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Mortgage CalculatorCalculate your monthly mortgage payment: principal and interest, plus property tax, insurance and HOA. See total interest and the full amortization schedule.Percentage CalculatorFree percentage calculator: find what X% of a number is, what percent one number is of another, and percent increase or decrease, with worked examples.BMI CalculatorCalculate your BMI from height and weight in kg/cm or lb/ft. See your WHO weight category and the healthy weight range for your height, formula included.Compound Interest CalculatorCompound interest calculator with monthly contributions and daily to annual compounding. See year-by-year growth, total deposits and interest earned.Age CalculatorCalculate exact age between two dates in years, months and days, plus total months, weeks and days. Works for birthdays, anniversaries and document deadlines.Loan Payment CalculatorCalculate the monthly payment on any amortizing loan — mortgage, car or personal. See total interest over the loan's life and a yearly amortization schedule.GPA CalculatorCalculate your GPA on the standard US 4.0 scale from a list of letter grades and credit hours. Enter A through F, with plus and minus grades supported.Tip CalculatorWork out the tip, the total bill, and each person's share in seconds. Set any tip percentage, split between any number of people, and share the result.
Finance Calculators
Amortization CalculatorSee the full amortization schedule for any fixed-rate loan: monthly detail for year one, then yearly totals, plus payment and total interest.Annuity Payout CalculatorCalculate the monthly payout a balance can sustain for a set number of years, or flip it to see how long a fixed monthly withdrawal will last.APY CalculatorConvert a nominal APR to its effective APY for any compounding frequency, or work backward from APY to APR. See how compounding lifts the effective rate.Biweekly Mortgage CalculatorCompare a standard monthly mortgage against an accelerated biweekly schedule: half payments every two weeks, with payoff time and interest saved.Break-Even Point CalculatorFind the break-even point from fixed costs, price and variable cost per unit: exact and rounded-up units, plus break-even revenue and contribution margin.50/30/20 Budget CalculatorSplit your take-home income into needs, wants, and savings using the 50/30/20 rule or your own custom percentages, plus an actual-vs-target comparison mode.Business Loan CalculatorCalculate a business loan's monthly payment, total interest, total cost including fees, and the effective APR once origination and other fees are factored in.CAGR CalculatorCalculate CAGR, the compound annual growth rate, from a beginning value, ending value, and number of years, plus the total growth percentage.
Health & Fitness Calculators
A1C Calculator (A1C to Average Blood Glucose)Convert A1C to estimated average glucose (eAG) in mg/dL and mmol/L, or the reverse, using the ADAG study formula. Not a substitute for medical advice.Alcohol Unit Calculator (UK)Calculate UK alcohol units from drink volume and ABV, then compare your weekly total to the CMO's 14-unit guideline. Estimates only, not medical advice.BAC CalculatorEstimate blood alcohol concentration with the Widmark formula from sex, weight, drinks, and hours elapsed. Educational only; never drive after drinking.BMI CalculatorCalculate your BMI from height and weight in kg/cm or lb/ft. See your WHO weight category and the healthy weight range for your height, formula included.BMR CalculatorCalculate BMR and total daily energy expenditure with the Mifflin-St Jeor equation. See calorie needs at every activity level, in metric or imperial units.Body Fat CalculatorEstimate body fat percentage from neck, waist and height (plus hip for women) using the U.S. Navy method. See fat mass, lean mass and your ACE category.Body Shape CalculatorEnter bust, waist and hip measurements to find your body-shape category (hourglass, pear, apple or rectangle) and see the bust-to-hip and waist-to-hip ratios.Body Surface Area CalculatorCalculate body surface area (BSA) in square meters using the Mosteller and Du Bois formulas, in metric or imperial units. Formulas and citation included.
