Diminishing Value Depreciation Calculator
Straight-line depreciation spreads an asset’s cost evenly, but most assets lose value fastest in their first years. The diminishing value method, also called declining balance, captures that pattern: each year it applies a fixed percentage to the book value that is left, so the expense starts large and shrinks as the balance shrinks.
This calculator shows the full year-by-year schedule, depreciation, accumulated depreciation, and book value for every year, and it has a second mode that runs diminishing value against prime cost (straight-line) side by side, so you can see exactly how much the method choice moves the early years.
Full years only. This schedule works in whole years and does not prorate a partial first year by days held, which some tax systems, including Australia’s diminishing value formula, require. See the tax note below.
Quick Answer
Key takeaways
- Diminishing value applies one fixed rate to a shrinking balance, so the dollar expense falls every year: $2,000, then $1,600, then $1,280 on the worked example.
- The book value is floored at salvage value. The schedule trims the final year's depreciation so the value lands exactly on salvage and never below it.
- The standard accelerated rate is 200% divided by the effective life: 40% for a 5 year life. The comparison tab uses that rate automatically.
- Method choice is about timing, not totals. Diminishing value front-loads the deduction; prime cost spreads the same depreciable amount evenly.
- Quick Answer
- How the schedule builds, year by year
- The diminishing value formula
- Worked example: $10,000 at 20% for 3 years
- Diminishing value vs prime cost on the same asset
- The tax note: full years here, days held in real tax formulas
- What competing calculators miss
- Frequently Asked Questions
- Add This Calculator to Your Website
- References
How the schedule builds, year by year
Each year repeats the same three moves on a smaller balance, which is the whole method.
Take the opening book value. Year 1 opens at the full cost, $10,000 in the example. Every later year opens at whatever the previous year closed at.
Apply the rate to that opening value. At 20%: year 1 depreciation is $10,000 x 20% = $2,000. Year 2 is $8,000 x 20% = $1,600, because the base shrank.
Subtract, check the floor, repeat. Closing book value is opening value minus depreciation. If that would fall below salvage value, the depreciation is trimmed so it lands exactly on salvage, and the schedule stops there.
That loop is also why the closed-form shortcut works: book value after n years equals cost x (1 minus rate)n, before the salvage floor is applied. For the example, $10,000 x 0.83 = $5,120, matching the schedule row for year 3 exactly. Assets whose value is consumed by use rather than time follow a different logic altogether; wearing out a reserve or a mine, for instance, is tracked with the asset depletion calculator, not a time-based percentage.
The diminishing value formula
One multiplication per year, applied to a moving base.
The rate is where judgment enters. A rate of 200% / life, called double declining in United States practice and the standard diminishing value rate under the Australian Taxation Office's prime cost and diminishing value methods, ties the rate to the asset's effective life: a 5 year life gives 40%, a 4 year life gives 50%, and both are one click on the preset buttons. A rate of 100% / life applies the straight-line percentage to the balance instead of the cost base, which produces a gentler decline. This calculator lets you type any rate, because software, vehicles, and plant all wear at different speeds, and presets should be a starting point, not a cage.
Salvage value works differently here than in straight-line. In prime cost, salvage shrinks the amount to be spread. In diminishing value, salvage is only a floor: the rate is applied to the full opening balance, and salvage matters only in the year the balance would otherwise cross it. That is why the same $10,000 asset with a $1,000 salvage value follows the identical schedule until the closing year, then trims the last charge to land on $1,000.
Worked example: $10,000 at 20% for 3 years
The schedule tab is pre-filled with this case: cost $10,000, useful life 5 years, salvage $0, rate 20%, years elapsed 3.
| Year | Depreciation | Accumulated depreciation | Book value |
|---|---|---|---|
| 1 | $2,000.00 | $2,000.00 | $8,000.00 |
| 2 | $1,600.00 | $3,600.00 | $6,400.00 |
| 3 | $1,280.00 | $4,880.00 | $5,120.00 |
The bars show the shape that gives the method its name: the balance falls by a fifth of itself each year, so the steps get smaller in dollar terms even though the percentage never changes. Compare that with a vehicle valued for sale rather than for the books, where market guides drive the number; the BMW depreciation calculator follows that market-value path for one marque. When this asset is eventually sold, the $5,120 book value at year 3 is the figure the gain or loss is measured against, which is the territory of the asset adjusted basis calculator.
Diminishing value vs prime cost on the same asset
The comparison tab removes the rate question by fixing it at 200% / life, 40% for this asset's 5 year life, and running prime cost alongside.
| Year | DV depreciation | DV book value | Prime cost depreciation |
|---|---|---|---|
| 1 | $4,000.00 | $6,000.00 | $2,000.00 |
| 2 | $2,400.00 | $3,600.00 | $2,000.00 |
| 3 | $1,440.00 | $2,160.00 | $2,000.00 |
| 4 | $864.00 | $1,296.00 | $2,000.00 |
| 5 | $518.40 | $777.60 | $2,000.00 |
Read the last row honestly. After 5 years prime cost has expensed the full $10,000, while diminishing value has expensed $9,222.40 and leaves a $777.60 book value above the zero salvage floor, because a percentage of a balance never quite reaches zero in a finite number of years. In practice that tail is handled by the salvage floor when salvage is above zero, by switching to prime cost in the later years, or by writing the asset off on disposal. If the even pattern is the one you actually need for the books, the depreciation expense calculator gives the single annual straight-line figure directly.
