A growing collection of free utilities — calculators, converters, and generators that work right in your browser. No sign-up, no install.
Calculate your Body Mass Index in metric or imperial units, with category interpretation.
Estimate your daily calorie needs using the Mifflin-St Jeor BMR formula and an activity multiplier. Includes targets for weight loss and gain.
Estimate ideal body weight using four classic clinical formulas plus the WHO healthy BMI range. Choose by height and sex.
Estimate your pregnancy due date from the last menstrual period or conception date. Includes gestational weeks and trimester.
Estimate your recommended daily water intake based on body weight and activity level. Shown in liters, ounces, cups, and bottle equivalents.
Calculate running pace from distance and time, or finish time from a target pace. Output per-km, per-mile, km/h, and mph.
Calculate daily protein, fat, and carb targets from your TDEE and weight goal. Uses 30/30/40 split with a protein floor of 1.6 g/kg.
Calculate basal metabolic rate via three formulas: Mifflin-St Jeor (default), Harris-Benedict (legacy), and Katch-McArdle (uses lean mass).
Estimate your ovulation date, 6-day fertile window, next period, and due date if conception occurs — based on last menstrual period and cycle length.
Estimate body fat percentage using the US Navy method (waist, neck, and hip for women). Returns fat mass, lean mass, and fitness category.
Find your current pregnancy week, day-of-week, trimester, due date, and days remaining — all from your last menstrual period.
Estimate your 1RM (one-rep max) from any submaximal lift. Five validated formulas (Epley, Brzycki, Lombardi, O'Conner, Lander) plus a training-percentage table.
Calculate your max heart rate and 5 training zones (recovery, fat burn, aerobic, threshold, max). Karvonen formula uses resting HR for accuracy.
Calculate how long it takes to reach your target weight at a given daily calorie deficit. Returns target date, weeks, months, and weekly weight loss.
Calculate WHR (waist circumference / hip circumference). Categorizes risk level by sex per WHO thresholds.
Convert between metric and imperial length units instantly. Includes mm, cm, m, km, inches, feet, yards, and miles.
Convert between Celsius, Fahrenheit, Kelvin, and Rankine. All four scales update at once.
Convert between metric and imperial mass units. Includes mg, grams, kilograms, tonnes, ounces, pounds, and stones.
Convert between metric, imperial, and Japanese area units. Includes m², km², hectare, ft², acre, mile², and tsubo.
Convert between time units from milliseconds to years. Months use the average length, years use the Julian definition.
Convert digital storage sizes between bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Switch between SI (1000) and IEC binary (1024).
Convert between metric and US/UK volume units. Includes mL, liters, m³, teaspoons, tablespoons, fluid ounces, cups, pints, quarts, and gallons.
Convert between common speed units: km/h, mph, m/s, ft/s, knots, and Mach. Used for vehicles, weather, aviation, and physics.
Convert vehicle fuel economy between mpg (US), mpg (UK), km per liter, and L per 100 km. Distinguishes US and UK gallons.
Convert between pressure units: Pascal, bar, psi, atmosphere, mmHg, Torr, and more. All units update simultaneously when you change one.
Convert angles between degrees, radians, gradians, turns, arcminutes, and arcseconds. All 6 units update simultaneously.
Convert between power units: watts, kilowatts, megawatts, mechanical horsepower, metric horsepower (PS), BTU/hour, foot-pounds/second, cal/s, kcal/h.
Calculate exact age in years, months, days, weeks, and hours from any birth date to any target date.
Live countdown to any future date and time. Updates every second; works for events, deadlines, launches, vacations.
Convert between Unix timestamps (seconds or milliseconds) and human-readable dates. Shows ISO 8601, local time, and relative time.
Add or subtract years/months/days from a date, or find the precise difference between two dates including business days.
Convert one moment in time across multiple timezones at once. Add or remove zones; great for scheduling international meetings.
Test cron expressions and see the next 5 scheduled runs in your local timezone. Validates fields, supports ranges, lists, and steps.
Classic Pomodoro Technique timer: 25 minutes focus + 5 minutes short break, every 4th break is 15 minutes. Audio chime when each phase ends.
Check if a year is a leap year and see why. Shows February days, year days, and the previous and next leap years.
Count business days between two dates, excluding weekends and any holidays you list. Customizable: include Saturday or Sunday as workdays if needed.
Find the ISO 8601 week number, ISO weekday, and week date range for any calendar date. Includes day-of-year and weeks-in-year.
Calculate the exact age difference between two people in years, months, days, plus totals in weeks, days, and hours.
See the moon phase, age in days, illumination percentage, and dates of the next new and full moons for any calendar date.
High-precision in-browser stopwatch with start/pause, lap recording, and split-time calculation. Millisecond display, monotonic clock for accuracy.
