Retirement Calculator Guide: Formula & Worked Example
Short answer
Project your retirement savings and monthly income. In the fixed example below, savings at retirement is 772,315.45. Your answer depends on the inputs and assumptions you choose.
Formula
Result = Retirement Calculator calculation using current age, retirement age, current savings, monthly contribution, annual return, withdrawal rate
The inputs are current age, retirement age, current savings, monthly contribution, annual return, withdrawal rate. Use the input scale shown beside each field and keep time periods and units consistent. Only round the final result for display.
Worked example
- Current age
- 30
- Retirement age
- 60
- Current savings
- 20000
- Monthly contribution
- 500
- Annual return
- 7
- Withdrawal rate
- 4
- Savings at retirement: 772,315.45
- Monthly retirement income: 2,574.38
- Total contributions: 200,000.00
Understanding the result
Project your retirement savings and monthly income. Start with the base example, then replace each value with the figure that matches your situation.
Current age
The example uses 30 for current age. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Retirement age
The example uses 60 for retirement age. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Current savings
The example uses 20000 for current savings. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Monthly contribution
The example uses 500 for monthly contribution. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Annual return
The example uses 7 % for annual return. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
Withdrawal rate
The example uses 4 % / yr for withdrawal rate. This is an illustration, not a recommended value. Keep the unit and time period shown by the field.
What the comparison means
The comparison changes only current age, keeping every other example input fixed. This isolates that input's effect on the primary result. It does not predict future outcomes.
Rates, fees, eligibility, local tax rules and provider rounding can change the final amount. Reference tax and exchange-rate data may be outdated; verify the official source before deciding.
Comparison
| Scenario | Input | Result |
|---|---|---|
| Lower input | Current age: 24 | Savings at retirement: 1,218,581.43 |
| Base example | Current age: 30 | Savings at retirement: 772,315.45 |
| Higher input | Current age: 36 | Savings at retirement: 478,739.78 |
Common mistakes
- Using the wrong units for current age.
- Comparing results while changing more than one input at a time.
- Rates, fees, eligibility, local tax rules and provider rounding can change the final amount. Reference tax and exchange-rate data may be outdated; verify the official source before deciding.
Checklist
- Confirm current age.
- Confirm retirement age.
- Confirm current savings.
- Confirm monthly contribution.
- Confirm annual return is expressed in %.
- Check the result against your source or provider.
Calculators Percentage Editorial Team
Calculator guides from the Calculators Percentage team. These introductory examples are educational, not professional advice.
Last reviewed:
Rates, fees, eligibility, local tax rules and provider rounding can change the final amount. Reference tax and exchange-rate data may be outdated; verify the official source before deciding.