Retirement Savings Calculator

Estimate the lump sum needed at retirement from today's monthly spending, inflation and returns before and after retirement, then find the extra saving needed each month.

Annual rates are converted to compound monthly rates: (1 + rate)^(1/12) − 1. The first retirement month = today's spending × (1 + inflation)^years to retirement. The lump sum is the present value of withdrawals at the start of each month that rise with inflation, discounted at the post-retirement return. Existing savings grow at the pre-retirement return; the remaining gap is converted into equal end-of-month deposits until retirement.

A simple case: THB 20,000 a month, no inflation or return, 25 years of retirement. You need 20,000 × 300 = THB 6,000,000. With 30 years left to save, that is 6,000,000 ÷ 360 = THB 16,666.67 a month. If inflation equals the post-retirement return, the lump sum is exactly the first month's spending × the number of months.

This is a constant-rate model. Real returns fluctuate and can be negative. Taxes, fees, large medical costs and pensions not deducted from spending are excluded. If you expect a social security or civil service pension, enter spending after that income. This is not personal investment advice.