Deck Joist Calculator
Formula: Joists = ⌈ Width / spacing ⌉ + 1
Frequently asked questions
How accurate is the Deck Joist Calculator?
Results are estimates suitable for planning, budgeting and material ordering. Field conditions, local codes and product specifications may require adjustments — always verify with a licensed professional before purchasing or building.
Does it support both metric and imperial units?
Yes. Use the unit switcher at the top of the calculator to toggle between metric (meters, kilograms, liters) and imperial (feet, inches, pounds, gallons).
Should I add a waste factor?
For most construction materials, add 5-15% waste depending on cut complexity. Tile and flooring often need 10%, while bulk materials like concrete and mulch need 5-10%.
Can I save or print my results?
Yes — use the Print, Copy and Share buttons on the result card to send estimates to your phone, email or contractor.