# 401k calculator

> Calculate your 401(k) balance at retirement from salary, contribution rate and a two-tier employer match, with 2026 IRS limits and catch-up.

Interactive version: https://www.calcopenly.com/finance/401k-calculator
Subject: Finance calculators

The projection runs one year at a time. Each year your salary grows, your contribution is the percentage you choose capped at the IRS elective deferral limit for your age, and the employer adds its match: a rate on your contributions up to one slice of salary, then a second rate on the next slice. Contributions go in monthly and the balance grows at the return you enter.

With the defaults, a 30-year-old earning $75,000 who saves 10% with a match of 100% on the first 3% and 50% on the next 2% puts in $7,500 this year and receives $3,000. Salary rising 3% a year and a 7% return build $2,807,522.39 by 67, or $1,349,325.95 in today's dollars at 2% inflation.

For 2026 the deferral limit is $24,500, plus $8,000 from age 50 or $11,250 at ages 60 to 63 (IRS Notice 2025-67). Later limits rise with the inflation you enter, in $500 steps. Taxes, fees and vesting schedules are not modeled.

## Inputs

- **Current age**: Your age at the end of this year; catch-up limits follow the age you reach in each calendar year
- **Retirement age**
- **Annual salary**
- **Salary increase (per year)**
- **Your contribution (% of salary)**
- **Employer match, first tier**: Share of your contributions the employer matches. 100% of the first 3% and 50% of the next 2% is the IRS safe harbor basic match; enter 0 for no match
- **First tier limit (% of salary)**: The first rate applies to your contributions up to this share of salary
- **Employer match, second tier**
- **Second tier limit (% of salary)**: The second rate applies to the next slice of salary above the first tier
- **Current 401(k) balance**
- **Investment return (per year)**
- **Inflation (per year)**: Raises the IRS limits each year in the steps the tax code uses, and converts the final balance to today's dollars. 2% is the Federal Reserve's target
- **Apply IRS contribution limits**

## Results

- Balance at retirement — main result
- Balance in today's dollars
- Your contributions
- Employer contributions
- Investment growth
- Your contribution this year
- Employer match this year
- Match left unclaimed this year
- Your 2026 deferral limit
- Years of contributions

## Formula

$$
B_{k+1} = B_k(1+r) + \frac{C_k}{12}\cdot\frac{(1+j)^{12}-1}{j},\quad j=(1+r)^{1/12}-1,\quad C_k = \min(p\,S_k,\ L_k) + M_k
$$

## Worked examples

### Defaults: age 30, $75,000, 10% with a 100%/3% + 50%/2% match

- Current age: 30 years
- Retirement age: 67 years
- Annual salary: 75,000
- Salary increase (per year): 3%
- Your contribution (% of salary): 10%
- Employer match, first tier: 100%
- First tier limit (% of salary): 3%
- Employer match, second tier: 50%
- Second tier limit (% of salary): 2%
- Current 401(k) balance: 25,000
- Investment return (per year): 7%
- Inflation (per year): 2%
- Apply IRS contribution limits: yes
- **Balance at retirement: 2,807,522.39**
- **Balance in today's dollars: 1,349,325.95**
- **Your contributions: 496,306.67**
- **Employer contributions: 198,522.67**
- **Your contribution this year: 7,500.00**
- **Employer match this year: 3,000.00**
- **Match left unclaimed this year: 0.00**
- Checked against: Python decimal (prec 50) year-by-year model: monthly deposits at the effective monthly rate, limits indexed in $500/$1,000/$5,000 steps

### Zero return and no salary growth

- Current age: 40 years
- Retirement age: 45 years
- Annual salary: 60,000
- Salary increase (per year): 0%
- Your contribution (% of salary): 6%
- Employer match, first tier: 100%
- First tier limit (% of salary): 3%
- Employer match, second tier: 50%
- Second tier limit (% of salary): 2%
- Current 401(k) balance: 10,000
- Investment return (per year): 0%
- Inflation (per year): 0%
- **Balance at retirement: 40,000.00**
- **Your contributions: 18,000.00**
- **Employer contributions: 12,000.00**
- **Investment growth: 0.00**
- **Employer match this year: 2,400.00**
- Checked against: Hand calculation: 5 × (3,600 + 1,800 + 600) + 10,000 = 40,000

### Age 61 to 63 super catch-up, salary above the compensation limit

- Current age: 61 years
- Retirement age: 64 years
- Annual salary: 400,000
- Salary increase (per year): 0%
- Your contribution (% of salary): 20%
- Employer match, first tier: 100%
- First tier limit (% of salary): 3%
- Employer match, second tier: 50%
- Second tier limit (% of salary): 2%
- Current 401(k) balance: 500,000
- Investment return (per year): 6%
- Inflation (per year): 0%
- **Your contribution this year: 35,750.00**
- **Employer match this year: 14,400.00**
- **Your 2026 deferral limit: 35,750.00**
- **Your contributions: 107,250.00**
- **Balance at retirement: 759,509.93**
- Checked against: IRS Notice 2025-67: 24,500 + 11,250 = 35,750; match on the $360,000 compensation cap = 10,800 + 3,600; balance from Python decimal

