Book Value and Depreciation Calculator
Estimate carrying amount under straight-line or reducing-balance depreciation from cost, residual value, useful life, elapsed years and rate. Accounting policy and tax allowances can differ.
Enter asset depreciation assumptions
Carrying amount is an accounting estimate, not market value or a tax allowance schedule.
Cost and carrying amount
Asset cost includes amounts required to bring the asset to the location and condition necessary for intended use under the applicable accounting policy. Carrying amount is cost less accumulated depreciation and impairment, adjusted for any permitted revaluation model. The calculator starts with cost and models depreciation only.
Market value is different. A vehicle can have a carrying amount above or below the price obtainable on sale. Book value is an accounting measurement, not a guaranteed trade-in, insurance or liquidation value.
Residual value
Residual value estimates the amount an entity would currently obtain from disposal after disposal costs if the asset were already at the expected end-of-life age and condition, under the relevant standard. It reduces the depreciable amount. Entering zero assumes no residual value for this simple calculation.
Residual value is an estimate reviewed where required; it is not chosen merely to reduce expense. Market, technology and disposal obligations can change it. The script floors carrying amount at residual value and stops the annual benchmark once that floor is reached.
Useful life
Useful life reflects expected utility to the entity, not necessarily physical survival. Hours of use, output, maintenance, obsolescence, legal limits and replacement strategy can make it shorter than the manufacturer’s maximum life. A shared building component and a computer may therefore use very different lives.
The page accepts fractional years for scenario work. Actual accounts generally depreciate from when an asset is available for use and apply a period convention. Use acquisition, available-for-use and disposal dates for a precise schedule rather than rounding every asset to a whole year.
Straight-line method
Straight-line depreciation allocates cost minus residual value evenly across useful life. Annual expense is depreciable amount divided by life. Carrying amount after elapsed years is cost minus annual expense times elapsed years, subject to the residual floor.
This method suits an expected pattern of benefits that is even over time. It does not mean cash value declines evenly. If usage or output drives consumption, a units-of-production method may better reflect benefits, but that method needs measurable activity inputs absent here.
Reducing-balance method
Reducing balance applies a fixed percentage to the opening carrying amount, producing larger expense earlier and smaller expense later. The script estimates value as cost times one minus rate to the elapsed years, then applies the residual floor. The annual benchmark is rate times the displayed value while above the floor.
A 30% reducing rate is not automatically equivalent to a five-year straight-line life. Select a method and rate because they reflect benefit consumption and policy, not because one produces a preferred profit. A switch or estimate change requires appropriate prospective accounting treatment.
Accumulated depreciation
Accumulated depreciation is cost minus carrying amount in this simplified model. It is a contra-asset balance, not cash saved for replacement. An entity can record depreciation without setting aside any money, and replacement cost can rise independently.
Use a separate capital-replacement budget based on expected price and timing. Confusing accumulated depreciation with a funded reserve can leave a business unable to replace an essential asset even though the ledger appears to show a large accumulated amount.
Impairment and revaluation
Damage, obsolescence, weak demand or changed use can indicate that carrying amount is not recoverable. Impairment testing uses standards and cash-flow evidence beyond scheduled depreciation. The calculator does not reduce value for impairment or reverse one.
Some asset classes may use a revaluation model under the relevant reporting framework. Revaluation affects equity, profit and future depreciation according to detailed rules. Do not enter an arbitrary market estimate as cost simply to imitate revaluation.
Component depreciation
A significant asset can contain parts with different useful lives, such as a building structure, lift and roof. Component depreciation records them separately. One blended life can distort expense and disposal accounting when a component is replaced.
Create one calculation per material component using allocated cost, residual and life. When replacing a component, derecognise the old carrying amount where required. This calculator does not automate that schedule, but separating inputs makes the issue visible.
Accounting versus tax
Financial-statement depreciation follows the applicable accounting framework and estimates. South African tax deductions, allowances and recoupments follow tax legislation and SARS guidance. The tax base can therefore differ from carrying amount, creating deferred-tax considerations.
Do not use this book-value result as a SARS wear-and-tear claim. Identify the asset, ownership, trade use, allowance rate, start date and any private use under current tax rules. Maintain a fixed-asset register and tax schedule separately.
Disposal and gain or loss
On disposal, compare proceeds net of disposal costs with carrying amount at the disposal date to determine an accounting gain or loss, subject to the reporting framework. Update depreciation to the disposal date first. The result is not the same as taxable capital gain or recoupment.
Keep invoice, commissioning evidence, depreciation history, impairment records and disposal documentation. A reproducible asset register should reconcile opening cost, additions, disposals, depreciation, impairment and closing carrying amount for each reporting period.
Partial periods and rounding
The elapsed-years input can accept a fraction, so six months may be entered as 0.5 for an even time-apportionment scenario. Actual policy may use daily, monthly or full-month conventions and may stop depreciation when an asset is classified as held for sale or derecognised. Match the reporting framework and period dates.
Round journal entries consistently at the ledger level, not each hidden mathematical step. Many small assets rounded separately can create a reconciliation difference. Preserve unrounded schedule values or a clear rounding adjustment so the asset register agrees with the general ledger.
Asset-register controls
Assign a unique asset number and record description, location, custodian, serial number, cost, available-for-use date, method, life, residual value and disposal status. Conduct physical verification and investigate missing, idle or damaged items. A calculated schedule cannot establish that an asset still exists or remains in use.
Restrict changes to useful life, method and residual value to authorised users with review evidence. Reconcile additions to invoices and capital-project closure, and reconcile disposals to approvals and proceeds. Good controls prevent an elegant depreciation formula from being applied to duplicated, expensed or nonexistent assets.
Questions that affect this result
Is book value the same as resale value?
No. Carrying amount is an accounting measure; market price depends on the actual sale and asset condition.
Why does depreciation stop at residual value?
Residual value is excluded from depreciable amount under the entered assumptions.
Can I use the result for a SARS wear-and-tear claim?
No. Tax allowances and recoupments follow separate tax rules and dates.
When is straight-line unsuitable?
When the expected pattern of consuming benefits is materially uneven and another reliable method better represents it.
What if one asset has components with different lives?
Material components may need separate depreciation calculations and register records.