This 401k calculator projects a future balance from your current account value, salary, employee contribution percent, employer match percent of salary, annual return, and years. Monthly deposits equal salary × (contrib% + match%) ÷ 100 ÷ 12, then compound with the starting balance.
Workers use it to see how deferral and match choices change long range outcomes. For general compounding without salary fields, try the compound interest calculator. For required withdrawals later in life, see the RMD tools on Multicalify including the inherited IRA RMD calculator when beneficiaries are involved.
How the formula works
Combined annual contribution rate is employee percent plus match percent of salary. Divide that dollar amount by 12 for a monthly deposit. Future value compounds the current balance and those deposits monthly at the stated annual return.
Worked example
Balance $25,000, salary $70,000, employee 6 percent, match 3 percent, return 7 percent, 25 years. Monthly deposit = 70,000 × 0.09 ÷ 12 = $525. Projected balance ≈ $568,423.09.
| Input | Value |
|---|---|
| Current balance | $25,000 |
| Annual salary | $70,000 |
| Employee contribution | 6% |
| Employer match of salary | 3% |
| Annual return | 7% |
| Years | 25 |
| Projected balance | ~$568,423.09 |
How to use the fields
- Current balance is today’s 401(k) value.
- Annual salary drives contribution dollars.
- Employee contribution is your deferral percent of salary.
- Employer match is modeled as a percent of salary in this form.
- Annual return and years set growth assumptions.
Capture the match
If your plan matches contributions, leaving free match dollars on the table is costly. Raise deferrals at least to the effective match when cash flow allows, then model the higher combined percent here.
Salary growth
The default model keeps salary flat. If you expect raises, either raise the salary input in a second scenario or accept that the projection is conservative on contribution dollars.
Common mistakes
- Entering a match formula incorrectly as a flat salary percent
- Ignoring plan fees in the return assumption
- Counting years after you plan to stop working contributions
- Treating the projection as a guaranteed pension
Contribution checklist
- Read the employer match summary in the plan SPD.
- Convert that rule into an effective match percent of salary for this tool.
- Pick base and cautious return rates.
- Increase deferrals when bonuses or raises arrive.
Taxes and withdrawals
Traditional 401(k) growth is tax deferred, not tax free forever. Roth options change when tax is paid. This calculator reports a pretax style balance projection without tax haircuts.
Annual limits and true ups
IRS elective deferral limits can cap how large the contribution percent can be on a high salary. If your percent times salary exceeds the limit, lower the modeled contrib percent. Some plans true up match at year end; this monthly model spreads match evenly and may not match payroll timing.
After tax and Roth 401(k) sources change tax treatment, not the compounding arithmetic on the balance field.
Loan and hardship leakage
Plan loans reduce invested balance and can pause contributions. If you take a loan, lower the principal input to the remaining invested amount and adjust contribution assumptions. Hardship withdrawals have separate rules and possible taxes.
Keep an emergency fund outside the plan so you are less likely to raid retirement money.
Target date funds and glide paths
A single return rate should reflect the fund mix you actually hold. Target date funds lower equity share over time, so a constant 7 percent for 25 years may be optimistic. Run a second case at a lower rate for the later decade.
Revisit beneficiaries and contribution percents after life events. The projection is only as current as the last inputs you typed.
Roth versus traditional deferrals
Roth 401(k) deferrals do not change the compounding math on the balance you enter, but they change take home pay today and tax treatment later. If switching to Roth reduces what you can contribute in dollars, lower the contribution percent to what cash flow allows and rerun the projection.
Employer match is often deposited as pretax even when your deferrals are Roth. Read the plan notice so you model taxes correctly outside this tool.
Limitations
Results omit IRS contribution caps, true up match timing, loans, and hardship rules. They are planning estimates. Confirm deferral elections and match deposits on your plan statements, and stress test with a lower return case before you set spending goals.