403(b) Calculator — retirement plan growth

How it works

A 403(b) is a tax-deferred retirement plan for employees of public schools, churches and certain nonprofits — the counterpart to a 401(k) in the private sector. Its growth is the same compound-interest math, in two pieces (per LibreTexts):

• The current balance grows to B × (1 + r)ᵗ over t years at return r.
• Each annual contribution compounds from when it is made, so the stream of deposits grows to d × ((1 + r)ᵗ − 1) ÷ r — the future value of an annuity.

Adding the two gives the projected balance at retirement. The calculator also splits the result into total paid in (your starting balance plus every contribution) and investment growth (everything above that), which shows how compounding does the heavy lifting over a long horizon.

The return is an assumption, not a guarantee — markets vary year to year. Contributions are also capped by an annual IRS limit, and many employers match part of what you put in; enter your total expected annual contribution to include any match.

Worked example

Starting with $10,000, adding $12,000 a year, at a 7% return for 30 years: the balance grows to about $76,000 and the contributions grow to about $1,133,500, for a projected $1,209,651.99. Of that, $370,000.00 was paid in ($10,000 starting balance + $12,000 × 30 in contributions) and the remaining ~$840,000 is investment growth.

Frequently asked questions

How much will my 403(b) be worth?

Grow your current balance and your yearly contributions at your expected return and add them. For $10,000 plus $12,000 a year at 7% over 30 years, that is about $1.21 million.

What is a 403(b)?

It is a tax-deferred retirement savings plan for employees of public schools, nonprofits and some religious organizations. It works much like a 401(k): contributions are pre-tax and grow untaxed until withdrawal.

How is a 403(b) different from a 401(k)?

Mainly who offers it — 403(b) plans are for public-education and nonprofit employees, 401(k)s for private-sector workers. The contribution limits and tax treatment are very similar, and the growth math is identical.

Should I include my employer's match?

Yes — a match is extra money that compounds just like your own contributions. Add it to your annual contribution figure so the projection reflects the full amount going in each year.

Does the calculator account for contribution limits?

No. It projects whatever contribution you enter. The IRS sets an annual limit (with extra catch-up room after age 50), so keep your contribution within the current limit for a realistic plan.

Why is so much of the balance "growth"?

Because compounding pays returns on prior returns. Over decades, the growth on early contributions dwarfs the contributions themselves — which is why starting early matters so much.