以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Enter your current age, planned retirement age and a conservative life expectancy (planning to 90 or 95 is common).
- Enter current retirement savings and how much you contribute each month, plus any yearly increase.
- Set expected returns before and during retirement, and an inflation rate.
- Enter the yearly income you want in retirement in today's money, and other income such as a pension or social security.
計算式
Savings grow at the pre-retirement return with yearly contributions. The amount needed at retirement is the present value of withdrawals that rise with inflation each year, discounted at the post-retirement return.
Need at retirement = W₁ × (1 − q^N) / (1 − q), with q = (1 + inflation) / (1 + return)
W₁ = (desired − other income) × (1 + inflation)^(years to retirement)
Example
- Age 35, retiring at 65, saving $800/month (rising 2% a year) with $50,000 today at 6%.
- You want $60,000 a year in today's money and expect $20,000 from other sources, so savings must fund $40,000 a year (in today's money) for 25 years.
- The calculator compares your projected balance with the amount needed and shows any shortfall.
よくある質問
What is the 4% rule?
A guideline from US historical market data: withdrawing about 4% of savings in the first year, then adjusting for inflation, has historically lasted around 30 years. It is a rough rule, not a guarantee.
Why use different returns before and after retirement?
Many people shift towards lower-risk, lower-return investments as they approach and enter retirement.
Are taxes included?
No. Enter your desired income as a pre-tax amount if withdrawals will be taxed, or adjust it for your tax situation.