Three percentage calculators in one: 'X% of Y', 'X is what % of Y', and percentage change between two values.
Calculate your GPA on the 4.0 scale, weighted by course credit hours. Add as many courses as you need.
Convert numbers between binary, octal, decimal, and hexadecimal. Validates input for the chosen base and shows all four representations.
Generate random integers in any range using your browser's secure random API. Optionally enforce uniqueness for lottery, raffle, or sample-without-replacement use cases.
Calculate how much paint you need based on room dimensions, number of coats, and doors/windows. Output in liters or gallons.
Calculate width or height to preserve a target aspect ratio. Common ratios (16:9, 9:16, 1:1, 4:3, 21:9) one-click presets included.
Roll any number of dice with any number of sides. Cryptographically random, with modifier (+N), running total, and roll history.
Compute mean, median, mode, standard deviation, variance, range, quartiles, and more from a list of numbers. Sample or population mode.
Check whether a number is prime. If not, see its prime factorization. Plus the next and previous prime numbers.
Solve any quadratic equation. Returns real or complex roots, the discriminant, and the parabola's vertex coordinates.
Add, subtract, multiply, or divide two fractions. Returns simplified form, decimal equivalent, and mixed-number representation.
Find the greatest common divisor (GCD) and least common multiple (LCM) of two or more integers, plus each number's prime factorization.
Compute a triangle's area, perimeter, sides, and angles. Three modes: right triangle (Pythagorean), three sides (SSS), or two sides + included angle (SAS).
Convert decimal numbers to/from scientific (1.23 × 10^4) and engineering (1.23e3) notation. Bidirectional, with E-notation output.
Calculate n! (factorial), P(n,k) permutations, and C(n,k) combinations. Handles large integers via BigInt up to n=5000.
Calculate tip and split a restaurant bill across any number of people. Quick presets for common tip percentages.
See how an investment grows over time with compounding interest and optional monthly contributions. Customizable compounding frequency.
Calculate the monthly payment for any fixed-rate loan, plus total amount paid and total interest over the life of the loan.
Add sales tax to a pre-tax amount or extract the tax from a tax-inclusive total. Works for any tax rate (sales tax, VAT, GST).
Calculate the final price after a percentage discount, plus optional sales tax. See how much you saved at a glance.
Calculate the full monthly mortgage payment including principal, interest, property tax, insurance, PMI (if applicable), and HOA fees.
Calculate sell price, gross profit, and gross margin from cost and markup percentage. Distinguishes markup vs margin clearly.
Compare items by unit price (price per gram, ounce, count, etc.). Add as many items as you want; the cheapest is highlighted.
Validate a credit card number's checksum (Luhn algorithm) and detect the issuing brand. Browser-only — your card number never leaves your device.
Find out how long it takes to reach a savings goal given a starting balance, monthly contribution, and annual return.
Convert pay between hourly, daily, weekly, monthly, and annual rates. Useful for comparing job offers and contractor rates.
Project your retirement savings with monthly contributions, expected return, and inflation. Shows nominal balance, today-dollar value, and 4%-rule monthly income.
Calculate simple interest on a principal amount given an annual rate and time. Returns interest earned and total balance.
Calculate monthly auto-loan payment, total interest, and total cost. Includes down payment and trade-in value adjustments.
Calculate crypto trading profit, ROI, and fee impact. Enter amount held, buy price, sell price, and exchange fee % — get net profit after both buy and sell fees.
Calculate stock trade profit including buy/sell commissions, dividends received, and capital-gains tax. Returns net after-tax profit and ROI.
See how inflation erodes purchasing power: future cost of today's money, plus today's value of a future amount.
Calculate the size of an emergency fund (3, 6, 9, or 12 months of expenses) and how long it takes to build at your savings rate.
Calculate income tax owed using progressive brackets. Japan, US single, and US married-filing-jointly. Returns total tax, effective rate, marginal rate, and per-bracket breakdown.
Add or remove VAT/GST/sales tax. Quick presets for Japan, UK, EU countries, Australia, Canada, China.
Calculate return on investment (ROI) % and annualized return for any holding period. Works for any investment: stocks, real estate, business, side projects.
Calculate fuel cost for any trip from distance, fuel efficiency (MPG or km/L), and fuel price. Optional split between passengers.
Calculate net worth: total assets minus total liabilities. Categorized inputs for cash, investments, retirement, real estate, vehicles, mortgage, loans, credit cards.
Estimate how long an investment takes to double using the Rule of 72, or solve for the rate needed to double in a given period. Compares against exact compound math.
Calculate compound annual growth rate from start value, end value, and number of years. Returns CAGR %, total return %, and multiplier.
