How this calculator works
A 403(b) is a US retirement plan offered by public schools, hospitals, churches and other tax-exempt employers. Employees contribute through salary deferral, the money grows without tax until withdrawal, and many employers add a match. This calculator projects the balance at retirement from the current balance, the contribution percentage of salary, a salary increase each year and an investment return. Contributions are assumed to be made at the end of each year and to grow with salary, so each year's contribution is larger than the last. In contribution mode the calculator works back from a target balance and retirement age to the percentage of salary needed. In years mode it finds how long a given percentage takes to reach the target. The model does not include employer matches, catch-up contributions, fees, fund expense ratios or any tax on withdrawal. For 2026 the IRS elective deferral limit is $24,500, with a $8,000 catch-up for those aged 50 and over and a $11,250 catch-up for ages 60 to 63. Those caps are per employer and not modelled here: at a high salary the percentage you can actually defer may be lower than the model assumes. Canadian readers: the closest equivalents are an RRSP or a registered pension plan, which have different contribution limits and tax treatment.
Formula
Let r be the annual return, g the salary growth, S the salary, c the contribution rate, B the starting balance and n the years. Balance = B(1+r)^n + cS[(1+r)^n - (1+g)^n]/(r-g), with n(1+r)^(n-1) used for the salary factor when r = g. Contribution rate needed = (target - B(1+r)^n)(r-g) / (S[(1+r)^n - (1+g)^n]). Years to a target are found numerically. Total contributed = B + cS[(1+g)^n - 1]/g, and growth = balance - contributions.
Worked example
A $25,000 balance, $70,000 salary, 8% contribution, 7% return, 3% salary growth and 30 years give $916,205.34. The first-year contribution is $5,600, total contributions including the starting balance are $291,422.33 and investment growth is $624,783.01. To reach $1,000,000 in 30 years, the required contribution rate is about 8.92% of salary.
Advertisement
Frequently asked questions
Does the calculator include an employer match?
No. A match is extra money and raises the final balance. Add the match percentage to your own contribution rate if the employer matches dollar for dollar, or model the match separately if it has a cap.
What are the 2026 contribution limits?
The elective deferral limit is $24,500, with an $8,000 catch-up at age 50 and over and an $11,250 catch-up for ages 60 to 63. The total annual additions limit, including employer contributions, is $72,000. Check the IRS notice for the current year before relying on these figures.
Is a 403(b) the same as a 401(k)?
They are similar: both are employer-sponsored salary-deferral plans with the same elective deferral limits. A 403(b) is for employees of tax-exempt organisations and public schools, and it may offer annuities as well as mutual funds.
Should I use the return before or after fees?
After fees. Fund expense ratios and any plan administration charge reduce your return. A 0.5% fee on a 7% return leaves 6.5%, and over 30 years the difference is substantial.
What is the Canadian equivalent?
A Registered Retirement Savings Plan (RRSP) or a registered pension plan. Contributions to an RRSP are deductible within limits and withdrawals are taxed as income, which is different from the US Roth and traditional split.