Quick Summary
When can I retire? A free calculator plus the four-input rule of thumb that gets you within 2 years of the right answer. Includes worked examples at 30, 45, and 55.
Quick answer. A retirement age calculator takes four inputs: current age, current invested balance, annual savings, and target retirement spending. The output: the year you can retire if your assumptions hold. Our free Simple Retirement Calculator runs the math in browser with no signup. The rule of thumb: divide 25 times your annual spending minus current balance by your annual savings, then add years until you hit the target via 7 percent compound growth.
The “when can I retire” question feels intimidating because most calculators ask for 25 inputs. The honest version of the calculation needs four. This post walks through both the simple version and the longer version, with three worked examples at different ages.
The four inputs that matter most
If you can answer these four questions, you can produce a retirement age estimate within 2 years of the more sophisticated versions.
- Current age.
- Current invested balance. Sum across all accounts (401k, IRAs, taxable brokerage, etc.).
- Annual savings. What you add to invested accounts each year (your contributions plus employer match).
- Target retirement spending. What you’d want to spend per year in retirement, in today’s dollars.
That’s it. Everything else (Social Security, pension, healthcare, taxes) refines the answer; the four-input model gets you the headline number.
The simple formula
Retirement balance needed = Target spending x 25
Current shortfall = Retirement balance needed - Current balance
Years to close shortfall = Years where (Annual savings + previous balance compounded) reaches targetIn plain English: figure out your target portfolio (25x annual spending), then project forward year by year adding savings and compounding the balance until you hit the target. The year you hit it is the year you can retire.
Math behind the projection (per year):
End balance year n = (Beginning balance year n + Annual savings) x (1 + Real return rate)7 percent real return is the common assumption. Lower (5 percent) for conservative; higher (8 percent) is optimistic.
A worked example: age 30
Anjali is 30. Currently has $80,000 invested. Saves $25,000/year (her contributions plus employer match). Target retirement spending: $55,000/year.
Target portfolio (25x): $55,000 x 25 = $1,375,000
Current shortfall: $1,375,000 - $80,000 = $1,295,000
Year-by-year projection at 7 percent real return:
| Age | Beginning balance | Savings | End balance |
|---|---|---|---|
| 30 | 80,000 | 25,000 | 112,350 |
| 35 | 252,000 | 25,000 | 296,990 |
| 40 | 519,000 | 25,000 | 582,330 |
| 45 | 916,000 | 25,000 | 1,007,370 |
| 50 | 1,470,000 | 25,000 | 1,599,650 |
| 52 | 1,375,000 hit |
Anjali hits her target around age 52. At 7 percent real return, she could retire at 52.
A worked example: age 45
Marcus is 45. Currently has $320,000 invested. Saves $35,000/year. Target retirement spending: $70,000/year.
Target portfolio (25x): $70,000 x 25 = $1,750,000
Current shortfall: $1,750,000 - $320,000 = $1,430,000
Year-by-year projection at 7 percent real return:
| Age | Beginning balance | Savings | End balance |
|---|---|---|---|
| 45 | 320,000 | 35,000 | 379,950 |
| 50 | 706,000 | 35,000 | 793,720 |
| 55 | 1,242,000 | 35,000 | 1,366,890 |
| 60 | 1,956,000 | 35,000 | 2,131,170 |
| 57-58 | 1,750,000 hit |
Marcus hits his target around age 57-58. At 7 percent real, he could retire then.
A worked example: age 55
Linda is 55. Currently has $710,000 invested. Saves $20,000/year (smaller because retirement is closer). Target retirement spending: $60,000/year.
Target portfolio (25x): $60,000 x 25 = $1,500,000
Current shortfall: $1,500,000 - $710,000 = $790,000
Year-by-year projection at 6 percent real return (Linda is more conservative; closer to retirement, less time to recover from down markets):
| Age | Beginning balance | Savings | End balance |
|---|---|---|---|
| 55 | 710,000 | 20,000 | 773,800 |
| 60 | 1,030,000 | 20,000 | 1,113,000 |
| 63 | 1,500,000 hit |
Linda hits her target around 63. With Social Security joining at 67, the early-retirement gap from 63 to 67 is the planning question; the portfolio supports it but with less margin than a younger retiree.
What the simple version misses
Honest limitations.
Social Security and pensions. Adding $20K to $30K of inflation-adjusted income at 67 (or whenever you claim) materially changes the picture. The simple model treats portfolio withdrawal as the only income source.
Healthcare bridge. US retirees under 65 pay for healthcare without Medicare. ACA marketplace plans cost $500 to $2,000+ a month depending on income, age, and state. The simple model rolls this into “target spending” but it’s worth modeling explicitly if you’re early-retiring.
Tax efficiency in withdrawal. Drawing from taxable, tax-deferred, and Roth in different orders affects how long the portfolio lasts. The simple model ignores this; the full retirement projection template handles it.
Sequence-of-returns risk. A bad first decade is much worse than a bad last decade. Deterministic models smooth this away. Monte Carlo (in tools like ProjectionLab) captures it.
One-time events. Inheritances, home sales, college costs, healthcare events. Add or subtract from the projected balance in the year they happen.
For an order-of-magnitude answer, the simple model is fine. For a real plan, layer in Social Security at minimum.
Adding Social Security to the simple model
Two changes:
- Estimate your Social Security benefit at full retirement age (67). The Social Security Administration provides this on your statement at ssa.gov/myaccount. Roughly $2,000 to $3,500 per month for most middle-income workers, more for higher earners.
- Subtract that annual benefit from your target retirement spending starting at the claim year.
Example for Marcus (above): Social Security estimated $2,400/month at 67 = $28,800/year. From 67 onward, his portfolio only needs to cover $70,000 - $28,800 = $41,200/year. The portfolio drawdown rate effectively drops, extending sustainability.
In the projection, this means his $1,750,000 target at 25x is conservative; the realistic target accounting for Social Security is closer to $1,200,000. He could retire 2 to 3 years earlier than the simple model suggests.
Where the calculator lives
The free Simple Retirement Calculator takes the four inputs above and runs the projection in browser. No signup, no email gate. The output is your projected retirement age and a year-by-year balance chart.
For a fully built retirement plan with multiple accounts, withdrawal phase modeling, Social Security and pensions, see the paid Retirement Financial Planning Projections template ($49). It handles everything the simple model glosses over.
Sensitivity to the four inputs
How much each input moves the answer.
Current age: Each year you start later moves retirement age by roughly 0.7 to 1 year (you have less compounding time). Massive lever for late starters; not in your control going forward.
Current balance: Each $50,000 of additional starting balance moves retirement age earlier by roughly 1 year for someone in their 30s, 0.7 years for someone in their 40s.
Annual savings: Each additional $5,000 saved per year moves retirement age earlier by roughly 0.5 to 1 year. The biggest variable in your control.
Target spending: Each $5,000 reduction in target spending moves retirement age earlier by 1 to 1.5 years. The other big lever.
The two levers in your control (savings rate and target spending) move the answer most. Most people focus on increasing income; reducing target spending is just as effective and often easier.
Get the template
- Simple Retirement Calculator — Four-input retirement age estimate. Free, no signup.
- Retirement Financial Planning Projections — 40-year accumulation and withdrawal projection with configurable assumptions.
- Retirement Financial Planning Projections — 40-year accumulation and withdrawal projection with configurable assumptions.