Generate a full month-by-month amortization schedule for any fixed-rate loan. Shows principal/interest split per payment, ending balance, and a CSV export.
Calculate your front-end and back-end debt-to-income ratios from monthly income and debt payments. See how lenders categorize you.
Calculate how much life insurance you actually need using the DIME method: Debt + Income replacement + Mortgage + Education.
Calculate ROAS from revenue and ad spend, plus the profit-adjusted ROAS using gross margin. See breakeven multiple instantly.
Calculate your overall credit utilization ratio and per-card ratios. See exactly how lenders score your card balances against limits.
Calculate the regular payout from an annuity given principal, interest rate, and payout period. Supports monthly or annual distributions.
Compare your current mortgage against a refinance offer. See monthly payment change, lifetime interest savings, and the break-even month after closing costs.
Compare leasing and financing a car over your actual hold period. See which is cheaper after factoring loan interest, monthly cash out, and resale value.
See what salary you need in a target city to maintain the same lifestyle. Weighted by overall and rent indexes from sources like Numbeo.
See how much expense ratios actually cost you over decades. Compare 1% fees vs index fund 0.05% — the gap can exceed your initial investment.
Generate strong random passwords using your browser's secure crypto API. Configurable length, character sets, and ambiguity filter.
Count words, characters, sentences, paragraphs, plus estimated reading and speaking time. Handles CJK languages correctly.
Convert text into 10 case styles: UPPER, lower, Title, Sentence, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, and inverted.
Encode any UTF-8 text to Base64 or decode it back. Toggle URL-safe encoding for use in URLs and JWTs.
Pretty-print or minify JSON. Validates the input and shows a clear error with line and column on failure.
Generate placeholder Latin text by paragraphs, sentences, or word count. Optional 'Lorem ipsum' opening line.
Encode any text into URL percent-encoding or decode an encoded string back. UTF-8 safe — handles emoji and CJK characters correctly.
Convert Arabic numbers to Roman numerals (and back). Validates canonical form so VIIII won't be silently accepted as 9.
Generate cryptographically random UUID v4 or time-ordered UUID v7. Bulk-generate up to 100 at a time with one-click copy.
Compare two blocks of text line by line. Added, removed, and unchanged lines are color-coded with line numbers.
Test JavaScript regular expressions interactively. See live highlighted matches, capture groups, and a replace preview.
Count how often each character or word appears in your text. Sortable, with percentages, and optional case sensitivity.
Compute SHA-1, SHA-256, SHA-384, and SHA-512 hashes of any UTF-8 text. Browser-native Web Crypto API; nothing leaves your device.
Validate email address syntax against RFC 5322 and detect common typos in popular providers (gmail, yahoo, hotmail, etc).
Replace text with literal find/replace or full regex. Toggle case sensitivity and multi-line mode. Match count shown live.
Convert Markdown to clean HTML in your browser. Supports headings, lists, code blocks, links, images, blockquotes, bold/italic/strikethrough.
Convert HTML to Markdown in your browser. Headings, lists, code, links, images, blockquotes, bold/italic/strikethrough.
See your device's browser, OS, screen, hardware, GPU, storage, network, and dark-mode preferences in one place. All detected client-side.
Measure your typing speed in real time. Words per minute (WPM), characters per minute (CPM), accuracy, and elapsed time. Color-coded errors.
Convert any title or sentence into an SEO-friendly URL slug. Configurable separator, length cap, lowercase, and Unicode support.
Calculate network address, broadcast, host range, netmask, wildcard, total/usable hosts from any IPv4 + CIDR. Includes binary representation and class detection.
Test password strength with entropy bits, charset analysis, common-password check, and estimated crack time across attack scenarios.
Encode or decode text with the classic Caesar cipher. Adjustable shift from -25 to +25, with one-click presets for ROT13 and the historical +3 shift.
Decode any JWT (JSON Web Token) into header, payload, signature parts. Highlights expired tokens. Browser-only — your token never leaves your device.
Convert CSV to JSON or JSON to CSV. Configurable delimiter (comma/semicolon/tab/pipe), header-row toggle, RFC 4180 quoted-field handling.
Convert colors between HEX, RGB, and HSL with a live preview swatch. Edit any field; the others update.
Check the color contrast ratio between text and background. Shows live preview and pass/fail badges for WCAG AA and AAA at normal and large text sizes.
Build CSS gradients visually: linear, radial, and conic. Multiple color stops, angle control, presets. Copy ready-to-paste CSS.
Generate harmonious color palettes from a base color: complementary, analogous, triadic, tetradic, monochromatic. Click any swatch to copy hex.
Build CSS box-shadow values visually. Adjust offset, blur, spread, color, opacity, and inset. Live preview, copy-paste CSS.