SLN in Excel: Straight-Line Depreciation and Period Alignment

=SLN(cost, salvage, life)

Cost is the initial amount, salvage the modeled value remaining at the end, and life the number of periods. All three arguments are required. Keep cost and salvage in the same currency and life in the same period unit as the schedule.

The independent arithmetic model is (cost−salvage)/life. SLN contains no current-period argument, so it does not know whether a formula has been copied beyond the intended lifespan. Nor does it choose an accounting policy, useful life, residual value or tax treatment.

Enter 18000 in B2, 3000 in B3 and 6 in B4. Label the cells Cost, Salvage and Life in years. Use:

=SLN(B2,B3,B4)
=(B2-B3)/B4

Both have expected value 2500. The amount allocated is 15000, not the full initial cost of 18000, because the model retains 3000 at the end.

If the result is 3000, inspect whether salvage was omitted from a hand-built comparison. Formatting as currency does not repair an incorrect depreciable base.

Put periods 1 through 6 in A10:A15. In B10 enter =SLN($B$2,$B$3,$B$4) and fill down. In C10 enter =$B$2-SUM($B$10:B10) and fill down.

Expected closing book values are 15500, 13000, 10500, 8000, 5500 and 3000. The total depreciation in B10:B15 is 15000, exactly the depreciable base before any rounding.

The dollar signs keep the input cells fixed. The expanding SUM range accumulates expenses through the current row. A seventh row would incorrectly allocate another 2500 unless the schedule is bounded or given an explicit period guard.

Six years contains 72 monthly periods. The formula =SLN(18000,3000,72) has expected value 208.333333333 per month. Twelve unrounded monthly values total 2500.

If each posted monthly amount is rounded to 208.33, 72 postings total 14999.76, leaving 0.24 of the intended base unallocated. A two-decimal display alone does not change stored values; ROUND does. Choose and document the posting convention, and reconcile any final-period adjustment separately.

Using life=6 in a 72-row monthly schedule would repeat an annual charge every month. A factor-of-twelve error is usually a unit mismatch, not an issue with SLN’s arithmetic.

For the same asset, =SYD(18000,3000,6,1) has an independently expected first-period expense of 4285.714285714. SLN allocates 2500 in that period. Over a complete six-period schedule, both models allocate the same 15000 base, but their timing differs.

Compare both the full schedule and ending balance. A method cannot be selected merely because it yields a preferred first-year expense; this example illustrates the mechanics rather than accounting eligibility.

For the ordinary asset model here, use positive life and salvage between zero and cost. Life zero makes the independent division undefined; the dedicated SLN reference does not specify the exact native error display, so none is invented here. A negative base needs investigation rather than automatic suppression.

If cost equals salvage and life is positive, the mathematical allocation is zero. If a blank or numeric-looking text reaches an argument, check the underlying cell type rather than assuming coercion. Native blank handling, invalid-input codes, extreme precision and every installation’s behavior remain unverified.

Audit the schedule using total expense, ending book value and period count together. A correct individual formula does not guarantee that the surrounding schedule is complete or bounded correctly.

• Current documentation: the dedicated Microsoft reference lists Excel for Microsoft 365, Excel for Microsoft 365 for Mac, Excel 2024, Excel 2024 for Mac, Excel 2021, Excel 2021 for Mac, Excel 2019, Excel 2016.
• Introduced: the first introduction version/build is not established by the dedicated reference used here.
• Last functioning version: unknown; a current help listing is not a last-working-build test.
• Evidence checked: October 15, 2026. Official documentation was freshly retrieved; examples were independently calculated. No native Excel, Mac or web-client execution was performed.

• Microsoft SLN reference.
• Microsoft function catalog and introduction-marker explanation.
• Editorial testing standards.

Examples use English function names and comma separators. Expected numbers are rounded independent mathematical calculations; documented error expectations are labeled as such. They are not captured Excel output. All illustrative data and policies are fictional.