UK cost calculator
Loft Conversion Cost Calculator
Compare Velux, dormer, hip-to-gable, mansard, shell-only and bungalow conversion budgets using current 2026 UK benchmarks.
Estimated project range
£37,600 – £56,400Typical planning estimate £47,000. Benchmarked to 2026 UK loft-conversion ranges; size scaling and regional adjustment are UK Home Costs modelling assumptions.
Benchmark source: Checkatrade 2026 loft conversion cost guide, last updated March 2026. Regional, floor-area and ensuite adjustments are UK Home Costs modelling assumptions. See sources →
How the loft estimate works
The calculator starts with a published benchmark for the selected conversion type, then scales the reference area and applies a regional factor. An ensuite is added separately so the source benchmark is not confused with our modelling assumptions.