Depreciation calculator: compute straight line, declining balance, and sum of years digits depreciation schedules by asset. Free, runs in your browser.
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Every figure above is calculated locally in your browser from the assumptions shown. No inputs are sent anywhere. See the methodology section below for the formulas used.
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Depreciation calculator: compute straight line, declining balance, and sum of years digits depreciation schedules by asset. Free, runs in your browser.
Straight line spreads $35,000 into $7,000 per year.
Transparent methodology
How this calculator works
Reviewed August 2026 · BoringToolsKit Editorial Team
Formula
Straight-line: annual = (cost - salvage) / useful years; book value declines by that amount each year.
Worked example
A $50,000 asset with $5,000 salvage over 5 years: $9,000 of depreciation a year, ending at $5,000 book value.
BoringToolsKit. “Depreciation Calculator.” boringtoolskit.com/depreciation-calculator/ (reviewed August 2026). Free to reference in articles, syllabi, and answer posts with a link.
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Worked example: $40,000 machine over 5 years
Suppose a machine costs $40,000, has a salvage value of $5,000, and a 5-year life. The depreciable base is $40,000 minus $5,000, or $35,000. Straight line divides that base by the life: $35,000 / 5 = $7,000 per year. The book value falls $7,000 each year, from $40,000 to $33,000 after year one, $26,000 after year two, and $5,000 after year five, which equals the salvage value exactly.
Switch the method to double declining balance and the same inputs behave differently. The rate is 2 / 5 = 40% of remaining book value. Year one takes 40% of $40,000, or $16,000, leaving $24,000. Year two takes $9,600, leaving $14,400; year three takes $5,760, leaving $8,640. A full schedule must stop at the $5,000 salvage floor, so later years shrink: roughly $3,456, then a final $1,184 write-off. The calculator reports the first-year figure of $16,000, which is why the straight line number ($7,000) and the declining balance number ($16,000) differ by more than double despite the same rate multiplier.
Limits of a first-year-only answer
This tool reports one annual figure, not a full schedule. Declining balance is inherently front-loaded: the second year is 40% of what remains, not another $16,000. If you need year-by-year book values for a balance sheet, extend the pattern yourself or use accounting software, because a real DDB schedule also clamps the final year so book value never drops below salvage. The snippet above computes the first-year book value only and does not apply that clamp across later years.
Two conventions are also missing. First, tax depreciation rarely matches book depreciation: US MACRS uses half-year conventions and fixed percentage tables, so a 5-year MACRS asset deducts 20%, 32%, 19.2%, and so on, not 40% of declining value. Second, partial-year purchases: an asset placed in service in July typically gets a half year of straight line expense ($3,500 in the example above), which this annual figure does not reflect. Treat results as planning estimates for book depreciation, not a substitute for a tax preparer's schedule.
