Slab Load Calculator

Self weight (intensity):

• w_self = ρ × t
• Metric: ρ in kN/m³, t in m, result in kN/m².
• Imperial: ρ in pcf, t in ft, result in psf.

Component loads:

• D = (include w_self) + (include finishes + partitions)
• L = (include live load)
• Service = D + L

Factored design load (choose one):

• U = 1.5D + 1.5L
• U = 1.2D + 1.6L
• U = 1.35D + 1.5L

1. Select a unit system and your design load combination.
2. Enter slab length, width, and thickness.
3. Set concrete density and add finishes/partitions as needed.
4. Enter the live load from the occupancy category.
5. Choose which components to include, then press Calculate.
6. Review service and factored totals, then export CSV or PDF.

Values are illustrative. Always follow your local code requirements.

1) Why slab load calculations matter

Slabs transfer gravity actions to beams, columns, and walls. A clear load estimate supports safe sizing, sensible reinforcement, and reliable foundations. This calculator summarizes dead and live loads as intensities and totals, then applies a factored combination for design checking.

2) Geometry inputs and load intensity

Uniform slab load is commonly expressed per unit area. Area equals length multiplied by width, while thickness converts into volume per square meter or square foot. With geometry set, the calculator converts material density and thickness into self weight intensity, a primary component of dead load.

3) Concrete density and typical values

Normal-weight reinforced concrete is often taken near 24 kN/m³ in metric units, or about 150 pcf in imperial units. Lightweight mixes can be lower, and heavy concrete higher. Use project specifications when available, because self weight scales directly with density and thickness.

4) Superimposed dead loads from finishes

Floor finishes, screed, tiles, waterproofing layers, and ceiling services add permanent load beyond the slab. For preliminary work, finishes may range around 0.5–1.5 kN/m² depending on build-up. Input these as finishes and partitions so the dead load reflects real usage.

5) Partition allowances and fit-out uncertainty

Movable or future partitions are often treated as an equivalent uniformly distributed load. Offices and commercial areas may use higher allowances than residential spaces. If layouts are not finalized, choose conservative values. This calculator lets you toggle partitions separately so you can compare scenarios.

6) Live load selection and occupancy data

Live load depends on how the space is used: residential rooms commonly sit near 2.0 kN/m², offices can be higher, and storage areas can increase significantly. Always reference the governing building code for the category. The calculator applies live load only when enabled.

7) Service versus factored demand

Service load is the unfactored sum of dead and live components and is useful for deflection checks and load summaries. Factored demand applies safety factors to represent worst credible combinations used for strength design. Select the combination that matches your code or office standard.

8) Reading outputs and practical quality checks

Review the intensity table first: self weight, superimposed dead, and live load should look reasonable. Then confirm totals by multiplying intensity by area. If results appear off, recheck units, thickness conversion, and whether a component was excluded. Export CSV or PDF for records.

1) What does “slab load” mean here?

It is the uniform gravity load on a slab per unit area and as a total. The calculator combines self weight, superimposed dead loads, and live load into service and factored results.

2) Does this include beam or wall loads?

No. It evaluates slab area loads only. Line loads from walls, beams, or façade elements should be converted separately and applied to the supporting members using appropriate tributary widths.

3) How is self weight calculated?

Self weight intensity equals material density multiplied by slab thickness. Use kN/m³ and meters for metric, or pcf and feet for imperial. The result is kN/m² or psf respectively.

4) What should I enter for finishes and partitions?

Use realistic project allowances. Finishes often fall around 0.5–1.5 kN/m², while partition allowances vary by occupancy. If uncertain, start conservative and compare cases by toggling components.

5) Which factored combination should I choose?

Select the combination used by your design code or office practice. The tool offers common forms so you can quickly see how factors change the demand relative to the service load.

6) Can I use this for point loads or machinery loads?

Not directly. Convert concentrated actions into equivalent distributed loads or design the slab locally with appropriate methods. For heavy equipment, consult detailed design guidance and manufacturer data.

7) Are the exports suitable for submission?

They are helpful for documentation and internal checks. For formal submission, include code references, assumptions, and engineer review. Treat the export as a calculation note, not a sealed design.

Notes

• This tool evaluates uniform area loads only, not point loads.
• For long spans, check deflection and vibration separately.
• Use conservative allowances when finishes are uncertain.