Free 401(k) Calculator (+ Guide)

What is a 401(k) calculator?

A 401(k) calculator estimates what a 401(k) grows to by retirement, from what you and your employer put in and a yearly return.

This one caps your contributions at the IRS's 2026 limits for your age and shows any match you're missing.

How it works

The calculator works it out on your device, and your numbers stay there.

The 2026 limits

IRS Notice 2025-67 sets the 2026 limits, and the IRS announced them in November 2025.

If your 2025 Social Security wages were over $150,000, your 2026 catch-up has to go in as Roth.

How the match works

A match is written as a share of what you put in, on up to a share of your pay.

At 50% on up to 6%, a $60,000 salary gets up to $1,800 a year: half of the first $3,600 you put in.

Put in less than 6%, and the rest of that match never reaches you.

A worked example

Here's the example the calculator loads: age 30, retiring at 65, a $60,000 salary that rises 2% a year, 6% put in, a 50% match on up to 6%, $10,000 saved and 7% a year.

You'd put in $179,980 over 35 years and your employer $89,990, and growth adds $796,122, for about $1,076,092 at 65.

Put in 3% instead, and the balance at 65 drops to about $591,429, with $900 of match left behind in the first year alone.

Mistakes to avoid

These are the slips that come up most.

• Putting in less than the share your employer matches
• Counting catch-up toward the $72,000 total, when it sits on top
• Forgetting that a raise lifts what you put in and your match
• Reading a traditional 401(k) balance as spending money, before income tax

Who is the 401(k) calculator for?

It's for anyone with a 401(k), or a job that offers one, and these tools help around it.

• Retirement calculator – for your savings across every account
• FIRE calculator – for retiring early
• Compound interest calculator – for growth at any rate
• Coast FIRE calculator – for when you could stop saving

Check your plan's own match and vesting rules, and let the calculator show you what they're worth.