Your retirement corpus, month by month: a dated depletion ledger with a sensitivity table — under your assumptions, on your machine
corpusclock turns five numbers — your corpus, your monthly spend, an annual return rate, an annual inflation rate and a start month — into a dated, month-by-month ledger showing exactly when the money runs out, plus a return-by-inflation sensitivity grid. Every result is labelled under your assumptions. It is a month-by-month retirement corpus depletion calculator with dates — not a forecast, not advice, just arithmetic you can check by hand.
How the depletion ledger works
Each month the withdrawal is taken at the start. If the balance cannot cover
it, the corpus depletes that month. Otherwise the spend is subtracted and
interest is added on the remainder at your annual return ÷ 12. The
monthly spend steps up once a year by your inflation rate. Everything is computed
in integer paise, so the parts reconcile exactly.
A worked example
A ₹30,00,000 corpus, spending ₹30,000 a month, at a
8% return and 6% inflation from 2026-08,
lasts 113 months and depletes in 2036-01 under those
assumptions — the month-114 withdrawal has grown to ₹50,684.37 and
the balance can no longer cover it.
| Return \ Inflation | 4% | 6% | 8% |
|---|---|---|---|
| 6% | 2035-11 | 2035-03 | 2034-08 |
| 8% | 2036-12 | 2036-01 | 2035-04 |
| 10% | 2038-06 | 2037-02 | 2036-02 |
Illustrative sensitivity grid for the example above — each cell is the depletion month for that rate pair, a what-if, not a plan.
Why "under your assumptions"
Nobody can tell you what markets will do, so corpusclock does not try. You supply every rate; it applies one flat monthly rate and shows the consequence. It ignores tax, fees, one-off expenses and healthcare shocks. This is not financial advice — it is a ledger you can verify.
Try it below
The calculator below opens with sample scenarios you can edit or replace. Nothing you type leaves this page.