The retirement calculator projects existing savings and monthly contributions to a chosen retirement age using a constant assumed investment return. It is a simple planning tool for exploring how time and saving habits may affect a retirement fund.
How to use this calculator
Enter current age, target retirement age, current savings, monthly contribution, and assumed annual return. The number of monthly periods is the difference in ages multiplied by twelve. Contributions are modeled at the end of each month.
Formula & calculation method
Future value = current savings × (1 + i)^N + monthly contribution × [((1 + i)^N − 1) / i]The monthly rate i is the assumed annual nominal return divided by twelve. The first term projects current savings and the second projects the contribution series. At a zero return, future value is current savings plus all contributions.
Worked example
A person aged 30 targeting 65 has 420 monthly periods. The projection separates estimated final savings from total contributions, making it easier to see the assumed role of investment growth over that long horizon.
Why this is useful
The calculator allows quick testing of retirement age, contribution level, and return assumptions. It can show how starting earlier or increasing monthly savings changes the projected fund without requiring a complex model.
Limitations to keep in mind
This is not a complete retirement income plan. It excludes inflation, taxes, fees, pensions, withdrawals, variable returns, and contribution escalation. A constant return is a simplifying assumption, and actual outcomes may be substantially different.
Frequently asked questions
Does the result show how much I can spend annually?
No. It estimates a fund at retirement, not a sustainable withdrawal rate or retirement income stream.
Why does starting earlier matter?
An earlier start provides more compounding periods and usually more contributions, both of which can increase the projected balance.
Is the assumed return guaranteed?
No. It is only a scenario input. Investment returns fluctuate and actual net returns may be lower or negative.