Strip foundation calculator
Concrete volume for a strip from its length, width and depth.
Fill in the fields and the result will appear here automatically.
Calculates concrete in a strip of constant rectangular section. Use the length of all planned portions rather than automatically entering the building perimeter. Correct intersections so the same volume is not counted twice. Net volume and added reserve are shown separately; depth and width come from the design, not from calculator selection.
How it works
Formula and logic
Constant rectangular section: net volume V = L·b·h, section area b·h, with reserve Vₛ = V(1 + w/100), 0 ≤ w ≤ 50%. L is the equivalent length of non-overlapping portions with the same section. Simply summing intersecting strip centrelines can count junctions twice; intersections are not automatically deducted. Dimensions are positive and finite. Depth selection, soil, loads, rebar and formwork are outside this model.
Example
A 40 m strip with a 0.4 × 0.8 m section is 12.8 m³ of concrete; with a 5 % allowance you order 13.44 m³.
Fields and units
- Total strip length — m
- Strip width — m
- Strip depth — m
- Allowance — %
How to use
- — Determine equivalent length of non-overlapping portions of the same section.
- — Enter width and height of the concrete strip itself in m.
- — Choose your reserve from 0 to 50%; check intersections against the plan.
Method and limitations
- Calculation method
- Formula and logic
- Limitation
- This is a geometric quantity calculation within the described model. It does not establish load capacity, safety or project compliance; check design parameters separately.
FAQ
Do I enter the strip length or the building perimeter?
Use the equivalent length of all non-overlapping portions of the same section. Internal strips add volume, but simply summing centrelines can count intersections twice. Correct junctions from the plan; the outer perimeter alone does not describe every strip network.
How is this different from the concrete calculator?
The concrete calculator covers three pour shapes in general. This one covers only the strip, but from the quantity it is actually measured by, and with labels that stop the strip length being confused with the size of the house.
How do I allow for the sand bed?
You do not — it is not concrete. Work its volume out separately from the same strip length and the bedding thickness.
Should reinforcement be subtracted?
Rebar volume is not deducted here: the result is the external geometric volume of the concrete section. This is a stated model assumption, not a claim that steel is always negligible. Count displaced volume separately if your accounting requires it.