Math Calculators
Area CalculatorCalculate area for a rectangle, circle, triangle, or trapezoid. Each shape uses its standard formula, with an exact value of π for circles.Average CalculatorPaste a list of numbers to get the mean, median, mode, range, minimum, maximum, sum, and count in one step. Handles even-count and multi-modal sets.Big Number CalculatorAdd, subtract, multiply, divide, raise to a power, or take the modulo of integers of any size, exact to the last digit, using arbitrary-precision BigInt math.Circle CalculatorEnter a circle's radius, diameter, circumference, or area and get all four measurements instantly. A radius of 5 gives a circumference of 10π ≈ 31.42.Combinations and Permutations CalculatorCalculate nCr combinations, nPr permutations, and n! factorial for any n up to 170. A 5-card hand from a 52-card deck has exactly 2,598,960 combinations.Confidence Interval CalculatorConfidence interval calculator using sample mean, standard deviation and n. Get the margin of error and interval at 90%, 95% or 99% using the z-value.3D Distance CalculatorFind the straight-line distance between two 3D points, plus the midpoint, per-axis deltas, and vector magnitude. Example: (1,2,3) to (4,6,15) is exactly 13.Exponent CalculatorRaise any base to a positive, negative, or fractional exponent. See 2^10 = 1,024 and 9^0.5 = 3, with large or tiny results shown in scientific notation.
Unit Converters
Angle ConverterConvert angles between degrees, radians, gradians, arcminutes, arcseconds and turns. A full circle is 360°, 2π rad, 400 grad or 1 turn.Area ConverterConvert area between square millimeters, meters, hectares, acres, square feet, yards and miles using exact international definitions, with the factor shown.Blood Sugar Converter (mg/dL to mmol/L)Convert blood glucose between mg/dL and mmol/L with the exact 18.0182 factor. See a reference table of common values. General reference, not a diagnosis.Clothing Size ConverterConvert women's, men's shirt, and trouser sizes between US, UK, EU, and international S-M-L, with the published body measurements behind each size.Cooking Measurement ConverterConvert cooking volumes between US teaspoons, tablespoons, cups, pints, quarts, gallons, milliliters, liters and metric spoons. Volume only, not weight.Data Storage ConverterConvert data storage between bits, bytes, decimal units (KB/MB/GB/TB) and binary units (KiB/MiB/GiB/TiB), explaining why drives 'lose' capacity.Energy ConverterConvert energy between joules, kilojoules, megajoules, calories, kilocalories, watt-hours, kilowatt-hours and BTU using exact defined constants.Fuel Economy ConverterConvert fuel economy between mpg (US), mpg (Imperial/UK), km/L and L/100km. Handles the reciprocal relationship of L/100km correctly in both directions.
Date & Time Calculators
Age CalculatorCalculate exact age between two dates in years, months and days, plus total months, weeks and days. Works for birthdays, anniversaries and document deadlines.Business Days CalculatorCount the Monday-to-Friday business days between two dates, including or excluding the end date. Public holidays are not subtracted automatically.Conception Date CalculatorEstimate a likely conception date and window from a due date or a birth date, using the standard 266-day conception-to-birth convention.Date Calculator (Add or Subtract)Add or subtract days, weeks, months or years from any date and get the resulting weekday and full date, with correct month-end clamping.Date Difference CalculatorFind the exact difference between two dates in years, months and days, plus totals in days, weeks and months. Works with dates entered in either order.Day of the Week CalculatorFind the day of the week for any date, past or future, plus its day-of-year number, days in that year, and whether it is a leap year.Days Until CalculatorCalculate how many days, weeks and days remain until any target date, or how many days have passed if that date is already behind you.Pregnancy Due Date CalculatorEstimate your pregnancy due date from your last period and cycle length using Naegele's rule, plus your current gestational week and trimester.
