Depreciation Calculator

About Depreciation Calculator

How Does Depreciation Work?

When a business buys an asset like a machine, vehicle, or piece of equipment, accounting rules do not allow it to deduct the full cost in the year of purchase (with some tax exceptions noted below). Instead, the cost is spread across the asset's useful life. The portion of the cost allocated to each accounting period is called the depreciation expense. Under IAS 16 (the IFRS standard governing property, plant and equipment), companies must review the useful life, residual value, and depreciation method of each asset at least once per financial year and adjust prospectively if expectations change.

The depreciable amount is the original cost minus the salvage value (also called residual value). Salvage value is the estimated amount the asset will be worth at the end of its useful life. Only this net amount gets depreciated - not the full purchase price.

The Four Depreciation Methods

Method	Formula (annual)	Pattern	Best For
Straight-line	(Cost - Salvage) / Useful Life	Same amount every year	Assets that lose value evenly (furniture, buildings)
Declining balance	Book Value x (1 / Useful Life) x factor	Higher in early years, decreasing	Assets that lose value faster initially
Double declining balance (DDB)	Book Value x (2 / Useful Life)	Aggressive early depreciation	Technology, vehicles, equipment that becomes obsolete quickly
Sum-of-years digits (SYD)	(Cost - Salvage) x (Remaining Years / SYD Sum)	Decreasing fractions each year	Assets that are most productive when new

Straight-line divides the depreciable amount equally across all years. It is the most common method for financial reporting because of its simplicity. Declining balance applies a fixed percentage rate to the remaining book value each year, producing larger charges early on. Double declining balance uses twice the straight-line rate for even more aggressive front-loading. Sum-of-years digits calculates a weighted fraction for each year based on the remaining useful life, giving a smooth curve between aggressive and even depreciation.

Worked Example: $50,000 Machine, 5-Year Life, $5,000 Salvage

Depreciable amount = $50,000 - $5,000 = $45,000.

Year	Straight-Line	DDB	SYD
1	$9,000	$20,000	$15,000
2	$9,000	$12,000	$12,000
3	$9,000	$7,200	$9,000
4	$9,000	$4,320	$6,000
5	$9,000	$1,480	$3,000
Total	$45,000	$45,000	$45,000

All methods depreciate the same total amount ($45,000). The difference is timing - accelerated methods front-load the expense, reducing taxable income more in early years. In Year 1, DDB claims $20,000 versus $9,000 under straight-line. By Year 5 the positions reverse, with DDB recognising only $1,480. Over the full period, cumulative depreciation is identical.

How Each Method Calculates

Method	Year 1 Calculation	Notes
Straight-line	$45,000 / 5 = $9,000	Same every year
DDB	$50,000 x (2/5) = $20,000	Applied to book value (not depreciable amount), capped at salvage
SYD	$45,000 x (5/15) = $15,000	SYD sum = 5+4+3+2+1 = 15. Year 1 fraction = 5/15

For DDB, the rate is always 2 divided by the useful life (2/5 = 40% in this example). That percentage is applied to the current book value, not the original cost. The depreciation stops in any year where it would push the book value below salvage.

For SYD, the sum of the digits 1 through n equals n(n+1)/2. With a 5-year life that gives 15. Year 1 uses fraction 5/15, Year 2 uses 4/15, and so on, creating a smoothly declining expense curve.

Common Asset Useful Life Estimates

Under IRS MACRS (Modified Accelerated Cost Recovery System), assets are assigned to property classes with fixed recovery periods. These are the most common classes from IRS Publication 946:

Asset Type	MACRS Recovery Period	Common Accounting Life	Typical Method
Computers and peripherals	5 years	3-5 years	DDB or straight-line
Office furniture and fixtures	7 years	7-10 years	Straight-line
Automobiles and light trucks	5 years	5-7 years	DDB
Manufacturing equipment	7 years	7-15 years	SYD or DDB
Commercial buildings (non-residential)	39 years	25-40 years	Straight-line
Residential rental property	27.5 years	25-30 years	Straight-line
Software licences	3 years (off-the-shelf)	3-5 years	Straight-line
Leasehold improvements	15 years	Lease term or useful life (shorter)	Straight-line

MACRS recovery periods are set by the IRS for US tax purposes. Accounting useful life under GAAP or IFRS may differ because it is based on the entity's own judgment about how long the asset will be productive.

Tax Depreciation: UK and US Rules

Tax authorities have their own depreciation rules that often differ from accounting depreciation.

United States: For 2026, the IRS Section 179 deduction allows businesses to immediately expense up to $2,560,000 of qualifying equipment, with a phase-out beginning at $4,090,000 in total equipment purchases. On top of Section 179, the One Big Beautiful Bill Act reinstated 100% bonus depreciation for 2025 and beyond, letting businesses deduct the full cost of eligible new or used assets in the year they are placed in service. These provisions mean many US businesses can write off equipment immediately rather than depreciating it over multiple years.

