What the SWP Calculator does
This SWP calculator shows how long a lump sum lasts when you withdraw a fixed amount from it every month, with an optional yearly increase in the withdrawal and a return you assume on the money that stays invested. It gives the time until the money runs out, the balance left after the years you plan for, the total withdrawn and earned, the largest monthly withdrawal that would last the whole period, and a year-by-year table with a month-by-month CSV.
A systematic withdrawal plan (SWP) is the mutual-fund term for redeeming a set amount at regular intervals - typically used for a retirement income or to pay school fees from a fund you have built up. The same arithmetic applies to any drawdown from savings. The calculator simulates every month instead of using a shortcut formula, so the step-up and the final part-payment are handled exactly. It works in the browser, fetches no fund data and promises no return: the rate is yours to choose.
How to use it
- Enter the starting amount (your corpus) and how much you want to withdraw each month. Indian digit grouping such as 50,00,000 is fine.
- Enter a yearly step-up if you want the withdrawal to rise with prices - 5 means each year's monthly amount is 5% more than the year before. Leave it at 0 for a flat amount.
- Enter the yearly return you expect on the money that stays invested, and how many years the plan must cover.
- Open "How the return and the withdrawal are timed" if you want to change the conventions: an effective yearly return (the default, matching how fund returns are quoted) or a nominal rate divided by 12, and withdrawals at the end or start of each month.
- Read how long the money lasts, the balance left at the end of your plan, and the largest starting withdrawal that would last the full period. Download the monthly schedule if you want to check or chart it yourself.
Reading the results
The headline counts full monthly withdrawals. When the balance can no longer cover a whole withdrawal, the last payment is whatever is left; it is shown separately so you can see exactly when the plan stops working.
"Largest start that lasts" is the withdrawal that leaves the balance at zero exactly at the end of your plan, with your step-up applied. Withdrawing less leaves money over; withdrawing more runs out early. With a step-up, the starting figure is lower than a flat amount would be, because later withdrawals are bigger.
If the return on the remaining money is larger than what you take out, the balance never falls and the result reads 100+ years. That is the case where you are living off the growth alone.
Worked example: 10 lakh at 15,000 a month
Take a corpus of ₹10,00,000, a withdrawal of ₹15,000 at the end of each month and a return of 1% a month (12% a year, nominal). In month one the money grows by 10,000 to 10,10,000 and the withdrawal leaves 9,95,000, so the balance falls by 5,000 - and a little faster each month, because there is less left to earn on.
The closed formula for when the money runs out is n = ln(W ÷ (W − rP)) ÷ ln(1 + r) = ln(15,000 ÷ 5,000) ÷ ln(1.01) = 1.0986 ÷ 0.00995 = 110.4 months. The calculator agrees: 110 full withdrawals (9 years 2 months), then a final ₹6,162 in month 111.
To last exactly 10 years at the same rate, the monthly withdrawal is P × r ÷ (1 − (1 + r)^−120) = 10,000 ÷ (1 − 0.30299) = ₹14,347. If the 12% is an effective yearly return instead, the monthly rate is 0.949% and the sustainable figure drops to ₹13,995.
Formulas and scoring rules
- Monthly rate from a yearly return R
effective: r = (1 + R)^(1/12) − 1; nominal: r = R ÷ 1210% effective is 0.7974% a month; 12% nominal is 1% a month, which is 12.68% over a year.- Withdrawal in month m with a yearly step-up s
w(m) = W × (1 + s)^floor((m − 1) ÷ 12)- Balance each month
end of month: B = B × (1 + r) − w; start of month: B = (B − w) × (1 + r)When B cannot cover w, the final withdrawal is what is left and the plan ends.- Months until the money runs out (no step-up, end of month)
n = ln(W ÷ (W − rP)) ÷ ln(1 + r), when W > rPShown for checking; the calculator simulates month by month.- Withdrawal that lasts N months (no step-up)
W = P × r ÷ (1 − (1 + r)^−N)With a step-up the calculator finds the figure by bisection on the simulation.- Rounding
no rounding inside the simulation; amounts are shown to the nearest whole unit and the CSV to two decimals
Why the order of returns matters
The calculator applies the same return every month. A real fund might average that return over 20 years and still leave you worse off, if the bad years come first. Withdrawals in a falling market sell more units at low prices, and those units are not there to recover. This is called sequence-of-returns risk. A common way to allow for it is to test a lower return, keep a year or two of withdrawals in a low-risk fund, or withdraw a little less than the largest figure shown.
Tax, exit loads and inflation
Each SWP payment is a redemption of units, so part of it can be a taxable capital gain, depending on how long the units were held and the country's rules. Exit loads may apply to units sold within a fund's stated period. Neither is modelled here; check your fund's scheme documents and your tax position.
Inflation is handled only through the step-up. A flat withdrawal buys less every year; a step-up near the inflation rate keeps its spending power roughly constant, at the cost of running the money down faster.
Limitations: what the result does not prove
- The return is a constant assumption. Mutual funds and markets do not deliver a steady rate, and past returns do not predict future ones.
- Taxes, exit loads, fund expense changes and any lump-sum withdrawals are not included.
- The simulation stops at 100 years. A plan that is still going then is reported as lasting 100+ years.
- It is an illustration of the arithmetic, not financial advice, and not a recommendation of any fund or withdrawal rate.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- SEBI Investor Website - mutual funds and systematic plans
- Association of Mutual Funds in India (AMFI) - investor information
- Investor.gov (US SEC) - Compound interest calculator and explanation
Frequently asked questions
How long will my money last with monthly withdrawals?
It depends on the corpus, the withdrawal and the return. ₹10 lakh earning 1% a month with ₹15,000 taken out at the end of each month lasts 110 full months - just over 9 years - with a smaller final payment in month 111. Enter your own figures to see the month it runs out.
What is a good SWP withdrawal rate?
There is no universal figure. The safe amount depends on how many years the money must last, what it can reasonably earn and how much you need it to rise each year. The calculator shows the largest starting withdrawal that lasts your chosen period at your assumed return - withdrawing less than that leaves a margin for poor returns.
How does a step-up SWP work?
The monthly withdrawal stays the same for twelve months, then rises by the step-up percentage, and so on each year. ₹30,000 a month with a 5% step-up becomes ₹31,500 a month in year two and about ₹38,288 in year six. It keeps pace with rising costs but uses up the corpus faster.
Why does my SWP calculator give a different answer?
Usually because of the monthly rate convention. Many calculators divide the yearly rate by 12, which over a year earns more than the stated rate (12% becomes 12.68%). Fund returns are normally quoted as effective yearly rates, which this calculator uses by default. Withdrawal timing - start or end of the month - also shifts the result slightly.
Can I live off the returns without touching the capital?
Only if the monthly withdrawal is no more than what the remaining money earns each month. At 1% a month, ₹1,00,000 supports ₹1,000 a month indefinitely, in theory. With a step-up or a lower return the capital starts to fall. When growth covers the withdrawals, the result shows 100+ years.
Is SWP better than a fixed deposit for monthly income?
They carry different risks. A deposit's interest is fixed for its term; an SWP's value moves with the market, so the assumed return here is not guaranteed and capital can fall. Tax also works differently. This calculator only shows the withdrawal arithmetic; it does not compare products or recommend one.
Last reviewed by the A2Z.Tools team against the sources listed above.
