Blast Perimeter Calculator
Computes the perimeter of a blast footprint from a rectangle or polygon corners, with an edge table and area — a boundary length, not an exclusion zone.
Inputs
Perimeter of a blast footprint from a rectangle or polygon vertices, with an edge table and area — a boundary length, not an exclusion zone.
Enter the values and press Calculate.
Or load an example to see a worked result.
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Choose a rectangle (length and width) or a polygon (corner coordinates in order).
- For a polygon, enter E, N — or label, E, N — one corner per line in one projected unit. The last corner joins back to the first automatically.
- Read the perimeter, the edge table and, for a boundary that does not cross itself, the footprint area.
How it works
Rectangle: P = 2 × (L + W). Polygon: P = Σ √((E₂ − E₁)² + (N₂ − N₁)²) over every edge, including the closing edge back to the first corner.
A final corner that repeats the first is not counted twice. Area = |shoelace sum| ÷ 2, given only when the boundary does not cross itself; a self-intersecting boundary is flagged and no area is claimed.
This is the blast footprint boundary length. It is not an exclusion zone, clearance radius or stand-off distance, and none is derived from it.
Worked example
40 m × 25 m block. P = 2 × (40 + 25) = 130 m. A square with corners (0, 0), (10, 0), (10, 10), (0, 10) has a perimeter of 40 m and an area of 100 m²; repeating (0, 0) at the end changes nothing.
Frequently asked questions
Perimeter or exclusion zone?
Perimeter only. An exclusion or clearance zone comes from your approved blast management plan and site rules, not from the footprint length.
Can I enter irregular boundaries?
Yes — choose Polygon and list the corners in order around the block. The edge table shows each side, so you can check the order.
Which coordinate units?
Projected grid coordinates (easting, northing) in metres or feet, all in one unit. Latitude and longitude are angles and must be projected first.
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Cite this tool
Zerdly. (2026). Blast Perimeter Calculator. Retrieved from https://www.zerdly.com/tools/blast-perimeter-calculator/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.