Financial calculators that run the numbers for you.
Your 401(k), taxes, take-home pay and retirement date, worked out paycheck by paycheck. Built for people with more than one job, RSUs and real-life tax questions. Free, no sign-up, and your numbers stay in your browser.
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Mega Backdoor RothHow much can I get into Roth this year?Sets your 401(k) percentages across every job so you max the mega backdoor without losing match.For example: With after-tax contributions, one job’s 401(k) can take $72,000 a year, not just $24,500.RSU PlannerWhy do I owe tax on my RSUs?Every vest priced and taxed, what you’ll still owe at tax time and how to pay it, and offers compared after tax.For example: Vests withheld at 22% with income in the 35% bracket: about $16,417 still owed for 2026.Comp TrackerHow much stock do I still have coming?Every grant’s vests by quarter, history at the price and rate on the day, and a promotion or a currency move as what-ifs.For example: Two grants in yen-listed stock: $150,411 still to vest, $78,505 of it in the next 12 months.FI/RE CalculatorWhen can I stop working?Projects your savings with fixed, historical or Monte Carlo returns and shows the age work becomes optional.For example: Age 30, $50,000 saved, saving $30,000 a year: work optional at 44.Paycheck CalculatorWhat will my paycheck be?Take-home after federal, FICA and state tax, every check of the year, compared across up to six states.For example: $100,000 salary in Washington: $3,045 every two weeks after tax.Mortgage CalculatorWhat will this house cost me a month?Your full payment with tax, insurance and PMI, how it pays down, and up to three loans side by side.For example: $425,000 home, 20% down at 6.792%: $2,728 a month with tax and insurance.RSU Vest TaxWill my next vest leave me owing?One vest’s withholding against the tax it really adds, and how much of it to set aside.For example: A $48,000 vest on a $220,000 salary: about $4,800 more to set aside.Debt PayoffWhen will I be debt-free?Your debt-free date, the interest you’ll pay, and avalanche against snowball.For example: $46,500 across 4 debts, $300 extra a month: debt-free by Aug 2030.Home AffordabilityHow much house can I afford?The price your income supports under the 28/36 rule and the full monthly payment it means.For example: $150,000 income, $80,000 down: up to $513,000 at $3,495 a month.Moving and State TaxWould moving states pay off?Take-home in two states, the rent difference, and how soon the move pays for itself.For example: $180,000 from California to Washington: $12,767 more take-home a year.
Why the 401(k) optimizer exists
The 401(k) has two limits. The one most people know, $24,500 of pre-tax and Roth deferrals, is shared across every job you have. The other, $72,000 of total additions, applies at each employer. If your plan takes after-tax contributions and converts them to Roth, the gap between the two is the mega backdoor Roth.
Getting it right means pacing contributions so you don’t lose match, coordinating limits across jobs, and knowing what your withholding misses. The optimizer does that math paycheck by paycheck; the full guide explains it step by step.
Popular guides
All articlesGuide · 8 min readRoth vs Pre-Tax 401k: Which Is Better for You in 2026?A direct comparison of Roth and pre-tax 401(k) for 2026.Guide · 4 min readThe Mega Backdoor Roth: A Complete Guide for 2026How to get up to $72,000 a year into your 401(k).Guide · 6 min readHow Much Should I Contribute to My 401k in 2026?A priority order for picking your contribution rate.Guide · 5 min readHow to Avoid Losing Your 401k Employer Match When Front-LoadingWhy front-loading can cost you match, and how to pace it.Guide · 5 min readUnderstanding Your Mortgage Payment: PITI, PMI, and the Math That Actually MattersThe five parts of a payment and what a quarter point costs.Guide · 10 min readIs It Safe to Retire at a Market Top? Hitting Your FIRE Number in a Melt-Up (2026)What hitting your number in a melt-up means for retiring now.