Home Systems Depreciation Calculator
Estimate the current depreciated (actual cash) value of major home systems using age, condition, and replacement cost. Useful for insurance claims, home sales, and budgeting.
Current cost to replace the system with a new equivalent.
Auto-filled by system type; you may override.
Condition applies an adjustment factor to the depreciated value.
Percentage of replacement cost retained at end of useful life (typically 0–15%).
Formula
Straight-Line Depreciation with Salvage Value & Condition Adjustment:
- Salvage Value = Replacement Cost × (Salvage %)
- Depreciable Base = Replacement Cost − Salvage Value
- Annual Depreciation = Depreciable Base ÷ Useful Life
- Accumulated Depreciation = Annual Depreciation × min(Age, Useful Life)
- Depreciated Value = Replacement Cost − Accumulated Depreciation
- Actual Cash Value (ACV) = max(Depreciated Value × Condition Factor, Salvage Value)
Condition Factors: Excellent = 1.10 | Good = 1.00 | Fair = 0.85 | Poor = 0.70
Assumptions & References
- Uses the straight-line depreciation method, the standard approach for insurance Actual Cash Value (ACV) calculations per ISO and the Appraisal Institute.
- Useful life estimates are based on the National Association of Home Builders (NAHB) Study of Life Expectancy of Home Components and the International Association of Certified Home Inspectors (InterNACHI) guidelines.
- Condition multipliers reflect adjustments used by property appraisers and insurance adjusters; they are approximations and may vary by insurer or jurisdiction.
- Salvage value (residual value) is typically 0–15% for most home systems; 10% is a common default.
- ACV is floored at the salvage value — a system cannot depreciate below its scrap/residual worth.
- This calculator does not account for inflation, regional cost variations, or functional obsolescence beyond age and condition.
- For insurance claims, always verify with your insurer's specific depreciation schedule, as policies vary.
- Results are estimates for informational and planning purposes only and do not constitute professional appraisal or insurance advice.