Concrete slab calculator
Estimate the geometric and allowance-adjusted concrete volume for one rectangular slab.
How to use this calculator
How to measure
Measure the inside form length and width and the designed uniform thickness. Confirm structural thickness and reinforcement with the project documentation.
Worked example
A 5 m × 4 m slab, 0.1 m thick, has 2 m³ geometric volume. A 10% order allowance gives 2.2 m³.
Formula and purchasing method
slab volume = length × width × thickness; order volume = slab volume × (1 + allowance/100).
Assumptions
- The slab has constant thickness and rectangular plan.
- The user selects the order allowance explicitly.
Limitations
- This is quantity estimation, not structural design.
- Footings, thickened edges, reinforcement, pumping loss and supplier minimums are excluded.
FAQ
Does this choose slab thickness?
No. Thickness is a design input and must come from the approved project.
Why is the result not rounded to trucks?
Ready-mix increments and minimum orders vary by supplier; order volume remains continuous.
Sources
Product-specific values must be copied from the exact current label or technical datasheet; linked examples document the method and its limits.
Calculation privacy
Calculations run locally. Form inputs and results stay in your browser.
How storage works and how to delete data