401k Calculator
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Project your 401k balance at retirement. See exactly how much your employer match is worth and how much interest you'll earn over time.
Projected 401k Balance
$0
📐 Formula
Future Value = P(1+r)^n + PMT × [(1+r)^n - 1] / r, where P=current balance, r=monthly rate, PMT=monthly contribution, n=months
How to Use the 401k Calculator
Enter your current balance
Input your existing 401(k) balance. If starting fresh, enter 0. An existing balance compounds alongside new contributions — even $5,000 now significantly impacts the 30-year outcome.
Set your monthly contribution
Enter how much you contribute monthly. To convert an annual percentage to a monthly figure: Annual Salary × Contribution% ÷ 12.
Add your employer match
Input match percentage and cap. A common structure is 100% match up to 3% of salary — contributing less than 3% leaves free compensation unclaimed.
Set return rate and years
Use 7% for a historical equity average after inflation. Adjust to 5–6% for a blended stock/bond portfolio, or 8–9% for aggressive equity weighting.
Why the Employer Match Is Your Highest-Return Investment
An employer match provides an immediate 50–100% return on your contribution before a single dollar of market growth. If your employer matches 100% up to 3% of a $70,000 salary, contributing 3% ($2,100) earns you $4,200 in that account immediately — a guaranteed 100% return in year one. No market investment offers a guaranteed return comparable to this. Contributing less than the full match is voluntarily declining part of your compensation package.
After capturing the full match, the next priority is maximising the 401(k) to the annual IRS limit: $23,500 in 2026 ($31,000 for ages 50–59 and 64+; $34,750 for the new 60–63 "super catch-up" under SECURE 2.0). Every dollar contributed reduces your current-year taxable income at your marginal rate.
The Compounding Timeline: Why Starting Early Dwarfs Amount
A 25-year-old saving $300/month at 7% accumulates approximately $940,000 by age 65. A 35-year-old saving the same amount accumulates only $454,000 — less than half — despite 30 full years of contributions. The first decade of compounding accounts for nearly half the terminal value. This is the single most important insight in retirement planning: time in the market is more powerful than amount contributed. The 401(k) calculator makes this visible instantly by adjusting the start age.
How to Calculate 401k Growth by Hand: Worked Example
Take an $80,000 salary, an 8% employee contribution, and a typical employer match of 50% of contributions up to 6% of salary.
Step 1 — annual employee contribution. $80,000 × 0.08 = $6,400 per year, deducted pre-tax.
Step 2 — the match. The employer matches half of the first 6% of salary: $80,000 × 0.06 × 0.50 = $2,400. Total flowing into the account: $8,800 per year.
Step 3 — compound for 25 years at 7%. Future value of the annual stream: $8,800 × [(1.07²⁵ − 1) ÷ 0.07] = $8,800 × 63.249 ≈ $556,600.
Without the match, the same math on $6,400 alone reaches about $404,800. The match — money that required nothing but enrolling at 6% or better — accounts for roughly $151,800 of the final balance. That is the arithmetic behind the advice to never contribute below the match threshold.
How much does raising your contribution 1% actually cost?
Less than it appears, because contributions are pre-tax. Moving from 8% to 9% on $80,000 adds $800 per year to the account, but for someone in the 22% bracket take-home pay falls by only about $624 — the other $176 is tax that would otherwise have gone to the IRS this year. Meanwhile that extra $800 per year compounds to roughly $50,000 more over the 25-year projection above.
Traditional or Roth 401k: Which Grows Your Spendable Money More?
Does pre-tax or after-tax contribution win?
The deciding variable is your tax rate now versus in retirement. Traditional contributions skip tax today and pay it on withdrawal; Roth contributions pay tax today and withdraw free. If your bracket will be lower in retirement — true for most people whose retirement spending is below their peak salary — traditional wins. Early-career workers in low brackets, or anyone expecting higher future rates, lean Roth. Splitting contributions between both hedges the uncertainty, since nobody knows tax law 25 years out.
What happens to the match when you change jobs?
Your own contributions are always 100% yours. Employer match dollars may be subject to a vesting schedule — commonly 3-year cliff or 6-year graded. Leaving one year before a cliff vests can forfeit thousands; the vesting date belongs on the same calendar as salary negotiations when weighing a job offer.
Frequently Asked Questions
Sources & Methodology
Calculations are based on the most current publicly available data from authoritative government and industry sources: