Retirement Calculator - Required Savings | Financial Calculator

Free retirement calculator to find how much you need to save. Enter desired monthly income, return rate, and period to calculate your retirement fund goal.

A reverse calculation, not a savings plan

Most calculators project savings forward; this one works backward. You state the retirement income you want, and it returns the lump sum that must already be invested on day one of retirement to sustain it. Two modes are offered: a drawdown annuity that spends principal and returns to zero, and an interest-only perpetuity (M ÷ r) that leaves the principal intact for heirs or as a safety margin.

Worked example at a hypothetical return

To draw $3,000 per month for 20 years with funds earning 4% annually, the calculator's annuity formula requires $495,065.57 at the start — noticeably less than the $720,000 of raw withdrawals, because the balance keeps compounding. The interest-only mode for the same income needs $900,000 ($3,000 ÷ 0.333% monthly). Both figures are pre-tax and informational, not financial advice.

How to Use

  1. Desired Monthly Income — Enter the monthly amount you want your savings to pay out in retirement, for example $3,000
  2. Annual Return Rate — Enter the expected average annual return (%) on funds that stay invested during retirement
  3. Withdrawal Period — Enter how many years or months the payouts should last — 20 years equals 240 monthly withdrawals
  4. Interest Only Option — Check this to compute the larger nest egg needed to live on returns alone, preserving principal forever
  5. Calculate — Click Calculate to see the total retirement fund required at the start of withdrawals
  6. Refine With Real Returns — Subtract expected inflation from your nominal return and recalculate to express the goal in today's money

FAQ

Should I factor in inflation for retirement planning?

Yes, use the real return rate (nominal return minus inflation) for accurate results. For example, 5% nominal minus 2% inflation = 3% real return.

When should I use the Interest Only option?

Use this to preserve principal for heirs or as a permanent safety net. Required savings will be higher but your wealth remains intact.

How do I account for Social Security or pension income?

Subtract your expected monthly Social Security or pension from your desired income. Enter only the additional amount you need from personal savings.

What formula determines the required savings?

The present value of an annuity: M × ((1+r)^n − 1) ÷ (r(1+r)^n), where M is the monthly withdrawal, r the monthly rate (annual ÷ 12), and n the number of months. It assumes the remaining balance stays invested while being drawn down.

What happens to the principal over the withdrawal period?

In the standard mode the balance declines every month and reaches roughly zero with the final withdrawal. With the Interest Only option the principal never shrinks — withdrawals equal the monthly return, so the fund can pay out indefinitely.

Why does the required amount fall when the return rate rises?

Because the untouched balance keeps earning while you withdraw. At a 0% return you would need the full M × n (for example $720,000 to draw $3,000 monthly for 240 months); any positive return lets growth cover part of every withdrawal.