Savings and budgeting calculators that show their work
Every tool on this site pairs an interactive calculator with the formula behind it, the assumptions it makes, and worked examples. No sign-up, no email capture, no stored data — the maths runs entirely in your browser.
Calculators
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Compound Interest
Project monthly deposits over decades, with the formula and a year-by-year chart.
50/30/20 Budget
Split take-home pay into needs, wants, and savings — on any pay schedule.
APY vs. APR Calculator
The same rate compounded daily vs. annually: effective APY, yield gap, and the dollar spread.
Savings Goal Timeline
How long a target takes, or the monthly deposit a deadline actually demands.
Dividend Reinvestment (DRIP)
Reinvesting dividends vs. taking them as cash: the compounding edge, in dollars.
High-Yield Savings
See in dollars what a higher APY is worth against your current rate.
Certificate of Deposit
Maturity value, effective APY, and what an early withdrawal penalty costs.
Snowball vs. Avalanche
See the actual months and dollars that separate snowball from avalanche for your debts.
Sinking Fund Breakdown
The monthly amount each sinking fund needs, plus the combined total across all of them.
Inflation-Adjusted Goal
What today's goal actually costs in future dollars, and the deposit that really gets you there.
Credit Card Payoff
Compare paying only the minimum to a fixed monthly amount on one card balance.
Emergency Fund Calculator
Expenses times months of coverage sets the target, plus the contribution or timeline to close the gap.
Rule Of 72 Calculator
Compare the 72/rate shortcut to the exact doubling-time formula.
Debt Consolidation
One consolidation loan or keep debts separate — compare total interest, payment, and payoff time.
Student Loan Payoff
Compare the standard repayment schedule to paying extra toward principal.
Dollar-Cost Averaging
DCA vs. a lump sum under the same assumed return: ending value, the gap, and cost per share.
Vacation Savings Calculator
A trip cost and a departure date become a per-paycheck savings amount, weekly or biweekly.
Mortgage Payment Calculator
Principal, interest, property tax, insurance, and PMI, plus total interest over the life of the loan.
Mudaraba Term Deposit
Maturity value and profit share across a provisional profit-rate band.
Mortgage Payoff Calculator
Extra principal payments vs. the standard schedule: payoff time and interest saved.
How Much House Can I Afford
Your income, debts, down payment, and rate, priced through the 28/36 rule into a max home price.
Mortgage Refinance Break-Even
When a refinance actually pays for itself: payment and interest break-even months against closing costs.
FIRE Calculator
Your FI number from the 4% rule, plus the savings rate and years to financial independence.
401(k) Calculator
Your 401(k) balance at retirement, including employer match, in nominal and today's dollars.
Roth vs. Traditional IRA
Which IRA keeps more at retirement, for the same cost today: Roth or Traditional?
Savings By Age
Project your retirement balance against the 1x/3x/6x/8x/10x salary benchmark at every age.
Savings Rate Retirement Date
Turn your savings rate into a retirement date: monthly savings, FI number, and years to FI.
Take-Home Pay
Gross salary through 2026 federal tax, FICA, and state tax — net annual pay and per paycheck.
Auto Loan
Monthly payment and total cost of a car loan, including sales tax and trade-in.
Hourly to Salary
Hourly wage to annual salary and back — daily, weekly, biweekly, monthly, and yearly equivalents.
Rent vs Buy
Net wealth after N years of owning versus renting and investing the same money.
529 College Savings
Projected 529 balance against the future cost of college, with the gap and the deposit that closes it.
HSA Calculator
Project your HSA balance at retirement from contributions, employer money, and medical spending.
Inflation Calculator
See how inflation erodes the value of money over time, in real dollars and future costs.
Net Worth Calculator
Your assets minus debts today, projected forward with deposits and returns.
Backdoor Roth IRA Calculator
Check the pro-rata tax cost of a backdoor Roth conversion and the growth that follows.
CD Ladder
Blended yield, staggered maturities, and what annual liquidity costs against a single long CD.
