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Background Calculator — Backdrop Panels & Print Size

Size backdrop panels and calculate print dimensions for your diorama background.

Add overlap at joins

Adds 20mm where panels meet for gluing (one join on L, two on U). A single flat panel has no join, so nothing is added.

How We Calculate This

The calculator sizes your backdrop based on the base dimensions and your chosen shape (flat, L, U or curved).

Layout Calculations

  • Flat: Width = base length (single panel, no join so no overlap)
  • L-shape: Width = base length + base width + overlap
  • U-shape: Width = base length + (2 x base width) + overlaps
  • Curved: Width = depth ratio × approximate full perimeter of the base ellipse (default 0.75), where the perimeter is approximated as π × (length + width) ÷ 2

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.