SWP Calculator

The SWP Calculator shows how long your money will last under a Systematic Withdrawal Plan — a strategy where you withdraw a fixed amount every month from a lump sum that keeps earning a return. Enter your corpus, monthly withdrawal and expected return, and the tool tells you the exact number of years and months your corpus survives, your balance over time, and whether your withdrawal is sustainable or is drawing down your principal.

What is a Systematic Withdrawal Plan (SWP)?

A Systematic Withdrawal Plan is the mirror image of a SIP (Systematic Investment Plan). Instead of paying money in, you take money out: you invest a lump sum once, then withdraw a fixed amount at regular intervals — usually monthly — while the remaining balance continues to grow. SWPs are popular for turning a retirement corpus, an inheritance, or a matured mutual-fund investment into a predictable income stream, while keeping the unused balance invested.

SWP Formula

The key question is how many months a corpus lasts. With a constant monthly withdrawal, the balance after \( n \) months follows the annuity drawdown formula:

where \( P \) is the corpus, \( W \) is the monthly withdrawal and \( i \) is the monthly return rate (annual return ÷ 12). Setting the balance to zero and solving for \( n \) gives the number of months the corpus lasts:

This formula only works when the withdrawal is larger than the income the corpus earns (that is, \( W > P \times i \)). When \( W \le P \times i \), the corpus never runs out — the withdrawals are fully covered by returns, so the plan is self-sustaining. When you add an annual step-up, the withdrawal rises each year, so this calculator simulates the plan month by month for an exact answer.

The Sustainable Withdrawal Threshold

The single most important number in an SWP is the sustainable withdrawal: the monthly income your corpus generates by itself. It is roughly the corpus multiplied by the monthly return rate.

If you withdraw at or below this level, returns cover your withdrawals and your principal stays intact — the money can last indefinitely. Withdraw above it and you start eating into the principal, so the corpus will eventually run dry. The gauge in the results shows exactly where your withdrawal sits relative to this threshold.

Example: How Long Will 1,000,000 Last?

Suppose you invest a corpus of 1,000,000 and withdraw 8,000 per month, expecting an 8% annual return. The monthly return rate is 8% ÷ 12 ≈ 0.667%, so the corpus earns about 6,667 per month at the start. Because your 8,000 withdrawal is larger than that, you are drawing down the principal — and the formula above gives a duration of about 22 years and 6 months. Drop the withdrawal to 5,000 (below the 6,667 the corpus earns) and the plan becomes self-sustaining: the balance actually grows over time.

SWP vs SIP: What is the Difference?

What Affects How Long Your Corpus Lasts?

How to Use This Calculator

1. Enter your corpus and withdrawal: Pick your currency, then enter the lump sum you have invested and the fixed amount you want each month.
2. Enter your expected return: Add the annual return you expect, and optionally an annual step-up so your withdrawals rise with inflation.
3. Choose a projection period: Select how many years to project and click Calculate.
4. Review your results: See how long your corpus lasts, the balance-over-time chart, the sustainable-withdrawal gauge, the totals withdrawn and earned, and a year-by-year breakdown.

Frequently Asked Questions

What is a Systematic Withdrawal Plan (SWP)?

A Systematic Withdrawal Plan lets you withdraw a fixed amount of money at regular intervals (usually monthly) from a lump sum you have invested, while the remaining balance keeps earning a return. It is commonly used to turn a retirement corpus or mutual-fund investment into a steady income stream.

How long will my corpus last with an SWP?

It depends on the size of your corpus, your monthly withdrawal, and the return you earn. If your withdrawal is less than the income the corpus generates each month, it can last indefinitely. If your withdrawal is larger, the corpus is gradually drawn down and eventually runs out. This calculator shows the exact number of years and months.

How is the SWP duration calculated?

With a constant withdrawal the number of months is n = ln(W / (W − P × i)) / ln(1 + i), where P is the corpus, W is the monthly withdrawal and i is the monthly return rate. When W is less than or equal to P × i the corpus never depletes. With an annual step-up the plan is simulated month by month.

What is a sustainable SWP withdrawal?

A withdrawal is sustainable when it is at or below the income your corpus earns, which is roughly the corpus multiplied by the monthly return rate. At that level returns fully cover your withdrawals and the principal is preserved, so the money can last indefinitely.

What is a step-up SWP?

A step-up SWP increases your withdrawal amount by a fixed percentage every year so your income keeps pace with inflation. Because the withdrawals rise over time, a step-up SWP depletes the corpus faster than a flat withdrawal of the same starting amount.

Is SWP income taxable?

Tax treatment of SWP withdrawals depends on your country and the type of investment. In many places only the capital-gains portion of each withdrawal is taxed, not the full amount. This calculator shows pre-tax figures, so check the rules that apply to you for an after-tax estimate.

Additional Resources

• Systematic Investment Plan - Wikipedia
• Annuity - Wikipedia