Everyday Calculators
Discount CalculatorCalculate the sale price after one or two stacked discounts, the amount saved, and the true effective discount rate — 20% plus 10% is 28%, not 30%.Stacked Discount CalculatorStack up to four discounts, a flat coupon, and sales tax to see the final price, total saved, and the true effective discount percentage.Electricity Cost CalculatorFind out how many kWh an appliance uses and what it costs per day, month and year from its wattage, daily hours of use, and your price per kWh.Final Grade CalculatorFind the score you need on your final exam to reach a target course grade, given your current grade and how much the final is worth.Fuel Cost CalculatorEstimate how much fuel a trip will use and cost from distance, fuel economy and the price at the pump, in US units (mpg, gallons) or metric (L/100km, liters).Golf Handicap CalculatorCalculate your USGA/R&A World Handicap System Handicap Index from score differentials or raw scores, using the official best-8-of-20 averaging table.Mulch CalculatorFind out how much mulch a garden bed needs in cubic yards or cubic meters from its area and depth, plus how many 2 cubic foot bags to buy.Paint CalculatorWork out paintable wall area from room dimensions, doors and windows, then how many liters or gallons of paint to buy, rounded up to a whole can.
Home & Garden Calculators
Concrete CalculatorConcrete calculator for slabs, footings and round columns. Get cubic yards or meters plus 60 lb and 80 lb bag counts, rounded up so you never come up short.Deck CalculatorPlan a deck build: enter length, width, board size and joist spacing to get square footage, deck boards, joists, beam lines, posts and a rough fastener count.Drywall CalculatorWork out drywall sheets, screws, joint compound and joint tape for a room from its dimensions, doors and windows, and sheet size, with 10% waste built in.Fence CalculatorFind how many fence posts, pickets and horizontal rails a fence needs from its length, post spacing and picket size, including the classic fencepost count.Grass Seed CalculatorFind how much grass seed a new lawn or overseeding job needs from its area and grass type, using published university extension seeding rate ranges.Gravel CalculatorWork out how much gravel a driveway or path needs in cubic yards or meters and tons, from area and depth. Adjust the density field for your specific material.BTU Calculator (AC & Heating Sizing)Estimate cooling and heating BTU/hr from room area, ceiling height, sun exposure, room type and occupants, using a published ~20 BTU per sq ft rule of thumb.Board Foot CalculatorCalculate board feet from thickness, width and length in quarters or inches, then multiply by quantity and price per board foot for a total lumber cost.
Tech & Web Calculators
Aspect Ratio CalculatorSimplify any width and height to its lowest-terms aspect ratio, or enter a ratio and a new width to solve for the matching height. Common ratios included.Bandwidth CalculatorWork out required network bandwidth for concurrent users or video streams, and estimate monthly data usage from your daily viewing hours.Binary CalculatorBinary calculator that converts between decimal, binary, octal and hexadecimal at once. Decimal 42 equals binary 101010, octal 52 and hex 2A.Color Contrast Checker (WCAG)Check the WCAG 2.1 contrast ratio between a foreground and background hex color, with instant AA and AAA pass/fail results for text and UI components.Download Time CalculatorWork out download time from file size and connection speed. Handles the Mbps-vs-MB/s bits-to-bytes conversion automatically, with a realistic-speed estimate.Hex to RGB ConverterConvert a hex color code to its RGB and HSL values, or enter RGB numbers to get the matching hex code. Supports both #RRGGBB and shorthand #RGB formats.Megapixel CalculatorConvert pixel dimensions to megapixels and aspect ratio, or solve megapixels + ratio back to width and height. Includes max print size at any DPI.Password Entropy CalculatorEstimate a password's entropy in bits from its length and character set, with illustrative brute-force crack times. For randomly generated passwords only.
Fun Calculators
Cat Age CalculatorConvert your cat's age to human years using the common veterinary rule of thumb: 15 for year one, +9 for year two, then +4 per year after.Dog Age CalculatorConvert your dog's age to human years with the common veterinary rule of thumb: 15 for year one, +9 for year two, then a size-based rate per year.Love CalculatorEnter two names for a fun, deterministic love match percentage. Same names always give the same score — purely for entertainment, no science involved.Movie Marathon CalculatorAdd up a list of film runtimes plus breaks between them to see total watch time, total time including breaks, and your finish time if you start now.