Depreciation Calculator
Straight-line or written-down value, with first-year pro-ration for an asset bought partway through the year — the detail that trips up most manual calculations.
Depreciation calculator
Straight-line or written-down value, with first-year pro-ration by months in use — plus the full year-by-year schedule, not just year 1.
| Period | Months | Opening | Charge | Closing |
|---|---|---|---|---|
| Year 1 | 6 | ₹1,20,00,000 | ₹6,00,000 | ₹1,14,00,000 |
| Year 2 | 12 | ₹1,14,00,000 | ₹12,00,000 | ₹1,02,00,000 |
| Year 3 | 12 | ₹1,02,00,000 | ₹12,00,000 | ₹90,00,000 |
| Year 4 | 12 | ₹90,00,000 | ₹12,00,000 | ₹78,00,000 |
| Year 5 | 12 | ₹78,00,000 | ₹12,00,000 | ₹66,00,000 |
| Year 6 | 12 | ₹66,00,000 | ₹12,00,000 | ₹54,00,000 |
| Year 7 | 12 | ₹54,00,000 | ₹12,00,000 | ₹42,00,000 |
| Year 8 | 12 | ₹42,00,000 | ₹12,00,000 | ₹30,00,000 |
| Year 9 | 12 | ₹30,00,000 | ₹12,00,000 | ₹18,00,000 |
| Year 10 | 12 | ₹18,00,000 | ₹12,00,000 | ₹6,00,000 |
| Year 11 | 6 | ₹6,00,000 | ₹6,00,000 | ₹0 |
Educational illustration only. A written-down-value schedule never mathematically reaches zero — it runs for the number of years you choose, not to a defined end point the way straight-line does.
Why the installation date matters more than the invoice amount
A machine costing ₹1.2 crore, installed 1 October, with a 10-year straight-line life, has an annual charge of ₹12 lakh. But it was only in use for 6 months of its first year — so the correct charge for that year is ₹12 lakh × 6⁄12 = ₹6 lakh, not the full ₹12 lakh. Charging a full year overstates depreciation (and understates profit); charging nothing understates depreciation (and overstates profit). Either error is found the same way: by checking the actual date the asset was ready for use, not the invoice date.
Straight-line vs written-down value
Straight-line charges the same amount every year: (Cost − Residual Value) ÷ Useful Life. Written-down value charges a fixed percentage of the asset’s remaining book value each year, so the charge is largest in year one and shrinks every year after — useful for assets that lose most of their value early (vehicles, computers) rather than wearing down evenly (buildings, furniture).
See the full method, with more worked examples
This calculator uses the same mid-year apportionment logic taught in Advanced Audit & Assurance, including how to spot a client that charged depreciation from the wrong date.