How to Calculate Depreciation
Depreciation is the systematic allocation of an asset's cost over its useful life. It reflects the gradual wearing out, consumption, or obsolescence of tangible assets — from office computers and machinery to vehicles and buildings. Understanding how to calculate depreciation correctly is essential for accurate financial statements, tax planning, and sound business decision-making.
What Is Depreciation and Why It Matters
When a business buys a long-term asset — a computer, a delivery van, a piece of manufacturing equipment — it does not expense the full cost immediately. Instead, accounting rules require spreading that cost across the asset's useful life through depreciation.
Depreciation matters for three key reasons:
- Accurate profit reporting: Matching the cost of an asset to the revenue it generates in each period gives a true picture of profitability.
- Tax reduction: Annual depreciation is a deductible business expense, reducing taxable income each year.
- Asset valuation: Tracking accumulated depreciation shows the net book value (carrying value) of your assets on the balance sheet.
Step-by-Step: How to Calculate Depreciation
- Determine the asset cost: Record the full acquisition cost — purchase price plus delivery, installation, and any other costs needed to put the asset into service.
- Estimate the salvage value: The salvage (or residual) value is what you expect the asset to be worth at the end of its useful life. If you plan to use it until it has no value, enter $0.
- Determine the useful life: How many years will the asset remain in productive use? Use IRS MACRS tables, manufacturer specifications, or industry conventions.
- Choose a depreciation method: Select the method that best reflects how the asset loses value. Straight-line is simplest; declining balance matches assets that depreciate faster early on; units of production is best when usage varies significantly.
- Calculate the annual depreciation charge: Apply the formula for your chosen method (see below). This figure is your annual depreciation expense.
- Record in your accounts: Each accounting period, debit Depreciation Expense and credit Accumulated Depreciation. The net book value = Original Cost − Accumulated Depreciation.
The Three Main Depreciation Methods
The three most commonly used depreciation methods each suit different asset types and accounting goals:
1. Straight-Line Depreciation
The simplest and most widely used method. The same amount is expensed every year.
2. Declining Balance Depreciation
Applies a fixed percentage rate to the asset's remaining book value each year. This front-loads the depreciation expense, which is realistic for assets like vehicles and computers that lose value quickly when new.
Depreciation Rate = 1 ÷ Useful Life × Multiplier (commonly 2× for double-declining balance)
3. Units of Production Depreciation
Ties depreciation directly to actual usage — ideal for machinery or vehicles where wear is driven by hours run or miles driven rather than time.
Comparison of All Three Methods
| Feature | Straight-Line | Declining Balance | Units of Production |
|---|---|---|---|
| Annual charge | Equal every year | Decreasing over time | Varies with usage |
| Complexity | Low | Medium | Medium |
| Best for | Buildings, furniture, IP | Vehicles, computers, tech | Machinery, production equipment |
| Tax benefit timing | Spread evenly | Front-loaded (early years) | Linked to production volume |
| Reflects actual wear? | Approximate | Good for tech assets | Most accurate |
Real-World Example: Office Laptop
Asset Details
- Cost: $1,500
- Salvage value: $150
- Useful life: 3 years
- Depreciable base: $1,350
Straight-Line Result
- Year 1: $450
- Year 2: $450
- Year 3: $450
- Total: $1,350
Straight-line calculation:
Double-declining balance (200% DB): The depreciation rate is 2 ÷ 3 = 66.67%.
Year 2: $500 × 66.67% = $333
Year 3: Remaining $167 (book value reaches salvage)
Notice how double-declining balance front-loads the deduction: $1,000 in year 1 versus $450 under straight-line. Over three years the total is the same ($1,350), but the timing of tax savings differs significantly.
US Tax Rules: Section 179 and MACRS
The US tax system provides two powerful tools for business asset depreciation:
Section 179 Expensing
Section 179 allows businesses to deduct the full purchase price of qualifying equipment and software in the year of purchase rather than depreciating it over years. The 2024 limit is $1,160,000 (phased out dollar-for-dollar above $2,890,000 in total purchases). This is ideal for small businesses needing an immediate tax reduction.
MACRS (Modified Accelerated Cost Recovery System)
MACRS is the standard US tax depreciation system. It assigns assets to property classes with predetermined useful lives and uses declining balance switching to straight-line:
- 5-year property: Computers, automobiles, light trucks
- 7-year property: Office furniture, fixtures, most manufacturing equipment
- 15-year property: Land improvements, fences
- 39-year property: Commercial real estate
Bonus Depreciation
In addition to Section 179, bonus depreciation allows an additional first-year deduction on qualified property. The percentage has been phasing down from 100% (2017–2022): 80% in 2023, 60% in 2024, and continuing to decrease through 2027. Consult a tax advisor for the current rate.
Calculate Depreciation Instantly
Use our free Depreciation Calculator to compute annual depreciation, accumulated depreciation, and net book value for any asset — with a full year-by-year schedule and support for all three methods.
Open Depreciation CalculatorFrequently Asked Questions
What is the simplest depreciation method?
Straight-line depreciation is the simplest method. Subtract the salvage value from the asset cost and divide by the useful life in years. For example, a $10,000 machine with a $1,000 salvage value and a 5-year useful life depreciates by $1,800 per year.
What is the difference between straight-line and declining balance depreciation?
Straight-line spreads the cost evenly over the asset's life. Declining balance front-loads depreciation — it applies a fixed rate to the remaining book value each year, resulting in higher deductions early on and smaller amounts later. Declining balance better reflects how many assets lose value faster when new.
What is Section 179 depreciation in the US?
Section 179 of the US tax code allows businesses to deduct the full cost of qualifying equipment or software in the year of purchase, rather than depreciating it over several years. The 2024 deduction limit is $1,160,000. This is especially useful for small businesses that need to reduce taxable income immediately.
How does depreciation affect taxes?
Depreciation is a non-cash expense that reduces taxable income. By recording annual depreciation, businesses lower their reported profit and therefore pay less tax in the current period. Accelerated methods (like declining balance) provide larger tax deductions earlier, improving early-year cash flow.
What is the useful life of an asset?
Useful life is the estimated period over which an asset provides economic benefit. The IRS publishes standard useful lives: computers (5 years), office furniture (7 years), commercial real estate (39 years). You can also use the manufacturer's specifications and your own usage patterns to estimate useful life.