How does an asset's value depreciate over its useful life?

Same asset, two schedules, one ending point

On this page’s defaults — a $50,000 asset, $5,000 salvage value, 5-year life — both methods write off the identical $45,000 total. They only disagree on the timing.

Straight-line divides the depreciable amount evenly: $45,000 ÷ 5 = $9,000 every year, no exceptions. Declining balance applies a fixed rate — here 2÷5 = 40%, the "double" in double-declining balance — to whatever book value remains, so the write-off shrinks every year: 40% of $50,000, then 40% of the $30,000 left, then 40% of $18,000, and so on.

Why year five breaks the pattern

Following the 40% rule mechanically in year five would depreciate $6,480 × 40% = $2,592 — but that would carry the book value below the $5,000 salvage floor, which accounting rules do not allow. The calculator catches this and caps the final year's depreciation at whatever is left: $6,480 − $5,000 = $1,480, landing exactly on salvage value rather than below it. Any declining-balance schedule needs this same check in its final year or two, once the shrinking write-off gets close to the floor.

What accelerated depreciation is actually for

Declining balance front-loads the same total deduction rather than creating a bigger one — $45,000 is written off either way. What changes is when the tax benefit lands: $20,000 in year one under declining balance against $9,000 under straight-line, more than double. For an asset that genuinely loses most of its usefulness early — a computer, a vehicle, most technology — this also tracks real economic value more honestly than a flat annual amount does. For a business managing taxable income, moving the deduction earlier is worth more today than the identical deduction spread evenly, because of the time value of money.

Straight-line vs. declining balance depreciation — what's the difference?

Straight-line depreciation spreads the exact same dollar amount evenly across every year of an asset's useful life — simple and predictable. Double-declining balance is an accelerated method that applies a fixed rate (double the straight-line rate) to the asset's shrinking book value each year, so it depreciates a much larger share early on and a smaller share later, tapering off but never dropping the book value below salvage value.

Why would a business choose accelerated depreciation?

Accelerated methods like double-declining balance produce larger depreciation deductions in the earlier years of an asset's life, which can improve near-term cash flow by lowering taxable income sooner rather than later. This is a general accounting note, not tax advice — consult a tax professional about which method actually applies to your specific asset and situation.

What is salvage value?

Salvage value, also called residual value, is the estimated worth of an asset at the end of its useful life — roughly what you could sell it for once it's been fully depreciated for accounting purposes. Total depreciation taken over an asset's life always equals its original cost minus this salvage value, regardless of which method spreads that amount out differently over time.

Does this apply to real estate?

Not directly — real property depreciation for US tax purposes uses IRS-mandated recovery periods, commonly 27.5 years for residential rental property and 39 years for commercial property, under specific methods set by tax law rather than a simple straight-line or declining-balance choice. This calculator is a general illustration of the underlying depreciation concept, not tax software, so don't use it for an actual real estate tax filing.

Worked example: a $50,000 asset with a $5,000 salvage value and a 5-year useful life depreciates $45,000 in total either way. Straight-line spreads that evenly at $9,000 a year. Double-declining balance (rate = 2 ÷ 5 = 40% of book value each year) depreciates $20,000 in year 1, $12,000 in year 2, $7,200 in year 3, $4,320 in year 4, and a final $1,480 in year 5 — capped so book value lands exactly at the $5,000 salvage floor rather than continuing below it.

A lease payment applies this same straight-line logic every month instead of every year — the Lease Calculator spreads an asset's value minus its residual evenly across the lease term, the identical arithmetic as straight-line depreciation paid out on a shorter cycle.