Free Online Calculators, Converters & Tools
Accurate, private, and always free. Every calculation runs in your browser: no sign-ups, no data collection.
Popular Calculators
401(k) Calculator
This tool estimates how your 401(k) balance could grow from salary, deferral rate, employer match, and years to retirement, with 2026 IRS deferral caps applied. Use it to see whether you are on track for the full match and how headline dollars compare to todayโs spending power. Estimates only; not tax or financial advice.
Age Calculator
Computes chronological age in years, months, and days from birth through any as-of date, using calendar-accurate month lengths and leap-year rules. Week-through-second totals and a next-birthday countdown are included. Western age only, not Korean age or insurance nearest-birthday rounding.
Amortization Calculator
Detailed month-by-month breakdown of principal and interest with 2026 interest-efficiency tracking.
Auto Loan Calculator
Calculate monthly car payments, total interest, and trade-in impact with 2026 equity tracking.
BMI Calculator
Calculate your Body Mass Index based on height and weight.
Calorie Calculator
Calculate daily calorie needs using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle formulas. Get TDEE, target intake for weight loss/gain, macro splits, and zig-zag calorie cycling schedules.
Compound Interest Calculator
Calculate how an initial investment grows with regular contributions, flexible compounding frequencies, and optional annual contribution increases. Includes employer match modeling and inflation-adjusted real value alongside the nominal balance. Share your scenario via a copyable link.
Credit Cards Payoff Calculator
The Credit Cards Payoff Calculator compares the Snowball and Avalanche payoff methods side by side for up to 20 cards. Enter each balance, regular APR, and minimum; add intro APR windows, balance-transfer fees, or auto-calculated issuer minimums in More options. Daily-compounded interest matches typical issuer math. Estimates only; not credit counseling or financial advice.
Distance Calculator
This calculator finds straight-line distance between two points in 2D or 3D using the Pythagorean theorem, or air distance between two lat/lon pairs using the Haversine great-circle formula (R = 6,371 km). Geographic mode includes an interactive map and live formula substitution. Crow-flies onlyโnot driving or walking routes.
House Affordability Calculator
Compare how much house you can afford with Conventional, FHA, and VA loans.
Loan Calculator
Work out monthly payments and total interest for standard, deferred, or bond-style loans. Add extra paydowns and compare APR and APY in one place.
Mortgage Calculator
This calculator estimates fixed-rate P&I from the standard amortization formula, then adds property tax, insurance, PMI you enter when down payment is under 20%, and optional extras. ARMs are not modeled; everything runs locally in your browser.
Mortgage Payoff Calculator
This calculator compares standard vs. accelerated mortgage payoff from remaining balance, current P&I payment, interest rate, and time left. It models additional monthly principal, one-time and annual lump sums, and a simplified bi-weekly equivalent (one extra P&I payment per year spread monthly). Outputs debt-free date, interest saved, time removed, path comparison, and a cumulative-interest chart. It does not model escrow, PMI, or ARM rate changes. Illustrative only; not a loan offer or financial advice.
Percentage Calculator
Four modes: what is X% of Y, X is what percent of Y, percent change (increase or decrease), and percent difference. Logic Trace and ratio visualizer; decimal places 0โ6. Runs locally.
Retirement Calculator
Estimate how much you need to save for retirement.