How this calculator works
Straight-line depreciation spreads an asset’s depreciable cost evenly across its useful life. Book value falls by the same amount each year until it reaches the residual value. Fractional ages prorate the annual amount.
Annual depreciation = (cost − residual value) / useful lifeP = starting amount; C = monthly contribution; G = target; r = monthly rate; n = months; y = years, where applicable.
Example you can check
An asset costing $10,000 with a $1,000 residual value and five-year useful life depreciates $1,800 per year. After two years, book value is $6,400.
Assumptions & limitations
No accelerated depreciation, impairment or partial-year accounting conventions. Book value is not market value. This is a planning illustration, not a jurisdiction-specific tax calculation.
Common questions
Is this the price I can sell the asset for?
No. Market value depends on demand, condition and comparable sales.
What happens after the useful life?
The estimated book value stays at the residual value; it does not fall below it.
Further reading: irs.gov educational guide. Our formula conventions and examples are described above.