Which method wins depends on the business's profit pattern. Front-loading suits a business with strong early profits from the asset, because the bigger deduction lands where it shelters the most tax. Even deductions suit a business that wants stable reported costs. The totals converge; the timing, and the tax year each dollar lands in, is the decision.
The tax note: full years here, days held in real tax formulas
This schedule works in whole years, with no partial-year proration. Real tax formulas often do prorate. The Australian diminishing value formula, for example, multiplies the base value by days held / 365 as well as by 200% / effective life, so an asset bought halfway through the year claims roughly half the first-year amount this schedule shows.
United States tax law takes yet another route: MACRS declining balance classes switch to straight-line partway through the recovery period and use half-year or mid-quarter conventions, all set out in IRS Publication 946, How to Depreciate Property. Use this calculator to understand the pattern, compare methods, and plan; use your jurisdiction's exact formula, or your accountant, for the claim itself.
Disclaimer: this calculator is an educational tool showing the diminishing value pattern in full years. It is not tax advice, and it does not apply days-held proration, MACRS conventions, or instant write-off thresholds.
What competing calculators miss
The rival tools for this term tend to return a single ending value, and that hides almost everything that matters about this method.
Miss 1: one number instead of the schedule. A final book value does not tell you what to book in year 2. This tool prints every year: depreciation, accumulated depreciation, and book value, for the number of years you choose.
Miss 2: no salvage concept. Tools that apply a percentage until the balance fades ignore the floor that real accounting applies. Here the schedule trims the final charge and stops exactly on salvage value, and the result line tells you how much value sits above salvage.
Miss 3: no method comparison. The decision people actually face is diminishing value or prime cost. The comparison tab runs both on the same inputs at the standard 200% / life rate and shows the year 1 gap in dollars, $2,000.00 on the worked asset, instead of describing front-loading in the abstract.
One gap this page shares with most rivals, stated openly: large multi-method suites also offer sum-of-the-years-digits and units of production. This page does not, because its job is the diminishing pattern and the prime cost comparison done properly.
Frequently Asked Questions
A depreciation method that applies a fixed percentage rate to the asset's remaining book value each year, so depreciation is largest in year 1 and shrinks over time. It is also called the declining balance method.
Prime cost deducts the same amount every year: (cost minus salvage) / life. Diminishing value deducts a percentage of the shrinking balance, front-loading the deduction. The total depreciated over the asset's life is the same; the timing differs.
A common accelerated rate, used in Australian tax rules: twice the straight-line rate. For a 5-year life the diminishing rate is 40%. The calculator's presets include these standard rates.
No. The calculator floors the book value at salvage: the final year's depreciation is trimmed so the value lands exactly on salvage and stays there.
Diminishing value, because it front-loads deductions. Businesses expecting higher early profits often prefer it; businesses wanting smooth deductions prefer prime cost.
Mathematically the book value approaches but never reaches zero, which is why a salvage value (or a switch to prime cost in later years) matters in practice.
Because a percentage of a shrinking balance never reaches zero in a finite number of years. On the worked asset at 40%, the book value after year 5 is $777.60, while prime cost has expensed the full $10,000. In practice the tail is closed by a salvage floor above zero, a switch to prime cost, or a write-off on disposal.
No. It builds the schedule in full years. Some tax formulas, including the Australian diminishing value formula, multiply by days held / 365, so an asset bought mid-year claims less in year 1 than this schedule shows. Use the schedule for the pattern and the comparison, and your tax formula for the actual claim.
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References
- Australian Taxation Office, "Prime cost and diminishing value methods" - the official formulas for both methods, including the diminishing value rate of base value x days held / 365 x 200% / effective life. ATO: Prime Cost and Diminishing Value Methods. Accessed October 2026.
- Internal Revenue Service, Publication 946, "How to Depreciate Property" - MACRS declining balance classes, the switch to straight-line, and the conventions United States tax depreciation applies. IRS: Publication 946, How to Depreciate Property. Accessed October 2026.
- IFRS Foundation, IAS 16, "Property, Plant and Equipment" - the international standard covering diminishing balance as a depreciation method and systematic allocation over useful life. IFRS Foundation: IAS 16, Property, Plant and Equipment. Accessed October 2026.
- Australian Taxation Office, "General depreciation rules: capital allowances" - the parent guidance for decline in value of depreciating assets, effective life, and cost base rules. ATO: General Depreciation Rules, Capital Allowances. Accessed October 2026.
- Internal Revenue Service, "A Brief Overview of Depreciation" - the IRS small business summary of depreciable property and the difference between expensing and capitalizing. IRS: A Brief Overview of Depreciation. Accessed October 2026.
- Internal Revenue Service, Instructions for Form 4562, "Depreciation and Amortization" - how declining balance and other depreciation deductions are computed and claimed on a United States return. IRS: Instructions for Form 4562. Accessed October 2026.