and gives you a grand total of both square feet and linear feet. Click "Add Row" to include more items, or remove rows you no longer need.
Target Square Feet (Width Comparison): Enter the total square footage of your project in this field. The comparison table will show how many linear feet you need for every width you list, so you can pick the most cost-effective board size.
Widths to Compare: Type in a list of board widths separated by commas. The table will display the linear feet needed for each width, plus how many 8-foot, 10-foot, and 12-foot boards you would need to buy. A green row marks the width that requires the fewest linear feet, and an orange row marks the width that requires the most. A bar chart below the table gives you a quick visual comparison.
What Are Linear Feet?
A linear foot is simply a measurement of length equal to 12 inches, or one foot. Unlike square feet, which measure area (length × width), linear feet only measure how long something is in a straight line. When you buy lumber, trim, fencing, or piping, the price is often listed per linear foot. This means you are paying for the length of the material, no matter how wide or thick it is.
Why Convert Between Square Feet and Linear Feet?
In construction, you often know the area you need to cover in square feet, but the materials you buy are sold by the linear foot. For example, if you need to install flooring or decking over a 200-square-foot space using 6-inch-wide boards, you need to figure out how many linear feet of those boards to purchase. Without this conversion, you could end up buying too much or too little material, wasting money or delaying your project.
The Conversion Formula
The math behind this conversion is straightforward:
- Linear Feet = (Square Feet × 12) ÷ Width in Inches
- Square Feet = (Linear Feet × Width in Inches) ÷ 12
You multiply square feet by 12 because there are 12 inches in a foot. This converts the area into inch-based units so it can be divided evenly by the board width in inches. For instance, 100 square feet of coverage using 6-inch-wide boards requires (100 × 12) ÷ 6 = 200 linear feet of material.
How Board Width Affects Material Needs
The width of your material makes a big difference in how many linear feet you need. Wider boards cover more area per foot of length, so you need fewer linear feet. Narrower boards cover less area, so you need more. Here are some common board widths used in construction:
- 2 inches – thin strips, often used for trim or battens
- 3.5 inches – the actual width of a standard 2×4 lumber piece
- 5.5 inches – the actual width of a standard 1×6 or 2×6 board
- 6 inches – common for fencing and decking boards
- 8, 10, and 12 inches – wider planks used for sheathing, siding, or shelving
Keep in mind that lumber sizes are labeled by their nominal dimensions, not their actual dimensions. A 2×6 board is actually 1.5 inches thick and 5.5 inches wide. Always use the actual width when calculating linear feet. If you're working with lumber volume rather than length, our board foot calculator can help you estimate costs based on board foot pricing.
Tips for Accurate Material Estimates
When planning a project, it helps to add a waste factor of 5% to 10% on top of your calculated linear feet. Cuts, mistakes, and natural defects in wood mean you will almost always need more than the exact calculated amount. If you are installing boards at an angle, like a 45-degree pattern on a deck, plan for at least 15% extra material.
The calculator above also shows how many standard-length boards (8-foot, 10-foot, or 12-foot) you would need. This is helpful when placing an order, since lumber yards and home improvement stores sell boards in these fixed lengths. Choosing the right board length can reduce waste from cutoffs. For related construction projects, you may also find our framing calculator, stud calculator, or drywall calculator useful when estimating the full scope of materials needed.