What a 403(b) grows into
A 403(b) is the retirement plan for teachers, hospital staff, university employees and non-profit workers — the public-sector and charitable cousin of the 401(k). Contributions come out of salary before tax, grow untaxed, and are taxed on withdrawal. This calculator projects the balance from a monthly contribution, a return and a horizon.
The formula
Worked example: $600 a month at 7% for 30 years
- Contributed: $216,000
- Balance at retirement: $731,983
- Growth: $515,983 — 70% of the final figure never came out of a paycheque
The 2025 limits
| Who | Elective limit | Per month |
|---|---|---|
| Under 50 | $23,500 | $1,958 |
| 50 and over (catch-up +$7,500) | $31,000 | $2,583 |
| Ages 60–63 (SECURE 2.0 super catch-up +$11,250) | $34,750 | $2,896 |
| 15+ years with the same employer | up to +$3,000 a year, $15,000 lifetime |
The 15-year rule is unique to 403(b) plans and lets long-serving employees who contributed little in earlier years make it up. The $600 in the example uses less than a third of the basic limit.
What changes the outcome
| Monthly | Return | Years | Balance |
|---|---|---|---|
| $600 | 7% | 30 | $731,983 |
| $600 | 7% | 20 | $312,556 |
| $1,000 | 7% | 30 | $1,219,971 |
| $600 | 5% | 30 | $499,355 |
Ten fewer years cost 57% of the balance. Two points of return cost 32%. The return in a 403(b) depends heavily on the plan's investment menu: many older plans offer only annuity products with fees of 1.5% to 2.5%, which turns a 7% market return into 5% and the $731,983 into $499,355. Checking the expense ratios is worth more than any contribution increase.
Roth 403(b)
Most plans now offer a Roth option: contributions are taxed today, withdrawals are tax-free. On the example, paying tax on $216,000 of contributions now buys tax-free access to $731,983 later. The Roth wins for anyone who expects a higher tax rate in retirement than today, which for early-career employees is usual.
What this calculator leaves out
Employer matching, which is less common in 403(b) plans than in 401(k)s but where offered is free money; plan fees; the tax on withdrawal; and the 10% penalty on withdrawals before 59½, with an exception for those who leave the employer at 55 or later.
Related calculators
- 401(k) calculator — the private-sector equivalent
- Roth IRA calculator — the after-tax alternative alongside it
- Retirement calculator — whether the balance is enough