How to Use the Concrete Floor Load Capacity Calculator

Input the Dimensions and Material Properties:

1. Concrete Strength (f’c):
   • Enter the compressive strength of the concrete in pounds per square inch (psi).
   • Example: 4000 psi
2. Slab Thickness (t):
   • Enter the thickness of the concrete slab in inches.
   • Example: 6 inches
3. Span Length (L):
   • Enter the length of the span in feet.
   • Example: 10 feet
4. Safety Factor:
   • Enter the safety factor. The default value is 1.75.
   • Example: 1.75

Click the Calculate Button:

• After entering all the required values, click the “Calculate Load Capacity” button to perform the calculations.

View the Results:

• Moment of Inertia (I): This is the moment of inertia of the slab in in⁴.
• Section Modulus (S): This is the section modulus of the slab in in³.
• Moment Capacity (M): This is the moment capacity in in-lb.
• Load Capacity (P): This is the load-carrying capacity of the slab in pounds per square foot (psf).

Example Calculation

• Concrete Strength (f’c): 4000 psi
• Slab Thickness (t): 6 inches
• Span Length (L): 10 feet
• Safety Factor: 1.75

Step-by-Step Calculation:

Convert span length to inches:

• L = 10 feet × 12 = 120 inches

Calculate the Moment of Inertia (I):

• I = t³/12
• I = 6³/12
• I = 18 in⁴

Calculate the Section Modulus (S):

• S = 𝑡²/6
• S = 6²/6
• S = 6 in³

Calculate the Moment Capacity (M):

• M = (𝑓′𝑐 x S )/ Safety Factor 
• M = (4000 × 6) / 1.75
• M = 13714.29 in-lb

Calculate the Load Capacity (P):

• P = ( 8 x M ) /  L²
• P = ( 8 x 13714.29 ) / 120²
• P = 7.62 lb/in²

Convert to pounds per square foot (psf):

• P = 7.62  lb/in² × 144
• P = 1097.28 psf

Result: