What Is Straight Line Depreciation?
Straight line depreciation (SLD) is a method of allocating the cost of a fixed asset — net of its estimated salvage value — in equal annual (or periodic) amounts over the asset’s estimated useful life. Each period, the same depreciation charge reduces the asset’s net book value by the same amount, following a straight, linear path from original cost to salvage value.
Organizations apply this depreciation method most commonly across industries and accounting frameworks because it matches expense recognition to time-based consumption. As a result, it provides a reasonable approximation for assets that wear out gradually and uniformly, such as buildings, furniture, fixtures, and many classes of machinery.
TL;DR
Straight-line depreciation allocates an asset’s depreciable cost in equal amounts across each period of its useful life. As a result, it remains the most widely used method because it is simple to calculate, easy to audit, and well-suited for assets that deliver consistent economic benefits over time. The formula is: Annual Depreciation = (Cost − Salvage Value) / Useful Life.
The Straight Line Depreciation Formula
Input | Description |
| Cost | Total capitalized cost — purchase price plus freight, installation, duties, and any other direct costs to bring the asset to its usable state |
| Salvage Value (Residual Value) | The estimated amount the asset will be worth at the end of its useful life (often zero for many asset classes) |
| Useful Life | Estimated period over which the asset will deliver economic benefit, expressed in years or months |
| Annual Depreciation | (Cost − Salvage Value) / Useful Life |
| Depreciation Rate (%) | (1 / Useful Life) × 100 — the percentage of depreciable cost charged each year |
Worked Example
Item | Detail |
| Asset | Office fit-out (leasehold improvements) |
| Cost | $1,99,181 |
| Salvage Value | $ 0 (no resale value at end of lease) |
| Useful Life | 6 years (lease term) |
| Annual Depreciation | $1,99,181 / 6 = $33,197 per year |
| Monthly Depreciation | $3,197 / 12 = $267 per month |
Depreciation Schedule:
| Year | Opening NBV | Depreciation Charge | Closing NBV |
| Year 1 | $19,181 | $3,197 | $15,984 |
| Year 2 | $15,984 | $3,197 | $12,788 |
| Year 3 | $12,788 | $3,197 | $9,591 |
| Year 4 | $9,591 | $3,197 | $6,394 |
| Year 5 | $6,394 | $3,197 | $3,197 |
| Year 6 | $3,197 | $3,197 | $0 |
Accounting Journal Entry for Straight Line Depreciation
Each period, the depreciation charge is recorded as follows:
- Debit: Depreciation Expense (Income Statement) — $3,197
- Credit: Accumulated Depreciation (Balance Sheet — contra asset) — $3,197
The asset remains on the balance sheet at its gross cost ($19,181). Accumulated depreciation increases each period, and organizations present it as a deduction from gross cost to arrive at net book value. This presentation preserves the historical cost record while showing the carrying amount net of charges.
Straight Line vs. Written-Down Value (WDV / Declining Balance)
| Factor | Straight Line Depreciation | Written-Down Value (Declining Balance) |
| Depreciation pattern | Equal charge every period | Higher early years, declining over time |
| Calculation base | Original depreciable cost (fixed) | Opening book value each period (declining) |
| Book value curve | Linear decline to salvage value | Exponential decline — never technically reaches zero |
| Income statement impact | Consistent expense over life | Front-loaded expense; lower in later years |
| Best fit | Assets with uniform benefit over time | Assets that lose value faster in the early years |
| Simplicity | Very simple — one calculation for the whole life | Slightly more complex — recalculated each period |
When to Use Straight Line Depreciation
- Buildings and structures — Physical wear is gradual and relatively uniform over decades.
- Furniture and fixtures — Usage pattern is typically stable and consistent across the asset’s life.
- Leasehold improvements — Depreciated over the lease term, which is a defined period with no residual value.
Assets with stable usage patterns are ideal for straight-line depreciation. Teams can apply straight-line depreciation with confidence when an asset’s economic benefits are consumed evenly over time. Straight-line depreciation is less appropriate for assets that lose value rapidly in the early years, such as IT equipment and vehicles, or for assets whose wear depends on output rather than time, such as mining equipment and moulds.
Best Practices for Straight Line Depreciation
- Review useful life estimates annually and revise them when evidence shows the asset will be used for a longer or shorter period than originally estimated. This way, teams apply prospective adjustments and prevent cumulative reporting errors.
- Set salvage value realistically at the point of capitalization — zero salvage value is appropriate for many asset classes, but overriding this assumption for assets with genuine residual value leads to excessive depreciation charges.
- Apply the method consistently across all assets in the same class — switching from straight-line to WDV for individual assets without a policy change creates audit flags.
- Record partial-year depreciation accurately when assets are acquired or disposed of mid-period. For precision, teams should pro-rate depreciation by the actual days or months the asset remains in service.
How AssetCues Handles Straight Line Depreciation
AssetCues calculates straight-line depreciation for each asset based on configured cost, salvage value, and useful life. As a result, it generates asset-level depreciation schedules in monthly or annual periods and updates them whenever teams revise useful life or salvage value assumptions. In addition, period-end depreciation reports feed directly into ERP and general ledger workflows.
CA Sunny Shah
