Attic Conversion Cost Calculator
Last updated: October 15, 2026
Estimate an attic conversion budget including finished area, stairs, insulation, HVAC, permits and contingency.
Starting figures illustrate this model. Enter your own measurements, quoted costs and applicable terms; this page does not retrieve live prices or provider rates.
Estimated attic-conversion cost
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- Base conversion estimate: —
- Stairs, systems and permits: —
- Estimated contingency: —
- Estimated cost per finished square foot: —
On this page
Quick summary: Estimate an attic conversion budget including finished area, stairs, insulation, HVAC, permits and contingency.
Read the complete guide
Updated reference sections in this guide are in English.
What this calculator estimates
Estimate an attic conversion budget including finished area, stairs, insulation, HVAC, permits and contingency.
How to use it
Enter Finished attic area (square feet); Base conversion cost per square foot ($); Stair and access work ($); HVAC, insulation and electrical work ($); Design, permits and inspections ($); Contingency (%). Select Calculate to update the results.
How the calculation works
The base finished-area estimate is combined with stairs, building systems, permits and a contingency allowance.
Worked example: starting scenario
| Finished attic area (square feet) | 750 |
|---|---|
| Base conversion cost per square foot ($) | 110 |
| Stair and access work ($) | 12000 |
| HVAC, insulation and electrical work ($) | 18000 |
| Design, permits and inspections ($) | 7500 |
| Contingency (%) | 12 |
| Estimated attic-conversion cost | $134,400.00 |
|---|---|
| Base conversion estimate | $82,500.00 |
| Stairs, systems and permits | $37,500.00 |
| Estimated contingency | $14,400.00 |
| Estimated cost per finished square foot | $179.20 |
Important limitations
Headroom, structure, egress, fire code, roofing, plumbing, dormers, location and finish level can materially change the cost.