How the 457(b) Calculator Works
What each field means, how the math works, and what the results actually tell you.
The inputs
Plan type
The calculator asks you to specify whether you have a governmental or non-governmental 457(b). This doesn't affect the projection math at all. It affects the warnings shown in your results.
Governmental plans are offered by state and local governments. Assets are held in a trust separate from your employer, can be rolled to an IRA when you leave, and carry no creditor risk. Non-governmental plans are offered by certain tax-exempt organizations, primarily hospitals and large nonprofits. Assets remain on the employer's books until distributed, cannot be rolled to an IRA, and are technically at risk from employer creditors. Select the type that matches your employer so the results show the right risk information.
Current 457(b) balance
Your account balance today, before this year's contributions. Check your most recent statement or your plan provider's online portal. If you have multiple deferred compensation accounts from prior employers, you can run separate projections or add them together depending on whether you'll be consolidating them.
Even a modest existing balance has a meaningful compounding effect. A $30,000 balance growing at 6.5% for 20 years becomes roughly $107,000 without adding another dollar. That's nearly $77,000 in growth on money already saved.
Annual contribution
The total dollar amount you contribute per year. The 2026 IRS limit for 457(b) employee elective deferrals is $23,500. If the 3-year special catch-up is active, the calculator locks this to $23,500 and doubles your effective limit automatically.
Enter the actual dollar amount you contribute, not a percentage. If you contribute 8% of a $75,000 salary, enter $6,000. If you're at or near the limit, the calculator validates against the $23,500 cap (or $47,000 with the special catch-up active) and shows an error if you exceed it.
Employer contribution
An optional toggle. Employer contributions to 457(b) plans are less common than in 401(k) or 403(b) plans, but some governmental plans include them. Toggle it on and enter the flat dollar amount your employer contributes per year. The results will show you the compounded value of that employer money and compare your projected balance with and without it.
Even a modest employer contribution has an outsized long-run impact because it compounds alongside your own contributions for the entire projection period.
Years until retirement
How many full years you plan to keep contributing before separating from your employer. The calculator applies contributions for exactly this many years using the standard future value formula, then stops.
One nuance specific to 457(b) plans: you don't have to retire to access the money penalty-free. You just have to separate from service. Some people use a 457(b) aggressively because they plan to leave public sector work at 50 or 55, well before traditional retirement age. Enter the number of years you'll stay with this employer, not necessarily when you'll stop working entirely.
Expected annual return
The assumed annual rate of return on your investments, between 3% and 10%. The default is 6.5%, which sits between a conservative bond-heavy allocation (roughly 4-5% historical real return) and an equity-heavy portfolio (roughly 7-8% inflation-adjusted long-run average).
This is the most sensitive variable in any long-term projection. The difference between 5% and 7% over 25 years on a $500,000 account is roughly $500,000 in ending balance. If your 457(b) is invested primarily in a stable value fund or short-term bond fund, 3-4% is more realistic. If it's in a diversified stock index fund, 6-7% is a reasonable working assumption. Adjust based on your actual allocation.
Age 50+ catch-up
Adds $7,500 to your annual contribution total, bringing the employee limit from $23,500 to $31,000. Available once you reach age 50. Cannot be combined with the 3-year special catch-up in the same year. If you toggle both, the calculator shows an error and asks you to choose one.
3-year special catch-up
A provision unique to 457(b) plans. In the three calendar years before your plan's normal retirement age, you can contribute up to double the standard annual limit if you have unused contribution room from prior years when you contributed below the maximum.
When this toggle is active, the calculator sets your annual employee contribution to $23,500 and adds another $23,500 on top, for a total of $47,000 per year. This is the maximum allowed. Your actual available amount may be lower depending on how much unused room you've accumulated. Confirm with your plan administrator before assuming you can use the full $47,000.
The special catch-up cannot be combined with the age 50+ catch-up. Selecting the special catch-up automatically disables the age 50+ toggle in the calculator.