United Kingdom: HMRC does not use accounting depreciation methods for tax. Instead, businesses claim capital allowances. The Annual Investment Allowance (AIA) gives 100% tax relief on up to 1,000,000 per year of qualifying plant and machinery. For companies paying corporation tax, full expensing (made permanent from the 2023 Autumn Statement) allows 100% first-year deduction on main-rate plant and machinery. From April 2026, the main-rate writing-down allowance drops from 18% to 14% per year, with a new 40% first-year allowance introduced for main-rate expenditure. The special rate pool (long-life assets, integral features, cars over 50g/km CO2) remains at 6% per year.

When to Use Accelerated Depreciation

Scenario	Recommended Method	Why
High current-year income	DDB	Maximises deduction now, reducing current tax bill
Asset loses value fast (tech)	DDB or SYD	Matches the actual decline in usefulness
Steady, predictable use	Straight-line	Simplest to calculate and explain, matches even usage
Preparing for sale or audit	Straight-line	Produces the smoothest P&L and is easiest for investors to understand
HMRC / IRS compliance	Depends on jurisdiction	Tax authorities may require specific methods for certain asset classes

Many businesses maintain two sets of depreciation records: one for financial reporting (often straight-line) and one for tax returns (often accelerated). The difference between the two creates a deferred tax liability on the balance sheet.

Second Worked Example: $120,000 Delivery Van, 7-Year Life, $10,000 Salvage

Depreciable amount = $120,000 - $10,000 = $110,000.

Straight-line: $110,000 / 7 = $15,714.29 per year. Book value drops evenly from $120,000 to $10,000 over 7 years.

DDB: Rate = 2/7 = 28.57%. Year 1: $120,000 x 0.2857 = $34,286. Year 2: $85,714 x 0.2857 = $24,490. Year 3: $61,224 x 0.2857 = $17,493. The annual charge falls each year as the book value shrinks, and in later years the depreciation is capped so the book value does not drop below the $10,000 salvage.

SYD: Sum of digits 1 through 7 = 7 x 8 / 2 = 28. Year 1 fraction = 7/28, so depreciation = $110,000 x 7/28 = $27,500. Year 2 = $110,000 x 6/28 = $23,571. Each year the numerator drops by one, giving a smooth decline.

With DDB, over 66% of the total depreciation is recognised in the first three years. Under straight-line, only 43% is recognised by that point. That timing difference can significantly affect reported profits and tax liability in early years.

Book Value vs Market Value

Depreciation reduces the book value (accounting value) of an asset, but the market value (what it could sell for) may be quite different. A company car might have a book value of $5,000 after four years of depreciation but a market value of $8,000. The book value is used for financial statements and tax calculations, while market value matters for insurance, resale, and collateral assessments.

When an asset is sold for more than its book value, the difference is a taxable gain. If the book value is $5,000 and the asset sells for $12,000, the $7,000 difference is recognised as income. In the UK, this is called a balancing charge. In the US under MACRS, it is recaptured as ordinary income up to the original cost. For vehicle-specific depreciation estimates, the car depreciation calculator models real-world resale curves by make, age, and mileage.

Depreciation and Financial Ratios

Depreciation affects several important financial metrics. EBITDA (Earnings Before Interest, Taxes, Depreciation, and Amortisation) strips depreciation out to show operational cash-generating ability. Return on assets (ROA) divides net income by total assets, and since depreciation reduces both the numerator (net income) and the denominator (asset book values), the method chosen can move ROA in either direction depending on the asset's age.

Capital-intensive industries like manufacturing, mining, and transport tend to have much higher depreciation charges relative to revenue than service businesses. A factory might depreciate 8-12% of revenue each year, while a software company might depreciate less than 1%. Comparing companies across industries without normalising for depreciation policy can be misleading.

Common Mistakes When Calculating Depreciation

Forgetting to subtract salvage value is the most frequent error. Straight-line and SYD both work on the depreciable amount (cost minus salvage), not the full cost. DDB is an exception: it applies the rate to the full book value but then caps at salvage to prevent over-depreciation.

Another common mistake is confusing the depreciation rate with the straight-line rate. A 5-year life gives a straight-line rate of 20%. DDB doubles that to 40%, but this 40% is applied to the declining book value, not the original cost. The actual dollar amount decreases each year even though the rate stays the same.

Using the wrong useful life is another pitfall. A business that estimates 10 years for a laptop it will replace in 3 years will understate early expenses and overstate profits. IAS 16 requires that useful life estimates be reviewed annually and adjusted if expectations change. Getting this wrong does not just affect one year - it compounds across the entire asset life.

Finally, some businesses forget that depreciation is a non-cash expense. It reduces reported profit and taxable income but does not reduce the cash balance. A business with high depreciation charges can still be cash-flow positive. For evaluating the return on your asset investment, the ROI calculator shows return on investment. For understanding your overall business cost structure, the break-even calculator includes fixed costs like depreciation in its analysis.

Sources

• IRS Publication 946 - How To Depreciate Property (MACRS)
• IRS - Section 179 Deduction and Bonus Depreciation
• GOV.UK - Capital Allowances (AIA and Full Expensing)
• IFRS Foundation - IAS 16 Property, Plant and Equipment
• Investopedia - Depreciation Methods
• GOV.UK - Budget 2025 (Writing-Down Allowance Changes)