Retirement Shortfall Calculator
Compare the nest egg you'll need against what your current savings and contributions are projected to grow to, and see any retirement shortfall.
How to use this tool
- Enter your expected annual spending in retirement (today's dollars).
- Set a safe withdrawal rate to derive the nest egg you'll need.
- Enter your current savings, annual contributions, return, and years to retirement.
- Read your projected balance and whether you face a shortfall or a surplus.
Are you saving enough to retire? This calculator compares the nest egg you'll need against what your savings are projected to grow to, and shows any shortfall.
Formula
Nest egg needed = Annual spending ÷ (Withdrawal rate ÷ 100) — the inverse of the safe-withdrawal rate (25× spending at 4%).
Projected savings = Current × (1 + r)n + Annual contributions × [(1 + r)n − 1] ÷ r, combining the growth of today's balance with the future value of ongoing contributions (r = 0 gives Current + Contributions × n).
Shortfall = Needed − Projected. A positive number is a gap to close; a negative number means you are on track with a surplus.
How it works
A retirement shortfall is the gap between the nest egg your future spending requires and what your savings are on pace to become. This calculator computes both sides: the target from the safe-withdrawal rule (annual spending divided by your withdrawal rate) and the projection from compounding today's balance plus your ongoing contributions forward to retirement.
The projection uses the future-value-of-an-annuity formula for contributions and straightforward compound growth for the existing balance, both at a single assumed return. A negative shortfall means a surplus — your trajectory clears the target — while a positive shortfall is the dollar gap you would need to close by saving more, working longer, spending less, or earning a higher return.
Everything is in today's dollars, so use a real (after-inflation) return and express spending in current terms to keep both sides consistent. The model assumes level contributions and a constant return, and ignores Social Security, pensions, taxes, and sequence-of-returns risk. Reviewed by the AbraCalc Retirement Desk against standard retirement-planning formulas. This calculator provides general information, not financial advice; consult a qualified professional for decisions about your own situation.
Worked example
$40k spending, 4% rule, $100k saved, $10k/yr, 7% for 30 years
- Nest egg needed = $40,000 ÷ 0.04 = $1,000,000.
- Growth factor g = (1.07)30 = 7.612255.
- Current grows to $100,000 × 7.612255 = $761,225.50.
- Contributions grow to $10,000 × (7.612255 − 1) ÷ 0.07 = $944,607.86.
- Projected savings = $761,225.50 + $944,607.86 = $1,705,833.37.
- Shortfall = $1,000,000 − $1,705,833.37 = −$705,833.37 (a surplus).
Projected shortfall: −$705,833.37 — needing $1,000,000 against $1,705,833.37 projected, you are on track.
Nest egg needed by annual spending and withdrawal rate
| Annual spending | 3% rule | 4% rule | 5% rule |
|---|---|---|---|
| $30,000 | $1,000,000 | $750,000 | $600,000 |
| $40,000 | $1,333,333 | $1,000,000 | $800,000 |
| $50,000 | $1,666,667 | $1,250,000 | $1,000,000 |
| $60,000 | $2,000,000 | $1,500,000 | $1,200,000 |
| $80,000 | $2,666,667 | $2,000,000 | $1,600,000 |
Key terms
- Retirement shortfall
- The gap between the savings your retirement spending requires and what you are projected to accumulate.
- Nest egg
- The total portfolio you need at retirement to fund your spending at your chosen withdrawal rate.
- Safe withdrawal rate
- The share of your portfolio you can draw each year with a high chance of not running out; 4% is the common benchmark.
- Real return
- Investment return after inflation; using it keeps spending and savings on the same today's-dollars footing.
Frequently asked questions
- How is a retirement shortfall calculated?
- Subtract your projected savings at retirement from the nest egg your spending requires. The target is annual spending divided by your withdrawal rate; the projection compounds your current balance and contributions forward.
- What does a negative shortfall mean?
- A negative shortfall is a surplus — your projected savings exceed what you need. You are on track and have a cushion against weaker-than-expected returns.
- Should I use a real or nominal return?
- Use a real, after-inflation return and express spending in today's dollars. That keeps both sides of the comparison consistent without separately modeling inflation.
- Does this include Social Security?
- No. It only counts your invested savings. If you expect Social Security or a pension, reduce your required spending by that income before entering it, or treat the result as conservative.