### Age 50 catch-up with limits indexed at 2.5%

- Current age: 50 years
- Retirement age: 55 years
- Annual salary: 200,000
- Salary increase (per year): 2%
- Your contribution (% of salary): 20%
- Employer match, first tier: 50%
- First tier limit (% of salary): 6%
- Employer match, second tier: 0%
- Second tier limit (% of salary): 0%
- Current 401(k) balance: 150,000
- Investment return (per year): 6%
- Inflation (per year): 2.5%
- **Your contribution this year: 32,500.00**
- **Employer match this year: 6,000.00**
- **Your contributions: 169,000.00**
- **Balance at retirement: 432,027.11**
- Checked against: IRS Notice 2025-67 (24,500 + 8,000); later years and balance from Python decimal with increases rounded down to $500

### Section 415(c) cap on employer contributions

- Current age: 40 years
- Retirement age: 41 years
- Annual salary: 300,000
- Salary increase (per year): 0%
- Your contribution (% of salary): 10%
- Employer match, first tier: 200%
- First tier limit (% of salary): 10%
- Employer match, second tier: 0%
- Second tier limit (% of salary): 0%
- Current 401(k) balance: 0
- Investment return (per year): 5%
- Inflation (per year): 0%
- **Your contribution this year: 24,500.00**
- **Employer match this year: 47,500.00**
- **Balance at retirement: 73,635.47**
- Checked against: Section 415(c) limit $72,000 (Notice 2025-67): 72,000 − 24,500 = 47,500; balance from Python decimal

## Questions

### How much can I contribute to a 401(k) in 2026?

$24,500 of elective deferrals, the limit in IRS Notice 2025-67. From the year you turn 50 you can add a catch-up of $8,000, for $32,500 in total, and in the years you turn 60, 61, 62 or 63 the catch-up is $11,250, for $35,750. Employee and employer contributions together, excluding catch-up, are capped at $72,000 under section 415(c).

### How does a 401(k) employer match work?

The employer adds a percentage of what you contribute, up to a share of your pay. Under the IRS safe harbor basic formula, 100% of the first 3% and 50% of the next 2%, a $75,000 earner who contributes at least 5% ($3,750) receives $2,250 + $750 = $3,000. Contributing 2% ($1,500) would earn only $1,500, leaving $1,500 of match unclaimed.

### What is the 401(k) super catch-up for ages 60 to 63?

SECURE 2.0 raised the catch-up limit for people who turn 60, 61, 62 or 63 during the year. For 2026 it is $11,250 instead of the $8,000 that applies from age 50, so the total deferral limit at those ages is $35,750. At 64 the regular $8,000 catch-up applies again.

### Do high earners have to make catch-up contributions as Roth?

Yes, from 2026. If your 2025 wages from the employer sponsoring the plan were above $150,000, your 2026 catch-up contributions must be designated Roth, meaning they are made after tax (IRS Notice 2025-67, section 414(v)(7)). Your regular $24,500 of deferrals can still be pre-tax. The balance projected here is the same either way.

### How much will my 401(k) be worth at retirement?

It depends mostly on the years left and the return. With the defaults, $7,500 a year from you and $3,000 from the employer, both rising 3% a year, grow to $2,807,522.39 over 37 years at 7%. Of that, $694,829.34 is contributions and $2,087,693.05 is investment growth. At a 5% return the same savings reach $1,814,452.59, 35% less.

### How accurate is the 401k calculator?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 5 worked examples whose answers come from independent sources; for example, “Defaults: age 30, $75,000, 10% with a 100%/3% + 50%/2% match” is checked against Python decimal (prec 50) year-by-year model: monthly deposits at the effective monthly rate, limits indexed in $500/$1,000/$5,000 steps.

### Where does the method come from?

IRS Notice 2025-67: 2026 amounts relating to retirement plans and IRAs; IRS news release IR-2025-111: 401(k) limit increases to $24,500 for 2026; IRS: Operating a 401(k) plan (safe harbor matching formula); 26 U.S.C. 402(g), 414(v) and 415(c): deferral, catch-up and annual additions limits.

## Sources

- [IRS Notice 2025-67: 2026 amounts relating to retirement plans and IRAs](https://www.irs.gov/pub/irs-drop/n-25-67.pdf)
- [IRS news release IR-2025-111: 401(k) limit increases to $24,500 for 2026](https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500)
- [IRS: Operating a 401(k) plan (safe harbor matching formula)](https://www.irs.gov/retirement-plans/operating-a-401k-plan)
- [26 U.S.C. 402(g), 414(v) and 415(c): deferral, catch-up and annual additions limits](https://www.law.cornell.edu/uscode/text/26/414)

_Note: financial information, not professional advice._