How the projection works
For every year until retirement the calculator takes your salary, works out your contribution and the employer match, caps your contribution at the IRS limit for your age, and grows the balance by your assumed return. Your salary then rises by your growth rate and the process repeats. Contributions are assumed to arrive through the year, so they earn about half a year of growth in the year they are made.
The formulas, and what every variable means
your contribution = the smaller of: salary × contribution %, or the IRS limit
employer match = the smaller of (your contribution, salary × match limit %) × match %
new balance = old balance × (1 + g) + (your contribution + match) × (1 + g ÷ 2)
next year's salary = salary × (1 + salary growth)
| Term | Meaning |
|---|---|
| Contribution % | The share of your salary you put in |
| IRS limit | The most you may contribute in a year, which depends on your age (see below) |
| Match % | How much of each of your dollars the employer matches. 50 means 50 cents per dollar. |
| Match limit % | The salary percentage up to which the employer will match |
| g | Assumed annual investment return |
| (1 + g ÷ 2) | Contributions arrive through the year, so on average they earn half a year of growth |
| Today's dollars | Final balance ÷ (1 + inflation)years, a way to judge buying power |
Worked example 1: the default plan, with year one by hand
Age 30, retiring at 65, a $75,000 salary growing 3% a year, saving 8% with a 50% match up to 6% of pay, $10,000 already saved and a 7% return.
- Your contribution: $75,000 × 8% = $6,000 (under the IRS limit).
- Matchable amount: the smaller of $6,000 and 6% × $75,000 = $4,500.
- Employer match: $4,500 × 50% = $2,250.
- Total added in year one: $6,000 + $2,250 = $8,250.
- Balance after year one: $10,000 × 1.07 + $8,250 × 1.035 = $19,238.75.
Repeating that for 35 years, with salary rising each year, gives a projected balance of $1,785,211, about $752,236 in today's dollars. You contribute $362,772, your employer adds $136,040, and investment growth contributes $1,276,398.
Worked example 2: how much of the match you capture
The same plan, changing only the percentage you contribute:
| You contribute | Employer adds (total) | Balance at 65 |
|---|---|---|
| 3% of pay | $68,020 | $793,402 |
| 6% of pay | $136,040 | $1,480,039 |
| 8% of pay | $136,040 | $1,785,211 |
Contributing 6% instead of 3% earns $68,020 more in employer matching over the years and grows the balance by $686,637. Contributions above the match limit, like the 8% row, still grow but earn no extra match. That is why capturing the whole match is a common first goal.
Worked example 3: starting later
Someone aged 45 with a $90,000 salary, $60,000 already saved, contributing 12% until 67, with the same match and return assumptions.
| Item | Amount |
|---|---|
| Years of saving | 22 |
| They contribute | $329,797 |
| Employer match | $82,449 |
| Investment growth (including growth on the existing $60,000) | $671,853 |
| Balance at 67 | $1,144,100 |
| In today's dollars | $664,567 |
A higher contribution rate and an existing balance can make up much of the gap from starting later, though nothing replaces extra years of compounding.
Worked example 4: the contribution limit
A 40-year-old earning $250,000 who wants to save 15% would contribute $37,500, more than the limit. The calculator caps the contribution at the limit ($24,500), so in the first year only $24,500 is contributed (the cap is checked each year as salary and age change).
| Age | Employee limit in 2026 |
|---|---|
| 30 | $24,500 |
| 50 and over | $32,500 |
| 61 (ages 60 to 63) | $35,750 |
2026 limits at a glance
| Limit | 2026 amount |
|---|---|
| Employee deferral (401(k), 403(b), TSP) | $24,500 |
| Catch-up, age 50 and over | $8,000 |
| Catch-up, ages 60 to 63 | $11,250 |
| IRA contribution limit | $7,500 |
| IRA catch-up, age 50 and over | $1,100 |
Source: IRS Notice 2025-67. Limits are indexed to inflation and usually change each year.
Getting more from your 401(k)
- Capture the full match. Contribute at least enough to earn all of it.
- Increase contributions with each raise. Even one extra percent a year adds up.
- Watch fees. Low-cost index funds keep more of your return.
- Avoid early withdrawals. They usually bring taxes and a 10% penalty before age 59½, with some exceptions.
Common mistakes to avoid
- Leaving match money unclaimed. Contribute at least up to the match limit.
- Treating one return assumption as a promise. Test lower returns as well.
- Ignoring inflation. The today's-dollars figure shows what the balance might really buy.
- Forgetting vesting. Not all employer money is yours right away.
- Cashing out when changing jobs. Rolling over avoids taxes and penalties.
To see the effect on your paycheck use the paycheck calculator, or explore general growth with the compound interest calculator.
Sources and review
Limits come from the IRS announcement of Notice 2025-67. The projection is a simplified yearly model, and real results depend on returns, fees and plan rules. Last reviewed September 2026. Read about our methodology. This is an estimate and not investment advice.