Straight-Line Depreciation Calculator
Book depreciation the simple way: cost minus salvage, spread evenly over the useful life, starting the month it goes into service — by fiscal year, with the journal entries.
Ben / Reviewed Sep 27, 2026 / v2.0.0
Results
Showing the numbers you calculated- Monthly depreciation
- $750.00
- $9,000.00 for a full year
- First-year depreciation
- $6,750.00
- Fiscal 2026 · 9 months
- Depreciable base
- $45,000.00
- Cost − salvage value
- Fully depreciated
- 12/31/2031
- End of fiscal 2031
- Life in months
- 60
Depreciation schedule
Swipe the table sideways to see all 6 columns.
| Fiscal year | Year ends | Months | Depreciation | Accumulated | Book value |
|---|---|---|---|---|---|
| 2026 | 12/31/2026 | 9.0 | $6,750.00 | $6,750.00 | $43,250.00 |
| 2027 | 12/31/2027 | 12.0 | $9,000.00 | $15,750.00 | $34,250.00 |
| 2028 | 12/31/2028 | 12.0 | $9,000.00 | $24,750.00 | $25,250.00 |
| 2029 | 12/31/2029 | 12.0 | $9,000.00 | $33,750.00 | $16,250.00 |
| 2030 | 12/31/2030 | 12.0 | $9,000.00 | $42,750.00 | $7,250.00 |
| 2031 | 12/31/2031 | 3.0 | $2,250.00 | $45,000.00 | $5,000.00 |
Suggested journal entries
Suggested entries for your records — adjust account names to your chart of accounts.
| Account | Debit | Credit |
|---|---|---|
| 12/31/2026 — Fiscal 2026 depreciation (9 months) | ||
| Depreciation expense | $6,750.00 | |
| Accumulated depreciation | $6,750.00 | |
| Totals | $6,750.00 | $6,750.00 |
| A full month of depreciation (for monthly closes) | ||
| Depreciation expense | $750.00 | |
| Accumulated depreciation | $750.00 | |
| Totals | $750.00 | $750.00 |
What this does
It spreads the cost of an asset evenly over the years you'll use it — the depreciation most small businesses use for their books. You get the amount for each fiscal year, the running accumulated depreciation, and the book value, starting in the month the asset actually went into service.
The spreadsheet does the same with formulas, including partial first and last years, so you can change the life or salvage value and watch it re-spread.
How the math works
The basic formula:
monthly depreciation = (cost − salvage value) ÷ useful life in months
Then each fiscal year gets the months the asset was in service that year. The first year is usually partial (from the in-service month to year-end), and so is the last one.
depreciation to date = (cost − salvage) × months used ÷ life months (rounded to the cent) this year = to date − last year's to date
Working from depreciation-to-date means the rounding never piles up — the last year trues up to exactly the salvage value.
Straight-line for the books and MACRS for taxes is completely normal. The two numbers are supposed to be different.
Check my math: a worked example
A $50,000 asset with a $5,000 salvage value and a 5-year life, placed in service 04/15/2026.
- Depreciable base: $50,000 − $5,000 = $45,000.00.
- Per month: $45,000.00 ÷ 60 months = $750.00 ($9,000.00 for a full year).
- Fiscal 2026: 9 months → $6,750.00.
- Fiscal 2027: 12 months → $9,000.00.
- It's fully depreciated at the end of fiscal 2031, when book value hits $5,000.00.
These numbers come straight from the calculator using its example inputs — if the math ever changes, this example changes with it.
Mistakes I see a lot
- Taking a full year of depreciation in the year you bought it (unless that's your written policy).
- Forgetting salvage value — or setting it higher than the asset could ever sell for.
- Using the tax life (MACRS class) as the book life. Book life is your honest estimate of how long you'll use it.
- Depreciating land. Land doesn't wear out, so it's never depreciated.
Questions people ask
- Full-month, mid-month, or half-year?
- Pick one policy and use it for every asset. Full-month (start in the month placed in service) is the most common for books; half-year is simpler if you only book depreciation once a year.
- What if my fiscal year doesn't end in December?
- Pick your year-end month. The first year runs from the in-service month to that year-end, and years are named for the calendar year they end in.
- What's the monthly journal entry?
- Debit depreciation expense, credit accumulated depreciation, for the monthly amount shown. Accumulated depreciation is a contra-asset that sits under the asset on the balance sheet.
- Does the spreadsheet recalculate?
- Yes. Change the cost, salvage, life, in-service date, convention (1–4), or year-end month, and the schedule and entries re-run.
Assumptions and limits
- Book (GAAP) straight-line: (cost − salvage) ÷ useful life, on a months basis. This isn't tax depreciation — for that, see the MACRS calculator.
- Full-month convention by default: the month the asset goes into service counts as a full month. Mid-month, half-year, and full-first-year conventions are available as book policies.
- Depreciation to date is always (cost − salvage) × months used ÷ life months, rounded to the cent, so each year is the difference and the final year lands exactly on salvage value.
- Years are fiscal years ending in the month you pick; a fiscal year is named for the calendar year it ends in.
- No impairments, disposals, or changes in estimate (see the Asset Book Value tracker for those).
Disclaimer: Educational and planning use only. Results depend on what you enter and may not match your lender, your tax return, or professional accounting treatment. Informational content + opinions only — not tax/legal advice.