🪵 Decking Calculator
Calculate decking boards needed for your deck project
Recommended: 1/8" (0.125") gap for drainage
How to Use This Calculator
Enter Deck Dimensions
Input the length and width of your deck in feet. Measure the deck area where you'll be installing decking boards.
Specify Board Width
Select your decking board width in inches. Standard is 5.5 inches (2×6 nominal), but boards come in various widths (3.5", 5.5", 7.25", 9.25", 11.25").
Set Gap Between Boards
Enter the gap between boards in inches. Recommended is 1/8 inch (0.125") for proper drainage. Gaps prevent water pooling and allow for wood expansion.
Calculate and Order
Click "Calculate Decking" to see boards needed, linear feet, and board feet. Add 10% extra for waste. Order decking boards based on linear feet needed.
Formula
Deck Area (sq ft) = Length (ft) × Width (ft)
Effective Width = Board Width (inches) + Gap (inches)
Boards Needed = Deck Width (inches) ÷ Effective Width
Linear Feet = Boards Needed × Deck Length (ft)
Board Feet = (Board Width × Length × Quantity) ÷ 12
Example 1: Standard Deck (20 ft × 12 ft, 5.5" boards, 0.125" gap)
Step 1: Calculate deck area: 20 × 12 = 240 sq ft
Step 2: Calculate effective width: 5.5 + 0.125 = 5.625 inches
Step 3: Calculate boards: (12 × 12) ÷ 5.625 = 144 ÷ 5.625 = 25.6 → 26 boards
Step 4: Add waste: 26 × 1.10 = 29 boards (with 10% waste)
Step 5: Calculate linear feet: 29 × 20 = 580 linear feet
Example 2: Larger Deck (30 ft × 16 ft, 7.25" boards, 0.125" gap)
Step 1: Calculate deck area: 30 × 16 = 480 sq ft
Step 2: Calculate effective width: 7.25 + 0.125 = 7.375 inches
Step 3: Calculate boards: (16 × 12) ÷ 7.375 = 192 ÷ 7.375 = 26 boards
Step 4: Add waste: 26 × 1.10 = 29 boards (with 10% waste)
Step 5: Calculate linear feet: 29 × 30 = 870 linear feet
About Decking Calculator
The Decking Calculator is an essential tool for homeowners, contractors, and DIY enthusiasts who need to accurately determine how many decking boards are required for their deck projects. This calculator eliminates guesswork by providing precise board counts based on deck dimensions, board width, and gap spacing, helping you order the right amount of materials without waste or shortages.
When to Use This Calculator
- Deck Construction: Calculate decking boards needed for new deck construction
- Deck Replacement: Determine materials for deck decking replacement projects
- Deck Repair: Estimate decking quantities for deck repair and renovation
- Budget Planning: Calculate material costs by determining exact board quantities needed
- Contractor Estimates: Quick reference for contractors bidding deck projects
Why Use Our Calculator?
- ✅ Accurate Board Count: Precise calculations prevent over-ordering or running short
- ✅ Linear Feet: Shows total linear feet needed for ordering
- ✅ Board Feet: Calculates board feet for pricing purposes
- ✅ Multiple Board Sizes: Supports different board widths (3.5", 5.5", 7.25", 9.25", 11.25")
- ✅ Gap Calculation: Accounts for gaps between boards for drainage and expansion
- ✅ Time Savings: Instant calculations eliminate manual math and measurements
Common Applications
Deck Construction: Homeowners and contractors planning deck construction use this calculator to order the correct quantity of decking boards. Standard decking uses 2×6 boards (5.5" width) with 1/8" gap, which this calculator helps determine accurately.
Deck Replacement: Contractors and homeowners planning deck decking replacement use this tool to estimate materials needed. Deck replacement typically uses similar dimensions to new construction but may require additional boards for repairs.
Budget Planning: Homeowners and contractors use this calculator to calculate decking quantities for budget planning and cost estimation, ensuring accurate project budgets.
Tips for Best Results
- Board Width: Standard is 5.5 inches (2×6); wider boards (7.25", 9.25") use fewer pieces but cost more
- Gap Spacing: Standard is 1/8 inch (0.125") for drainage; too small gaps trap water, too large looks unprofessional
- Add Waste: Always add 10% extra for waste, cuts, and mistakes
- Order by Linear Feet: Decking is typically sold by linear feet, not by board count
- Consider Board Length: Order boards that minimize waste based on deck dimensions
- Stagger Joints: Plan board layout to stagger end joints for better appearance and strength
Frequently Asked Questions
How many decking boards do I need for a 20×12 foot deck?
For a 20×12 foot deck using 5.5-inch boards with 1/8 inch gap, you'll need approximately 29 boards (with 10% waste). This equals about 580 linear feet of decking. Use the calculator with your specific dimensions for accurate count.
What size decking boards should I use?
Standard decking boards are 2×6 nominal (5.5 inches actual width). Wider boards (2×8, 2×10) use fewer pieces but cost more. Narrower boards (2×4) use more pieces but may look busy. Choose based on appearance preference and budget.
How much gap should I leave between deck boards?
Standard gap is 1/8 inch (0.125") between deck boards. This provides proper drainage and allows for wood expansion and contraction. Too small gaps trap water and cause damage. Too large gaps look unprofessional and can trap objects.
Do I need to add extra boards for waste?
Yes! Always add 10% extra for waste, cuts, and mistakes during installation. If you need 26 boards, order about 29 boards (with 10% waste) to ensure you have enough material.
Should I order by board count or linear feet?
Order decking by linear feet, not by board count. Decking is typically sold by linear foot, and the calculator shows linear feet needed. Multiply linear feet by price per foot to estimate costs.
What's the difference between decking and deck calculator?
The decking calculator focuses specifically on decking boards (the surface boards), while a deck calculator typically includes all deck materials (framing, decking, railings, etc.). Use the decking calculator for board calculations, and a comprehensive deck calculator for full project planning.