Personal Loan
Monthly payment, total interest, and the true effective APR once an origination fee is deducted.
Subscription Cost Audit
What your subscriptions really cost per month, per year, and if invested instead.
Browse by topic
Every calculator sits in one of six topics. Start with the budgeting calculators to size the surplus you can save, follow it through savings goals, debt payoff, mortgages, and compound growth, and finish at the retirement calculators — each topic page explains the questions its tools answer and how they fit together.
From the blog
Dollar-Cost Averaging vs. Lump Sum: What the Data Shows
A $100,000 inheritance, a diner booth, and what Vanguard's 85-year study actually found about dollar-cost averaging vs. investing it all at once.
How an Average Engineer Retired at 43: The 4-Stage Blueprint
How a Ford engineer retired at 43 with a $1,000,000 portfolio: the 4-stage blueprint, the exact savings math, and the calculators to run your own numbers.
How to use this site
Start with the 50/30/20 budget calculator to establish how much of your take-home pay is genuinely available to save — or the take-home pay calculator if you want the gross-to-net breakdown first. Take that monthly figure to the savings goal timeline calculator to find out when a specific target is reachable, or what deposit a deadline actually demands. Then use the compound interest calculator to see what the same habit produces over a multi-decade horizon, and the FIRE calculator to size the portfolio that would replace your expenses entirely — your FI number from the 4% rule, and how many years your savings rate needs to get there — or thesavings rate retirement date calculatorto see the calendar year a given savings rate buys. Then use the HSA calculator to see how a tax-free health savings account compounds alongside it, or the 401(k) calculator to model an employer match.
If debt is the more urgent problem, the debt snowball vs. avalanche calculator compares the two payoff orderings side by side, and the credit card payoff, student loan payoff, and debt consolidation calculators size the same trade-off for one specific balance. Shopping for a new loan instead? The personal loan calculator prices the payment and the effective APR once an origination fee comes off the top. Already have that covered? The emergency fund calculator turns a target number of months' expenses into a concrete dollar figure and a funding timeline — or break that figure into separate sinking funds for car repairs, gifts, and home maintenance. If the budget will not stretch, the subscription cost audit calculator prices a stack of small recurring charges in one monthly figure — and shows what cancelling the worst of them would free up.
Planning a home purchase? The house affordability calculator applies the 28/36 rule to your income and debts, the mortgage payment calculator prices the monthly cost, and the rent vs. buy calculator compares owning with renting and investing the difference. Already own? The mortgage payoff calculator and mortgage refinance break-even calculator size early-payoff and refinance decisions. Financing a car instead? The auto loan calculator works out the payment from price, down payment, trade-in, and tax.
Short-term goals deserve their own math: the vacation savings calculator turns a trip cost and weeks until departure into a per-paycheck amount, while college savers can project a 529 plan against the future cost of school. For lump sums sitting idle, compare a certificate of deposit, a high-yield savings account, or a Shariah-compliant Mudaraba term deposit — and use the inflation calculator or the inflation-adjusted savings goal calculator to keep every figure in real dollars. Committing part of it for a few years without giving up all access? The CD ladder calculator shows what staggered maturities preserve — and what they cost next to one long certificate.
Want a mental shortcut? The Rule of 72 calculator estimates doubling time in your head, and the dollar-cost averaging calculator compares steady investing with a lump sum. For the full picture — assets minus liabilities — the net worth calculator tracks wealth across account types, and the Roth vs. Traditional IRA and backdoor Roth IRA calculators model the tax choice behind it.
Adjusting any input updates the address bar, so a filled-in calculation can be bookmarked or shared as a link without an account.
What we do not do
We do not sell financial products, take affiliate commissions on account referrals, or collect the numbers you type. Calculations execute in your browser and are never transmitted to a server. The site is funded by display advertising, which is disclosed in full in our privacy policy.
Everything published here is educational information, not personalised financial advice. See the editorial and financial disclaimer for the limits of what these tools can tell you.