Asset Details

$
Original cost of the asset
$
Estimated value at end of useful life
years
Estimated useful life in years
units
Total production capacity over asset life
units
Units produced in the selected year
of 5
Year to show detailed results for
Depreciation Formulas
SL: (Cost - Salvage) / Life
DDB: (2 / Life) × Book Value
SYD: (Remaining / SYD Sum) × (Cost - Salvage)
Units: ((Cost - Salvage) / Total Units) × Units Used
Ryan O'Connell, CFA
Calculator by Ryan O'Connell, CFA

Depreciation Comparison — Year 1

Straight-Line
$18,000
Book Value $82,000
Accum. Dep. $18,000
Double Declining Balance
$40,000
Book Value $60,000
Accum. Dep. $40,000
Method DDB
Sum-of-Years'-Digits
$30,000
Book Value $70,000
Accum. Dep. $30,000
Units of Production
$21,600
Per-Unit Rate $0.18
Units Used 120,000

Formula Breakdown

Book Value Over Time

Annual Depreciation Expense

Full Depreciation Schedule

Year Straight-Line DDB SYD
Dep. Accum. Book Val. Dep. Accum. Book Val. Dep. Accum. Book Val.
Model Assumptions
  • Full first-year depreciation assumed (no half-year or mid-quarter convention)
  • DDB automatically switches to straight-line when SL exceeds DDB for remaining useful life
  • DDB never depreciates below salvage value
  • Units of Production assumes a linear relationship between usage and depreciation
  • No tax effects considered (book depreciation only)
  • Asset is placed in service at the beginning of Year 1

For educational purposes. Not financial advice. Book-depreciation assumptions simplified.

Understanding Depreciation Methods

What is Depreciation?

Depreciation is the systematic allocation of an asset's cost over its useful life. It reflects the consumption of the asset's economic benefits over time. The total amount depreciated equals the depreciable base: Cost minus Salvage Value.

Depreciable Base
Depreciable Base = Cost - Salvage Value
This is the total amount to be depreciated over the asset's life

Comparing Time-Based Methods

Straight-Line

Equal expense each year
Simplest method. Best when the asset provides equal utility each period. Used by the vast majority of companies for financial reporting.

Accelerated (DDB & SYD)

Higher expense in early years
Appropriate when an asset is most productive early in its life. DDB applies 2× the SL rate to declining book value. SYD uses a decreasing fraction each year.

Units of Production

Unlike time-based methods, Units of Production ties depreciation to actual usage. A per-unit rate is calculated as (Cost - Salvage) / Total Estimated Units, then multiplied by units produced each period. This method is common in mining, oil & gas, and manufacturing where asset wear depends on usage rather than time.

DDB Switch to Straight-Line

Under DDB, the book value may never reach salvage if the declining balance method is applied for the full life. Companies typically switch to straight-line when the SL depreciation on remaining book value exceeds the DDB amount. This ensures the asset depreciates exactly to its salvage value by the end of its useful life.

Tax vs. Book: For U.S. tax purposes, most companies use MACRS (Modified Accelerated Cost Recovery System), which has its own recovery periods and conventions. The methods in this calculator apply to book (financial reporting) depreciation per GAAP.

Frequently Asked Questions

The four primary depreciation methods are: (1) Straight-Line, which spreads cost evenly over the asset's useful life; (2) Double Declining Balance (DDB), an accelerated method that applies twice the straight-line rate to the declining book value; (3) Sum-of-Years'-Digits (SYD), another accelerated method using a decreasing fraction each year; and (4) Units of Production, which bases depreciation on actual usage rather than time.

Accelerated methods (DDB, SYD) are appropriate when an asset generates more economic benefit in its early years or when you want to match higher depreciation expense against higher early revenues. Straight-line is simpler and best when the asset provides equal utility each period. For tax purposes, accelerated depreciation can provide larger deductions in early years, deferring tax liability. Note that for U.S. tax reporting, MACRS is used rather than these book methods.

DDB switches to straight-line when the straight-line depreciation on the remaining book value exceeds the DDB amount. Each year, compare: (a) DDB = Rate × Book Value, vs. (b) SL for remaining life = (Book Value - Salvage) / Remaining Years. When (b) exceeds (a), switch to straight-line for that year and all remaining years. This ensures the asset depreciates exactly to salvage value by the end of its useful life.

The depreciable base is the total amount that will be depreciated over the asset's useful life. It equals Cost minus Salvage Value. For Straight-Line and SYD, this base is used directly in the formula. DDB is unique — it applies the rate to the full book value (not the depreciable base), but still cannot depreciate below salvage value.

Units of Production depreciation calculates a per-unit depreciation rate: (Cost - Salvage) / Total Estimated Units. Each period's depreciation equals this rate multiplied by actual units produced. This method is ideal for assets whose wear is driven by usage — such as vehicles measured by miles, or machinery measured by hours or units produced. Total depreciation over the asset's life cannot exceed the depreciable base.

Straight-line is by far the most common depreciation method for financial reporting. Surveys consistently show the vast majority of companies use straight-line for their books. Declining balance and SYD are used by a small minority, while Units of Production is used primarily in mining, oil and gas, and manufacturing. For U.S. tax purposes, most companies use MACRS (Modified Accelerated Cost Recovery System), which differs from these book depreciation methods.
Disclaimer

This calculator is for educational purposes only and computes book depreciation under GAAP methods. Actual depreciation may vary based on tax regulations (e.g., MACRS), partial-period conventions, impairment testing, and company-specific policies. Consult a professional accountant for specific depreciation decisions.

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