Straight-Line Depreciation Explained, With a Worked Example

Learning how to calculate depreciation with the straight-line method is one of the more approachable pieces of business accounting — a fixed dollar amount written off every year, for the same amount, for the asset’s entire useful life.

The formula

A worked example

A $20,000 asset with a $2,000 estimated salvage value and a 5-year useful life depreciates by ($20,000 − $2,000) ÷ 5 = $3,600/year. After 2 years, book value is $20,000 − ($3,600 × 2) = $12,800. A $30,000 asset with $3,000 salvage and an 8-year life depreciates $3,375/year, reaching $19,875 book value after 3 years. The Depreciation Calculator runs this for any cost, salvage value, and useful life.

Why book value and market value diverge

Book value follows the depreciation schedule mechanically, independent of the asset’s actual real-world condition or resale market. A well-maintained piece of equipment might hold real market value above its book value; a piece of equipment that becomes technologically obsolete faster than expected might be worth far less on the resale market than its book value suggests. This divergence is normal and expected — book value is an accounting convention for spreading cost over time, not a real-time market appraisal.

Straight-line vs. other depreciation methods

Method	Pattern
Straight-line	Equal amount every year
Declining balance	Larger write-offs early, smaller later
Units of production	Tied to actual usage/output rather than time

Straight-line is the simplest and most widely used method for financial reporting specifically because of its predictability — the same amount every year makes forecasting and comparison across periods straightforward, even though it doesn’t always track an asset’s real value loss pattern as precisely as an alternative method might for assets that lose value faster in early years (like most vehicles and technology equipment).

Estimating salvage value and useful life honestly

Both salvage value and useful life are estimates made at the time an asset is acquired, not certainties — and how conservatively or optimistically they’re set directly affects the annual depreciation figure. A higher estimated salvage value or a longer useful life both reduce the annual depreciation expense, which can make near-term profitability look better on paper, but an unrealistic estimate in either direction eventually shows up as a mismatch between book value and reality once the asset is actually retired or sold. Reasonable, defensible estimates — often guided by industry norms for a given asset class — matter more than optimistic ones for keeping the depreciation schedule genuinely useful.

Tax treatment can differ from book depreciation

It’s worth flagging that the straight-line method used for financial reporting (the version this calculator models) doesn’t always match the depreciation method required or permitted for tax purposes in a given jurisdiction — many tax systems allow or require accelerated depreciation methods that front-load deductions into earlier years specifically as a tax incentive for capital investment. This means a business’s “book” depreciation schedule and its “tax” depreciation schedule can legitimately diverge, both being correct for their respective purposes — a detail worth confirming with a tax professional rather than assuming straight-line applies universally.

Depreciation’s role in broader business math

Depreciation is a non-cash expense that still affects a business’s profitability calculations and, by extension, its break-even point — if depreciation is counted as part of fixed costs, it raises the units needed to break even, even though no actual cash changes hands for it in a given period. For a business owner tracking overall financial position, depreciating assets also affect net worth calculations, since business equipment should be counted at current book value, not original purchase price, when tallying total assets.

Depreciation across multiple assets

A business with many depreciable assets — equipment, vehicles, computers, furniture — typically tracks each on its own depreciation schedule rather than depreciating a lumped total, since different asset categories usually carry different useful-life estimates and purchase dates. Aggregating individual schedules into a total annual depreciation figure for financial statements is straightforward once each asset is tracked separately, but attempting to depreciate a combined pool of dissimilar assets as a single unit tends to produce a far less accurate picture of any individual asset’s true remaining book value.

FAQ

Does depreciation involve an actual cash payment each year? No — it’s a non-cash accounting expense that spreads an asset’s original cost over its useful life; the cash was spent (or financed) when the asset was purchased, not annually thereafter.

What happens to book value once an asset outlives its useful life estimate? It stays flat at the salvage value — depreciation stops accumulating once the asset’s book value reaches its estimated salvage floor, even if it remains in active use.

Why choose straight-line over an accelerated depreciation method? Simplicity and predictability for financial reporting purposes — accelerated methods can better match real-world value loss for assets that lose value fastest early on, but straight-line’s flat, easily forecasted schedule is often preferred for its clarity.

Can the same asset use straight-line for books but a different method for taxes? Yes — this is common and legitimate, since financial reporting and tax reporting serve different purposes and are often governed by different rules in a given jurisdiction.

Does depreciation apply to land as well as buildings? Generally no — land itself is typically treated as non-depreciating, since it doesn’t wear out or become obsolete the way buildings, equipment and vehicles do; only the structures and improvements on the land are depreciated.