Accumulated Depreciation Calculator

Accumulated depreciation is the running total of depreciation recorded against an asset. This calculator estimates that running total and the remaining book value using the method selected in the form. It supports straight-line, declining balance, sum-of-years’ digits, and units of production. It also reports depreciable base, depreciated share of cost, method used, and the period measured.

Use this page when you already know an asset’s cost, salvage value, and either years in service or units produced so far. If you need a full year-by-year schedule, use the depreciation calculator. For assets whose market value falls in a vehicle-specific pattern, the car depreciation calculator is more appropriate. For household property estimates, compare the appliance depreciation calculator.

Inputs and validation

The calculator requires asset cost and salvage value for every method. Salvage value cannot be greater than cost. The depreciable base is cost minus salvage value. For time-based methods, enter useful life and years in service. Years in service is capped at useful life inside the calculation, so a 12-year input on a 10-year life is treated as 10 years. For declining balance, enter a rate from 0% to 100%. For units of production, enter estimated lifetime units and units produced so far; units produced is capped at lifetime units for the depreciation calculation.

The result is accumulated depreciation after caps are applied. The calculator then subtracts that amount from cost to get book value. It also divides accumulated depreciation by cost to show the depreciated share of original cost.

Formulas by method

Straight-line spreads the depreciable base evenly:

$\text{accumulated depreciation} = \frac{\text{cost} - \text{salvage value}}{\text{useful life}} \times \text{capped years}$

Declining balance uses the original cost and compounds the remaining percentage:

$\text{accumulated depreciation} = \text{cost} \times \left(1 - (1 - \text{rate})^{\text{capped years}}\right)$

Sum-of-years’ digits uses an accelerated fraction. The calculator’s numerator for the years used is:

$\text{numerator} = \frac{\text{capped years} \times (2 \times \text{useful life} - \text{capped years} + 1)}{2}$

The denominator is:

$\text{denominator} = \frac{\text{useful life} \times (\text{useful life} + 1)}{2}$

Units of production uses actual output:

$\text{accumulated depreciation} = (\text{cost} - \text{salvage value}) \times \frac{\text{capped units produced}}{\text{estimated lifetime units}}$

Every method is finally limited to the depreciable base:

$\text{book value} = \text{cost} - \text{accumulated depreciation}$

Example

Use the default straight-line inputs: asset cost 700,000, salvage value 280,000, useful life 40 years, and years in service 5. The depreciable base is 700,000 minus 280,000, or 420,000. Straight-line annual depreciation is 420,000 divided by 40, or 10,500. Accumulated depreciation after 5 years is 10,500 · 5, or 52,500. Current book value is 700,000 minus 52,500, or 647,500. The depreciated share of cost is 52,500 divided by 700,000, multiplied by 100, or 7.50%.

For a units-of-production example, use cost 90,000, salvage 10,000, estimated lifetime units 100,000, and units produced so far 30,000. The base is 80,000. The production fraction is 30,000 divided by 100,000, or 0.30. Accumulated depreciation is 80,000 · 0.30, or 24,000, and book value is 66,000. If units produced were entered as 125,000, the calculator would cap units at 100,000 and accumulated depreciation at the 80,000 base.

When accumulated depreciation is used

Accumulated depreciation appears on the balance sheet as a contra-asset account. It lets the original cost remain visible while reducing carrying value for the portion already expensed. Accountants use it when preparing financial statements, reviewing fixed-asset registers, planning disposals, and reconciling equipment schedules. Managers use it to see how much book value remains before repair, replacement, or sale decisions.

The method matters. Straight-line is easy to explain and often fits assets that provide even service. Declining balance and sum-of-years’ digits recognize more depreciation early. Units of production fits machinery, tools, or equipment where usage is a better driver than time. The best method is usually the one already set by accounting policy, lender reporting, or tax rules.

Tips and cautions

• Separate land from buildings because land is normally not depreciated.
• Use the same cost basis in every period so the running total reconciles.
• Do not treat accumulated depreciation as a savings account for replacement.
• Review salvage estimates when market conditions change materially.
• For tax depreciation, check IRS Publication 946 rather than assuming this book estimate matches a return.

A useful review habit is to compare the calculator’s book value with the fixed-asset register after every close. If the register shows a different remaining value, look for partial disposals, capital improvements, revised salvage estimates, or a method change. The calculator is intentionally transparent, so differences are easier to trace than they would be in a black-box accounting export.

Displayed results use the currency, time period, percentage, or other units named in the tool and round only for presentation; retain additional precision when carrying a result into another calculation.

Sources

• IRS, Publication 946: How to Depreciate Property — tax depreciation rules and property context.
• CFI, Depreciation Methods — straight-line and accelerated method overview.
• AccountingTools, What is accumulated depreciation? — accumulated depreciation definition and accounting treatment.
• AccountingTools, Depreciation — depreciation concept and accounting context.