Your Retirement Inputs

years
Your current age
years
Age you plan to retire
years
Plan conservatively — longer is safer
$
Total in all retirement accounts today
$
Monthly amount you contribute to retirement
$
Monthly employer matching contribution
%
Nominal annual return (e.g., 7 for 7%)
%
Expected average annual inflation rate
$
Annual income needed in retirement (today's dollars)
$
Expected monthly Social Security benefit (today's dollars)
Key Formulas
Real Return = (1 + r) / (1 + i) − 1
Nest Egg = Income Gap × PV Annuity Factor
Gap = Target − Projected Savings
r = nominal return | i = inflation | All income figures in today's dollars
Ryan O'Connell, CFA
Calculator by Ryan O'Connell, CFA

Retirement Analysis

On Track
Required Nest Egg (today's $) $0
Inflation-Adj. Target (future $) $0
Projected Savings $0
Surplus / (Shortfall) $0
Years to Retire 0
Years in Retire 0
Income Gap (annual) $0
Add'l Monthly Needed $0/mo
Desired Income (annual) $0
SS Coverage (annual) $0

Portfolio Value Over Time

Required vs. Projected

Sensitivity Analysis

Shows surplus/(shortfall) at different return and contribution levels.

Model Assumptions

  • Constant nominal return throughout accumulation period
  • Constant real return during retirement drawdown
  • Constant inflation rate for entire planning horizon
  • Constant monthly contributions (no salary growth modeled)
  • Social Security benefit in today's dollars (assumed inflation-adjusted by SSA), beginning at retirement age
  • Single-life model — no spousal or survivor benefits
  • No taxes on withdrawals modeled
  • No required minimum distributions (RMDs) modeled
  • Employer match assumed constant (no vesting schedule)
  • Contributions treated as end-of-month (ordinary annuity)
For educational purposes only. Not financial advice. Retirement planning involves many variables not captured by a deterministic model — consult a certified financial planner for personalized guidance.

Understanding Your Retirement Savings Gap

What Is a Retirement Savings Gap?

A retirement savings gap is the difference between the nest egg you need at retirement and the amount your current savings trajectory will produce. If your projected savings fall short of the target, the gap tells you exactly how much more you need to save each month to get on track.

This calculator uses a deterministic model: it computes a single target based on your inputs and compares it to your projected savings. For a probability-based analysis that accounts for market uncertainty, see the Retirement Monte Carlo Calculator.

How the Nest Egg Target Is Calculated

The calculator determines how much income your savings must produce each year (after Social Security), then computes the lump sum needed to sustain those withdrawals through your full retirement period:

Required Nest Egg (today's dollars)
Nest Egg = Annual Income Gap × PV Annuity Factor
where PV Annuity Factor = [1 − (1 + rreal)−n] / rreal

The result is in today's dollars — it reflects the purchasing power you need. The calculator then inflates this to future dollars (the nominal amount at retirement) so it can be compared directly to your projected nominal savings.

The Real Rate of Return

The real rate of return strips out inflation to show how fast your money grows in purchasing power:

Fisher Equation
Real Return = (1 + Nominal Return) / (1 + Inflation) − 1
Example: (1.07) / (1.03) − 1 = 3.88%

Social Security's Role

Social Security reduces the burden on your personal savings. The calculator subtracts your expected annual Social Security income from your desired retirement income. Only the remaining “income gap” must be funded by your nest egg. If Social Security covers your entire income need, no additional savings are required.

Social Security is assumed to begin at your specified retirement age and to be inflation-adjusted by the SSA over time.

On Track Badge Thresholds

Badge Condition
On TrackSurplus ≥ 0 (projected meets or exceeds target)
CloseShortfall < 10% of target
BehindShortfall 10–30% of target
Far BehindShortfall > 30% of target
Deterministic vs. Probabilistic: This calculator assumes a constant return each year. In reality, returns vary. For a probability-based analysis that simulates thousands of market scenarios, use the Retirement Monte Carlo Calculator.

Frequently Asked Questions

The amount depends on your desired annual income, expected Social Security benefits, planned retirement length, and expected investment returns. This calculator uses the present value of an annuity formula to determine the lump sum needed to fund your retirement income for the full retirement period, then adjusts for inflation to give you a target in future dollars. The result is specific to your inputs rather than relying on a single rule of thumb.

A retirement savings gap is the difference between the amount you need at retirement (your target nest egg) and the amount you are projected to accumulate based on your current savings and contribution rate. If projected savings exceed the target, you have a surplus. If the target exceeds projected savings, you have a shortfall, and this calculator shows exactly how much more you need to save each month to close it.

Social Security reduces the amount you need to save personally. The calculator subtracts your expected annual Social Security income from your desired annual retirement income. The remaining “income gap” is what your personal savings must fund. Social Security is assumed to begin at your specified retirement age and to be inflation-adjusted by the Social Security Administration.

The real rate of return is your investment return after adjusting for inflation, calculated using the Fisher equation: Real Return = (1 + Nominal Return) / (1 + Inflation Rate) − 1. For example, a 7% nominal return with 3% inflation gives a real return of about 3.88%. The calculator uses the real return to size your nest egg in today's purchasing power, ensuring your retirement income maintains its real value.

The On Track badge indicates whether your current savings trajectory meets your retirement target. “On Track” means your projected savings equal or exceed your target (surplus ≥ 0). “Close” means you are within 10% of your target. “Behind” means a 10–30% shortfall. “Far Behind” means a shortfall exceeding 30% of your target.

If your projected savings exceed the inflation-adjusted retirement target, you have a surplus and are on track. You may be able to retire earlier, reduce contributions, or plan for a higher retirement income. The calculator shows the exact surplus amount. However, actual market returns will vary, so a surplus provides a valuable safety margin.
Disclaimer

This calculator is for educational purposes only and assumes constant returns, contributions, and inflation. Actual retirement outcomes depend on market performance, tax treatment, health costs, and many other variables. This tool should not be used as the sole basis for retirement planning decisions. Consult a certified financial planner for personalized advice.

Related Calculators

Professional finance illustration representing 50/30/20 Budget Planner Calculator

50/30/20 Budget Planner Calculator

Plan your monthly budget with the 50/30/20 rule. Enter your income and spending to see...

Try Calculator →
Professional finance illustration representing Monte Carlo Retirement Calculator

Monte Carlo Retirement Calculator

Monte Carlo retirement simulation calculator.

Try Calculator →
Professional finance illustration representing TVM Calculator

TVM Calculator

Solve any time value of money problem: present value, future value, payment, interest rate, or...

Try Calculator →