Live Load Calculator

Work out live load instantly with clear inputs, formula shown and shareable results.

About Live Load Calculator

Live load intensity comes from the occupancy schedule: about 2 kPa for residential, 3 for offices, 4 for retail and 5 for assembly. Where a member supports a large influence area, codes permit a reduction because full loading everywhere at once is improbable, using a factor of 0.25 + 4.57 / sqrt(influence area) with a floor of 0.4.

Formulas

Reduction factor

R = 0.25 + 4.57 / sqrt(influence area m²), not less than 0.40

Reduced load

Reduced kPa = tabulated live load x R

Worked example

With the default values below, Live Load Calculator returns Reduced live load of 1.473. Change any input above and every figure here is recalculated in your browser.

Inputs used

Occupancy typeone of Residential — 2.0 kPa, Office — 3.0 kPa, Retail — 4.0 kPa, Assembly — 5.0 kPa: Office — 3.0 kPa
Tributary areaminimum 0.1 m²: 120 m²
Floors supportedminimum 1: 3

Results

Reduced live load: 1.473 kPa
Unreduced live load: 3.00 kPa
Reduction factor: 0.4909
Total reduced live load: 530.1 kN

Step by step

1Values used
2Reduction factor
3Reduced load
4Reduced live load= 1.473 kPa
5Unreduced live load= 3.00 kPa
6Reduction factor= 0.4909
7Total reduced live load= 530.1 kN

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Live load values and permissible reductions must be taken from the loading code adopted locally.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Live load values and permissible reductions must be taken from the loading code adopted locally.

Frequently Asked Questions

How is the Live Load figure worked out?

R = 0.25 + 4.57 / sqrt(influence area m²), not less than 0.40. Live load intensity comes from the occupancy schedule: about 2 kPa for residential, 3 for offices, 4 for retail and 5 for assembly.

Does the reduction apply to slabs?

No. It applies to beams, columns and foundations with large influence areas. The slab itself must carry the full tabulated intensity locally.

What values do I need to enter?

This calculator takes 3 inputs: Occupancy type, Tributary area, Floors supported. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.