Free, open-source 401(k) retirement calculator with employer matching and 2026 contribution limits.

Project your retirement savings with employer match, catch-up contributions, the new super catch-up for ages 60-63, and a complete year-by-year breakdown.

Live Demo License: MIT

Use the 401(k) Calculator on BullRun Forever Tools — includes interactive charts, scenario comparison, CSV export, and dark mode.

• 2026 401(k) contribution limits (24,500ドル / 32,000ドル / 35,750ドル)
• Employer matching calculations (configurable match % and cap)
• Catch-up contributions for ages 50+ (7,500ドル)
• NEW: Super catch-up contributions for ages 60-63 (11,250ドル)
• Year-by-year growth breakdown with employer match tracking
• Tax savings estimation from pre-tax contributions
• 30-year extended projection
• Zero dependencies — pure JavaScript math

The SECURE 2.0 Act introduced the super catch-up provision for ages 60-63, allowing an additional 11,250ドル on top of the base limit.

Total Annual Addition Limit (employee + employer): 71,000ドル

npm install
npm run dev

Open http://localhost:5173 to use the calculator locally.

The calculator models year-by-year 401(k) growth including employee contributions, employer matching, and compound returns:

For each year from current age to retirement age:
 1. Determine contribution limit based on age
 2. Calculate employee contribution (salary ×ばつ contribution%, capped at limit)
 3. Calculate employer match (employee contribution ×ばつ match%, capped at matchable salary)
 4. Add both contributions to balance
 5. Apply annual return: growth = balance ×ばつ rate
 6. End-of-year balance = balance + growth

matchableAmount = annualSalary ×ばつ (matchCap / 100)
employeeContributionForMatch = min(employeeContribution, matchableAmount)
employerMatch = employeeContributionForMatch ×ばつ (matchPercent / 100)

Example: Salary 75,000,ドル employer matches 50% up to 6% of salary:

Matchable Amount: 75,000ドル ×ばつ 6% = 4,500ドル
If employee contributes 4,500ドル+:
 Employer Match: 4,500ドル ×ばつ 50% = 2,250ドル/year (FREE money!)

Inputs:

• Current Age: 30, Retirement Age: 65
• Current Balance: 10,000ドル
• Annual Salary: 75,000ドル
• Contribution: 15% (11,250ドル/year)
• Employer Match: 50% up to 6%
• Expected Return: 8%

Year 1:

Employee Contribution: 11,250ドル (under 24,500ドル limit)
Employer Match: min(11,250,ドル 4,500ドル) ×ばつ 50% = 2,250ドル
Total Added: 13,500ドル
Starting: 10,000ドル + 13,500ドル = 23,500ドル
Growth: 23,500ドル ×ばつ 8% = 1,880ドル
Ending Balance: 25,380ドル

After 35 years:

Total Value: ~2,847,000ドル
Your Contributions: ~404,250ドル
Employer Match: ~78,750ドル
Investment Earnings: ~2,364,000ドル
Est. Tax Savings: ~97,020ドル (at 24% bracket)

import { calculate401k } from './src/calculator.js';
const result = calculate401k({
 currentAge: 30,
 retirementAge: 65,
 currentBalance: 10000,
 annualSalary: 75000,
 contributionPercent: 15,
 annualReturn: 8,
 employerMatchPercent: 50,
 employerMatchCap: 6
});
console.log(result.totalValue); // ~2,847,000ドル
console.log(result.totalEmployerContributed); // ~78,750ドル
console.log(result.estimatedTaxSavings); // ~97,020ドル
console.log(result.yearlyBreakdown); // Array of yearly data

{
 totalValue: number, // Final 401(k) balance at retirement
 totalEmployeeContributed: number, // Sum of your contributions
 totalEmployerContributed: number, // Sum of employer match contributions
 totalContributions: number, // Employee + employer total
 totalEarnings: number, // Investment growth
 returnOnInvestment: number, // ROI percentage
 estimatedTaxSavings: number, // Tax savings from pre-tax contributions
 years: number, // Years until retirement
 yearlyBreakdown: [
 {
 year: number,
 age: number,
 startingBalance: number,
 employeeContribution: number,
 employerMatch: number,
 totalContribution: number,
 contributionLimit: number,
 growth: number,
 endingBalance: number,
 totalEmployeeContributed: number,
 totalEmployerContributed: number,
 totalEarnings: number
 }
 ],
 thirtyYearProjection: { // Extended projection (if applicable)
 totalValue: number,
 totalEmployeeContributed: number,
 totalEmployerContributed: number,
 totalEarnings: number
 }
}

The 401(k) is the most widely used retirement vehicle in America:

• 70+ million Americans actively contribute (Investment Company Institute)
• Employer matching — an instant 50-100% return on your contributions
• Tax-deferred growth — investments compound without annual tax drag
• Higher limits — 24,500ドル vs. 7,000ドル for IRAs
• Automatic payroll deductions — set it and forget it
• Average employer match: 4.7% of salary (Vanguard's How America Saves 2025)

An employee earning 60,000ドル who skips the match forfeits 2,820ドル/year in free money.

What are the 2026 401(k) contribution limits? 24,500ドル under 50, 32,000ドル for ages 50+, and 35,750ドル for ages 60-63 (super catch-up via SECURE 2.0 Act).

How does employer matching work? Your employer contributes based on your contributions. Common: 50% match up to 6% of salary. Always contribute enough to get the full match — it's free money.

What happens to my 401(k) if I change jobs? You can leave it, roll it to your new employer's plan, roll it into an IRA, or cash out (not recommended — 10% penalty + taxes).

How much should I contribute? Financial experts recommend 10-15% of gross income for retirement. At minimum, contribute enough for the full employer match.

This calculator is part of the BullRun Forever Toolkit — 16 free financial calculators including:

• Roth IRA Calculator — Tax-free retirement growth
• Investment Calculator — Compound interest projections
• Freedom Number Calculator — FIRE number & 4% rule
• Debt Strategy Planner — Snowball vs. avalanche
• Budget Planner — Personalized budgeting

MIT License — use freely in your own projects.

This calculator is for educational and informational purposes only. It is not financial, tax, or investment advice. Consult a qualified financial advisor for personalized recommendations. Tax laws and contribution limits may change.

Built by BullRun Forever
Free financial tools for everyone.