How to use the Irregular Shape Cubic Feet Calculator
- Break the shape into non-overlapping boxes, cylinders, cones or other supported solids. Label each row so the working can be checked.
- Add one row for each measured section. Choose its shape, quantity and whether to add solid volume or subtract a void.
- Select Calculate. Review the result and its working; if you change an input, calculate again before copying or sharing.
Irregular Shape formula
Calculate each section in cubic feet, multiply by its quantity and combine the positive and negative subtotals.
Net volume = Σ added volumes − Σ subtracted volumes
Irregular Shape worked examples
Start with one measured section
Represent a rectangular section as a 4 ft × 3 ft × 2 ft box and select Add solid volume.
- Section 1: L × W × H = 24 ft³ × 1 (add)
Answer: 24 ft³. Cubic yards: 0.888889 yd³; Litres: 679.604318 L.
Subtract a rectangular void
Start with a 4 ft × 3 ft × 2 ft solid, then subtract a 1 ft × 1 ft × 1 ft hole. The two sections do not overlap beyond the stated hole.
- Section 1: L × W × H = 24 ft³ × 1 (add)
- Section 2: L × W × H = 1 ft³ × 1 (subtract)
Answer: 23 ft³. Cubic yards: 0.851852 yd³; Litres: 651.287472 L.
Irregular Shape Cubic Feet Calculator FAQs
Can I subtract a hole?
Yes. Add the exterior components, then add a row set to subtract for the hole. Negative total volume is rejected.
Does this work from a photograph?
No. Each section needs measured dimensions. An arbitrary surface cannot be reconstructed from a photograph here.
Measurement guide for Irregular Shape
Sketch non-overlapping pieces before entering rows. Mark holes as subtraction rows and avoid counting a shared region twice.
Assumptions and limits
Avoid double counting overlaps. This method estimates a measurable solid; a single length, width and height only gives its bounding box.
Use non-overlapping sections. A bounding box can overestimate an irregular object.
Check your result
Review the subtotal of each section. The subtraction total must be smaller than the solid volume, and the measured sections must not double-count space.