How this calculator works
This US 401(k) estimate adds employee deferrals and a plan-based employer match to a balance that compounds once each year: $50,000 becomes $1,728,711 under the defaults.
- Step 1Set the US account$50,000 in USDthe opening balance and salary
- Step 2Add annual deposits10% employee deferralplus the match you enter
- Step 3Apply yearly growth7% assumed returnthen add deposits at year-end
For each year, employee contributions are the lower of salary times your contribution rate or the annual limit. The match applies to eligible deferrals up to the salary percentage you enter.
Timing and limits
- Year-end depositsThe opening balance earns a full year of assumed return before that year’s employee and employer deposits are added.
- Plan-specific matchThe match rate and salary cap are your inputs. Real plans can use different formulas, timing and vesting rules.
- Nominal dollarsTaxes, fees, withdrawals, inflation, other employer contributions and aggregate plan limits are outside this estimate.
- Constant assumptionsThe annual return and salary-growth rates stay the same each year; neither is a forecast.
The default employee limit is $24,500, the IRS 2026 elective-deferral limit for most participants under age 50. It remains fixed in every modeled year, so change it if you need a different scenario or applicable limit.
Worked example
- Employee deposit
Eₜ = min(salaryₜ × employee rate, annual employee limit)- Employer match
Mₜ = min(Eₜ, salaryₜ × match salary limit) × match rate- Year-end balance
Bₜ = Bₜ₋₁ × (1 + annual return) + Eₜ + Mₜ
- B₀starting account balance $50,000
- salary₁first modeled year salary $80,000
- E₁ + M₁first year employee and employer deposits $10,400
- Starting balance$50,000
- Employee and employer deposits10% employee rate plus 50% match up to 6% of salary$494,784
- Apply annual growth7% assumed return for 30 annual periods$1,183,926
- Projected balance$1,728,711
The default projection assumes a $50,000 opening account, $80,000 salary, 10% employee contribution, a 50% match on eligible contributions up to 6% of salary, 7% annual return, 3% salary growth, and 30 years. The values come from the calculator’s tested logic.
Reading the estimate
- 7% return$1,728,711The default scenario over 30 years.
- 4% return$1,010,950Same contributions and salary growth, lower assumed return.
- Employee deposits
- Employer match
- Investment gain
The result is a nominal account-value illustration before taxes and fees. It does not show what you could withdraw or spend after plan rules, taxes or inflation.
Other US retirement accounts
A 401(k) is one of several US retirement accounts, and each has its own limits and tax treatment.
For an individual account funded after tax, the Roth IRA calculator checks the yearly contribution limit and projects growth. Once withdrawals are required, the RMD calculator works out the minimum from the IRS life-expectancy table.
Planning retirement in India instead? The retirement planner works in rupees, with inflation-linked expenses.
Common mistakes
Mistake: Treating the default $24,500 limit as a future IRS limit.
Instead: It is the verified 2026 limit for most participants under 50; edit it for another year or applicable circumstance.
Mistake: Assuming every employer uses the entered match formula.
Instead: Check your plan’s matching schedule, eligible pay, vesting and true-up provisions.
Mistake: Reading the balance as a prediction or take-home amount.
Instead: Compare assumptions and account for market risk, tax, fees and inflation separately.
This US-only calculator is for education, not investment, tax or legal advice. It does not recommend a contribution rate or an investment. Review your employer plan documents and ask a qualified professional about personal decisions.
Checking the method
A separate script recomputes every test case two ways: year by year, and as a sum of each year's deposits grown to the end.
Read how we test our calculators, or browse more money calculators.