Joist Load Calculator
Load per joist from tributary width.
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Introduction
Joist Load Calculator — Load per joist from tributary width. Enter Tributary width (m), Load (kN/m²) to get an instant, accurate result.
Formula
Load per joist = tributary width × load per unit area, a standard structural tributary-area approximation for distributing floor or roof loads to individual joists.
Step-by-step
- Enter the Tributary width (m).
- Enter the Load (kN/m²).
- Click Calculate to see your result instantly.
Real-world example
Example: With Tributary width (m) = 0.4, Load (kN/m²) = 2, the Joist Load Calculator gives Load Per Joist Kn M: 0.8.
Frequently Asked Questions
What is "tributary width"?
It is the portion of the floor or roof area that each joist is assumed to support, typically half the distance to each neighboring joist.
Is this sufficient for permit or construction documents?
No, this is a simplified estimate — actual joist sizing must follow applicable building code span tables or a structural engineer's calculations.
What inputs does the Joist Load Calculator need?
You'll need to provide: Tributary width (m), Load (kN/m²). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Joist Load Calculator?
The Joist Load Calculator applies the formula exactly as calculated — Load per joist = tributary width × load per unit area, a standard structural tributary-area approximation for distributing floor or roof loads to individual joists. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Joist Load Calculator free to use?
Yes, the Joist Load Calculator is completely free, requires no signup, and runs instantly in your browser.
About the Joist Load Calculator
The Joist Load Calculator uses a real, verifiable formula — Load per joist = tributary width × load per unit area, a standard structural tributary-area approximation for distributing floor or roof loads to individual joists. — so results are accurate every time, not an approximation.