401(k) Calculator. Model a 401(k) balance from current savings, annual employee and employer contributions, a whole-year horizon, and an entered net-return scenario.
A quick decision brief for this specific tool
Current 401(k) balance, annual employee contribution, annual employer contribution taken from current plan/payroll evidence, whole-year horizon, and a constant annual net-return scenario
Starting balance, employee and employer deposits, total deposits, modeled growth, and modeled final balance
Nominal annual net return divided by 12 with equal month-end deposits; employer contributions are entered directly rather than inferred from a generic match formula
Choose your path
Model one bounded 401(k) contribution-growth scenario from current plan and payroll evidence without inventing an employer match or promising a return.
See how current balance and known contributions combine over time.
Enter current balance plus annual employee and employer dollar amounts, then inspect deposits versus modeled growth.
Can reproduce the scenario and knows the tool did not infer plan eligibility or a match.
Separate employer deposits from employee deposits and vesting rights.
Use a current plan/payroll estimate for employer contributions and review the DOL plan/vesting source.
Does not treat modeled employer deposits as guaranteed or fully vested.
Stress a short horizon without a retirement-readiness verdict.
Enter a bounded horizon and net-return scenario, compare one assumption at a time, and review taxes/fees/withdrawal omissions.
Treats final balance as deterministic arithmetic rather than a forecast or action recommendation.
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
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Annual employee and employer inputs are each divided by 12 and deposited at the end of every modeled month.
Monthly Deposit = (Annual Employee + Annual Employer Contribution) ÷ 12The current balance compounds monthly at the entered nominal net-return scenario, and each month-end deposit receives only its remaining periods of modeled growth.
FV = Balance × (1+r)^n + Monthly Deposit × [(1+r)^n − 1] ÷ rStarting balance and both deposit sources remain separate from modeled growth so the final figure can be audited.
Modeled Growth = Final Balance − Starting Balance − Employee Deposits − Employer DepositsUpdated: August 2026
Use current balance plus employee and employer annual dollar amounts from plan or payroll evidence.
→ Starting balance, both deposit sources, and modeled growth reconcile to the final balance.
Model a plan or eligibility period with no known employer deposit without inventing a match.
→ Employer deposits remain $0 while employee deposits and modeled growth stay explicit.
Remove modeled growth to check contribution arithmetic directly.
→ Final balance equals starting balance plus employee and employer deposits; modeled growth is $0.
This calculator separates current balance, employee deposits, employer deposits, and modeled growth. Enter the employer dollar amount from current plan or payroll evidence; the tool does not invent a match formula. The constant net return is a smooth scenario, not a forecast or retirement-readiness verdict.