How to use this calculator
- Measure the project and enter the requested dimensions. Use actual product dimensions where the form asks for them.
- Replace the sample assumptions with the spacing, stock lengths, coverage, or prices that apply to your plan.
- Review the result, assumptions, and any limitation notice. Save the project locally or export a dated PDF for discussion.
Calculation methodology
Rectangles use length × width; L-shapes subtract the corner cutout; multi-section plans use exact axis-aligned rectangle union area so overlaps count once; polygons use the shoelace formula.
Intermediate values retain decimal precision. Physical purchase units are rounded up only at the purchasing step, so the tool does not silently understate whole boards, bags, boxes, or containers.
Worked example
A 16 × 12 ft deck with a 4 × 4 ft corner removed has 176 sq ft of plan area.
Material and measurement considerations
- Measure consistent reference edges.
- Overhangs can make decking area differ from framing area.
- Curves require a more detailed survey.
Common mistakes
- Adding overlapping rectangles twice.
- Mixing inches with feet.
- Listing polygon points out of boundary order.
Frequently asked questions
Can sections overlap?
Yes. The two-section mode calculates their union so the shared area is counted once.
Sources and limitations
The estimator uses your measurements, standard geometry, unit conversion, and product data you enter. Product coverage, gaps, fastening, and installation details should come from the current manufacturer documentation for the exact material. Structural and permit requirements must be confirmed for the project location. No live price feed, fabricated standard, or universal structural rule is used.