The outputs
Projected balance at retirement
The future value of your 457(b) after the number of years you specified, using the standard compound growth formula:
Where PV is your current balance, r is the annual return rate as a decimal, n is years until retirement, and PMT is your total annual contributions including any employer contribution and catch-up amounts. Contributions are assumed to be made once per year at the start of each period.
No-penalty withdrawal notice
The green callout in your results reminds you that the projected balance is accessible without penalty at any age after separating from your employer. This isn't a projection output, it's a reminder about the plan's most important structural feature. A 401(k) with the same projected balance would cost you 10% of every dollar you withdrew before age 59.5.
On a $500,000 balance, that's a $50,000 penalty you don't owe with a 457(b). The actual dollar advantage depends on how much you withdraw early and at what tax bracket.
Monthly income (4% rule)
Your projected balance multiplied by 4%, then divided by 12. The 4% rule originated in the 1998 Trinity Study by three finance professors who analyzed how much a retiree could withdraw annually without running out of money over a 30-year retirement, tested against historical market returns going back to the Great Depression.
4% is a benchmark, not a guarantee. If you retire early at 52 and expect a 40-year retirement, some planners use 3.5% to be safer. If you have substantial other income from a pension or Social Security, 4.5% or higher may be reasonable. The calculator uses 4% as the widely understood starting point.
Contributions vs. growth breakdown
The stacked bar splits your projected balance into money you put in (including employer contributions and your starting balance) and money the market generated. Over long time horizons, growth dominates. At 6.5% for 25 years, a single dollar invested today grows to roughly $4.83, meaning about 79% of the ending value comes from growth rather than contributions.
This is why the early years of saving matter disproportionately. A dollar contributed at age 30 has 35 years to compound. The same dollar at age 50 has 15. Both dollar amounts are identical at contribution time. At retirement they're vastly different.
Governmental dual-limit notice
For governmental plan holders, the results show a reminder that the 457(b) limit is completely separate from any 403(b) or 401(k) you also participate in. This callout only appears for governmental plans because non-governmental 457(b) plans don't share the same rollover flexibility and the dual-contribution strategy is less compelling given the creditor risk.
Non-governmental creditor risk warning
For non-governmental plan holders, the results show a yellow warning noting that the projected balance remains on your employer's books until distributed. This is factual information about the plan type you selected, not a projection output. It doesn't change the math. It changes how you should think about the risk profile of that balance relative to a governmental plan or an IRA.
Frequently asked questions
Does this calculator account for inflation?
No. All figures are in nominal dollars. A projected balance of $900,000 in 20 years will buy less than $900,000 buys today. To get a rough inflation-adjusted estimate, reduce the return rate by your expected inflation assumption. At 6.5% nominal returns and 2.5% inflation, entering 4% gives you a projection roughly in today's purchasing power.
Does the calculator model the no-penalty advantage in dollar terms?
Not directly. The calculator shows your projected balance and notes that it's accessible without penalty. To quantify the penalty savings in dollar terms, multiply any amount you plan to withdraw before age 59.5 by 10%. That's the amount a 401(k) or 403(b) holder would owe that you don't. On $200,000 in early withdrawals, that's $20,000 you keep.
What if I contribute to both a 457(b) and a 403(b)?
Run each calculator separately, then add the projected balances. The limits are independent, so the calculations are independent. The 457(b) calculator handles 457(b) contributions; the 403(b) calculator handles 403(b) contributions. Your total retirement picture is the sum of both projections plus any pension, IRA, or other savings.
Why does the 3-year catch-up apply for every year in the projection?
The calculator doesn't know when your normal retirement age is or how many years of unused contribution room you've accumulated. When you activate the special catch-up toggle, it applies the doubled limit for the entire projection period you specified. If you're only eligible for two more years of the catch-up, set your years to 2 and run a separate projection for the years after with the standard limit.
Can I use this for a Roth 457(b)?
The projection math is identical whether your contributions go into a traditional pre-tax 457(b) or a Roth 457(b). The difference is when you pay taxes: pre-tax now with taxable withdrawals later, or after-tax now with tax-free withdrawals later. This calculator doesn't model the tax impact of either choice. For a Roth vs. traditional comparison based on your specific tax situation, a fee-only financial advisor can model both scenarios.