What Is Depreciation?
Depreciation is the accounting process of spreading an asset's cost over its useful life rather than expensing it all at once. Buy a $10,000 machine that will last five years, and instead of recording a $10,000 expense in year one, you record $1,800 per year (under Straight-Line) — matching the cost to the period the machine actually generates revenue.
Two different depreciation systems exist side by side in US accounting. Book depreciation (what this calculator computes) follows Generally Accepted Accounting Principles (GAAP) and appears on financial statements. Tax depreciation follows IRS rules under the Modified Accelerated Cost Recovery System (MACRS) and determines your actual deduction on a tax return. They often produce different numbers — a business can legally use Straight-Line for its books and an accelerated method for taxes simultaneously. Reference: IRS Publication 946 — How to Depreciate Property
How to Use This Calculator
- Asset Cost — the original purchase price, including any installation or setup costs that are capitalized
- Salvage Value — the estimated value at the end of useful life (also called residual value). Enter 0 if you expect the asset to have no value at retirement.
- Useful Life — how many years the asset will be used. IRS provides useful life guidelines by asset class in Publication 946, but book depreciation can use management's best estimate.
- Depreciation Method — Straight-Line for even expenses, Double Declining Balance or SYD for front-loaded deductions
- Click "Calculate Depreciation Schedule" to see Year 1 figures and the complete year-by-year table
The 3 Depreciation Formulas
Each method produces the same total depreciation over the asset's life — the difference is when that depreciation is recorded:
Method Comparison — Same Asset, Three Schedules
Using the same $10,000 asset ($1,000 salvage, 5-year life), here's how book value differs year by year across all three methods. Every figure matches the live calculator's output exactly:
| Year | SL Depreciation | SL Book Value | DDB Depreciation | DDB Book Value | SYD Depreciation | SYD Book Value |
|---|---|---|---|---|---|---|
| 1 | $1,800 | $8,200 | $4,000 | $6,000 | $3,000 | $7,000 |
| 2 | $1,800 | $6,400 | $2,400 | $3,600 | $2,400 | $4,600 |
| 3 | $1,800 | $4,600 | $1,440 | $2,160 | $1,800 | $2,800 |
| 4 | $1,800 | $2,800 | $864 | $1,296 | $1,200 | $1,600 |
| 5 | $1,800 | $1,000 | $296 | $1,000 | $600 | $1,000 |
| Total | $9,000 | — | $9,000 | — | $9,000 | — |
All three methods depreciate the same $9,000 over five years — the total is always Cost minus Salvage Value. DDB records $4,000 in Year 1 vs SL's $1,800 — a $2,200 difference that reduces taxable income earlier when using an accelerated method for tax purposes.
Which Depreciation Method Should You Use?
The right choice depends on whether you're computing for financial reporting, tax purposes, or both — and what the asset actually does:
| Method | Best For | Tax Advantage | Income Statement Effect |
|---|---|---|---|
| Straight-Line (SL) | Buildings, furniture, assets that wear evenly | None — spreads evenly | Steady, predictable expense each year |
| Double Declining Balance (DDB) | Vehicles, computers, tech equipment | Higher deductions in early years reduce taxable income sooner | Higher expense early, lower later |
| Sum-of-Years-Digits (SYD) | Assets that generate more value early in life | Moderate front-loading vs DDB | Decreasing expense, smoother than DDB |
MACRS — The US Tax Depreciation Standard
For federal income tax purposes, most US businesses use the Modified Accelerated Cost Recovery System (MACRS) rather than the three book methods above. MACRS uses IRS-prescribed recovery periods and rates — for a $10,000 asset in the 5-year class (computers, cars, light equipment), the tax deductions look like this:
| Year | MACRS Rate | Deduction ($10,000 asset) | Cumulative |
|---|---|---|---|
| 1 | 20.00% | $2,000 | $2,000 |
| 2 | 32.00% | $3,200 | $5,200 |
| 3 | 19.20% | $1,920 | $7,120 |
| 4 | 11.52% | $1,152 | $8,272 |
| 5 | 11.52% | $1,152 | $9,424 |
| 6 | 5.76% | $576 | $10,000 |
Notice that a "5-year" MACRS asset actually spans 6 tax years because of the half-year convention — IRS assumes assets are placed in service at mid-year. Also note: MACRS uses no salvage value; you depreciate the full cost to zero. Reference: IRS Publication 946 | SBA — Business Tax Guidance
Real-World Examples by Asset Type
| Asset | Typical Life | Common Method | Example: $35,000 vehicle, $5,000 salvage, 7 yr SL |
|---|---|---|---|
| Commercial vehicle | 5–7 years | DDB or MACRS (5-yr) | SL: $4,286/yr | DDB Y1: $10,000 | Book after Y1: $25,000 |
| Office equipment / computers | 3–5 years | DDB or MACRS (5-yr) | $5,000 laptop, $0 salvage, 3 yr SL: $1,667/yr |
| Commercial building | 39 years (IRS) | Straight-Line only | $500,000 building: $12,821/yr (MACRS 39-yr) |
| Manufacturing equipment | 7–15 years | SYD or DDB | $50,000 machine, $5,000 salvage, 10 yr SL: $4,500/yr |
| Furniture / fixtures | 7 years | Straight-Line (GAAP) | $8,000 furniture, $500 salvage, 7 yr SL: $1,071/yr |
For the $35,000 vehicle with $5,000 salvage over 7 years: Straight-Line gives exactly $4,285.71 per year. Double Declining Balance at 28.57% (2÷7) gives $10,000 in Year 1 with book value dropping to $25,000 immediately — useful if the business wants larger deductions while the vehicle is newer and more valuable.
5 Practical Tips for Business Depreciation
- Section 179 can eliminate the calculation entirely for small assets. Under IRS Section 179, businesses can deduct the full cost of qualifying equipment — up to a limit the IRS adjusts annually, so check the current-year figure — in the year of purchase instead of depreciating it. For a $10,000 piece of equipment, Section 179 gives a $10,000 deduction in Year 1 vs DDB's $4,000. Check IRS Publication 946 for current limits and qualifying property rules.
- Track the depreciable base, not just the annual amount. The depreciable base is always Cost minus Salvage Value — $9,000 in the primary example. The annual amount varies by method, but every method must reach exactly the salvage value at the end of useful life. If your schedule doesn't end at salvage value, the inputs or formula are wrong.
- DDB often switches to Straight-Line in later years. In practice, companies using DDB switch to Straight-Line when SL produces a higher deduction than DDB — maximizing the deduction each year. In the $10,000 / 5-year example, Year 5 DDB gives only $296 vs SL's $1,800 equivalent; a switch in Year 4 or 5 extracts more depreciation. Many accounting systems do this automatically.
- Partial-year depreciation matters for assets acquired mid-year. If an asset is placed in service on July 1, you get only half a year's depreciation in Year 1 under most conventions. Under MACRS, the half-year convention applies automatically — that's why the 5-year MACRS table spans 6 calendar years. For book purposes, prorate by months: an asset placed in service in September gets 4/12 of the annual amount in Year 1.
- Bonus depreciation (first-year expensing above the standard schedule) may apply for recent purchases. The Tax Cuts and Jobs Act of 2017 allowed 100% bonus depreciation before a scheduled phase-down began in later years. This is separate from Section 179 and has different rules about which property qualifies. The applicable percentage depends on the specific year an asset was placed in service and can be affected by later legislation, so verify the current rate in IRS Publication 946 or with a tax professional before assuming any particular percentage applies.