How to use this calculator
- Enter your Current age and the Retirement age you are aiming for.
- Add Current retirement savings and your Monthly contribution.
- Set the Expected annual return and Inflation. Use cautious figures and test more than one.
- Choose a Withdrawal rate (the share of the pot you take out per year) and read the monthly income, both in future and in today's money.
How the projection works
The calculator grows your balance month by month. Each month the balance earns the monthly equivalent of your annual return and then your contribution is added. At retirement age it takes the pot, applies your withdrawal rate to get yearly income, and divides by twelve. Dividing the pot by (1 + inflation)^years shows what it is worth in today's money.
Balance(t+1) = Balance(t) × (1 + r_m) + C; Income = Balance × W / 12; Real = Balance / (1 + i)^years- r_m = (1 + annual return)^(1/12) − 1, the monthly return
- C = monthly contribution
- W = withdrawal rate (for example 4%)
- i = annual inflation rate; years = retirement age − current age
Money in the future buys less than money today, so the today's-money figures are the ones to judge your plan by.
Example: a 40-year-old planning for 65
Take someone aged 40 with $80,000 saved, contributing $800 a month, expecting 6% a year with 2.5% inflation and a 4% withdrawal rate. At 65 the pot reaches $884,380.81, of which $320,000 is contributions and $564,380.81 is growth. It could pay $2,947.94 a month, which is $1,590.09 a month in today's money.
That gap between nominal and real income is the main surprise for most people. The pot looks large, but 25 years of inflation cut its buying power by almost half.
What moves the result most
Changing one input at a time with the same example shows the levers. Working until 67 instead of 65 lifts the pot to $1,014,004.42, with $1,735.30 a month in today's money. Raising the contribution to $1,200 gives $1,154,896.41. A return of 4% instead of 6% drops the pot to $620,345.40.
Starting late costs the most. The same person at 50 with the same contributions ends with only $421,254.18 at 65. Time and compounding do more than the contribution amount, which is why starting early matters.
Turning the result into a decision
Compare the today's-money monthly income with the spending you expect in retirement. If there is a shortfall, you have four levers: contribute more, retire later, accept more risk for a higher return (which also raises the chance of a bad outcome), or plan to spend less. Use the FIRE calculator to work backwards from a spending target, and the inflation calculator to restate future costs.
Check whether your employer matches contributions and whether the account type gives a tax advantage. Details differ by country, so confirm them with your plan provider.
Limits of the projection
The calculator assumes a constant return, level contributions, no taxes on withdrawals and no fees. Real returns come in a different order each year, and a bad market early in retirement can hurt more than the average suggests. It also leaves out pensions, Social Security or other state benefits, one-off expenses, healthcare costs and how long you will live. Treat it as a planning aid and review the plan with a qualified adviser before making big decisions.
Frequently asked questions
How much do I need to retire?
It depends on your spending. A common starting point is annual spending divided by your withdrawal rate; the FIRE calculator does this directly.
What return should I assume?
Pick a cautious long-run figure after fees, then test a lower one. Returns are not guaranteed.
Why show two sets of numbers?
One is in future dollars and the other in today's money. The second tells you what the income will actually buy.
Is a 4% withdrawal rate safe?
It is a widely used rule of thumb, not a guarantee. A lower rate leaves more margin if you retire early or markets perform poorly.
Does the calculator include taxes?
No. Withdrawals from some accounts are taxed, so your take-home income may be lower than shown.