What is a retirement growth calculator?
A retirement growth calculator estimates a future balance from money already saved, a monthly contribution and an expected annual return you enter. This NumberMotive version compounds monthly and shows total contributions, estimated growth, years remaining and the share of the projected balance that came from money put in.
The result is an educational estimate from the numbers you type. It is not financial advice, investment advice, retirement advice, a guaranteed return or an official retirement projection.
How retirement growth is modeled here
The model uses monthly compounding only. The annual return is divided by 12. Current savings grow as a lump sum. Monthly contributions are treated as deposits at the end of each month (an ordinary annuity). The horizon is the years until retirement you enter, converted to months.
Current age and retirement age are optional labels. They do not change the math. If both ages are entered and the gap does not match the years field, the estimate still uses the years field.
The formulas this calculator uses
Monthly rate r = expected annual return ÷ 100 ÷ 12
Months n = years until retirement × 12.
Current savings after growth when r is greater than 0 and n is greater than 0:
current × (1 + r)^n
Contribution growth when r is greater than 0 and n is greater than 0:
PMT × [((1 + r)^n − 1) ÷ r]
When the expected return is 0%, current savings stay at the entered amount and contributions add as cash only: PMT × n. When years are 0, the projected balance equals current savings. The calculator does not divide by zero and does not return NaN or Infinity.
Projected balance = grown current savings + grown contributions.
Total contributions = monthly contribution × n (cash added after today, not including the starting balance).
Estimated growth = projected balance − current savings − total contributions.
Contribution percentage = (current savings + total contributions) ÷ projected balance, or 100% when the projected balance is $0.00.
Worked example
With $50,000.00 already saved, a $500.00 monthly contribution, a 7% expected annual return and 25 years, there are 300 months. Current savings grow to $286,270.91. Contributions grow to $405,035.85. The projected retirement balance is $691,306.76. Total contributions are $150,000.00. Estimated growth is $491,306.76. Contribution percentage is 28.93%.
Entering current age 40 and retirement age 65 matches those 25 years as a label only. Changing the years field changes the math even if the ages stay the same. None of those inputs is a recommended savings plan or a guaranteed return.
What this calculator does not include
- Inflation, taxes, fees or required minimum distributions
- Social Security, pensions or other income in retirement
- Employer match, profit sharing or catch-up contribution rules
- Withdrawal, spending or longevity modeling
- A recommended return, asset allocation or retirement age
- An official Social Security, IRS or plan-provider projection
Limitations of this calculator
- Results are estimates based only on the numbers and optional ages you enter.
- The model assumes a constant monthly rate and a constant monthly contribution.
- A 0% return or a 0-year horizon does not produce Infinity or NaN.
- Very large combinations are rejected when a result leaves the safe numeric range.
- Scenarios are not saved, emailed or sent to analytics.
Frequently asked questions
What is a retirement growth calculator?
It estimates a future retirement balance from current savings, a monthly contribution and an expected annual return you enter. This NumberMotive version compounds monthly and also shows total contributions, estimated growth, years remaining and contribution percentage. It is an educational worksheet, not a retirement plan.
How is the projected retirement balance calculated?
Current savings grow as a lump sum with monthly compounding. Monthly contributions grow as an ordinary annuity. The two grown amounts are added. With $50,000.00 saved, $500.00 each month, 7% and 25 years, the projected balance is $691,306.76.
What expected annual return should I enter?
Enter the annual percentage you want to model. The calculator does not look up market returns, recommend an allocation or guarantee a result. 0% is valid and treats growth as $0.00.
How does monthly compounding work here?
The annual return is divided by 12. There are 12 modeled periods in each year. Years until retirement are multiplied by 12 to get the number of months. Other frequencies are not offered on this page.
What if the expected annual return is 0%?
A 0% return is valid. Current savings stay at the entered amount. Monthly contributions add as cash only. Estimated growth is $0.00.
What if the monthly contribution is $0?
A $0.00 monthly contribution is valid. Only current savings compound. Total contributions are $0.00. The projected balance equals the grown starting amount.
What if current retirement savings are $0?
A $0.00 starting balance is valid. Only monthly contributions grow. The projected balance equals the grown contributions.
What if years until retirement is 0?
A 0-year horizon is valid. The projected balance equals current savings. No monthly deposits are modeled. The calculator does not divide by zero and does not return Infinity or NaN.
How is total contributions calculated?
Total contributions are the monthly contribution multiplied by the number of months. The starting balance is not included in that total. It appears separately as current savings.
How is estimated growth calculated?
Estimated growth is the projected balance minus current savings minus total contributions. It is the modeled gain above money put in. It is not a guaranteed return.
How is contribution percentage calculated?
Contribution percentage is current savings plus total contributions, divided by the projected balance. If the projected balance is $0.00, the percentage is 100%. It describes the mix in this worksheet, not a recommended savings rate.
How do current age and retirement age affect the result?
Ages are optional labels. Leave both blank, or enter both. They do not change the math. If the age gap differs from the years field, the estimate still uses the years you entered.
Does this include Social Security, pensions or employer match?
No. The worksheet models only the savings, contribution and return you type. It does not add Social Security, a pension, an employer match or other retirement income.
Does this include inflation, taxes or withdrawals?
No. There is no inflation adjustment, tax, fee or withdrawal model. The projected balance is a pre-withdrawal educational figure from the inputs you chose.
Is the expected return a guaranteed investment return?
No. The rate is a planning assumption you type. Markets vary. The calculator does not guarantee a return or recommend an investment.
Is this result financial advice or an official retirement projection?
No. It is an educational estimate from numbers you chose. It is not financial advice, investment advice, retirement advice or an official Social Security, IRS or plan-provider projection.
Last reviewed August 24, 2026 (UTC).