Free Online Calculators
Practical everyday calculators for finance, health, dates, and quick math. All run in your browser — no sign-up required.
Most Popular
Our highest-traffic calculators.
Mortgage Calculator
Calculate monthly payment, total interest, and amortization from home price, rate, and term.
🏖️Retirement Calculator
Project retirement savings balance from contributions, return rate, and employer match.
📈Compound Interest Calculator
Calculate future investment value with custom principal, rate, time, and compounding frequency.
📊CAGR Calculator
Calculate Compound Annual Growth Rate from beginning and ending investment values.
🌍Time Zone Converter
Convert any time between Eastern, Central, Mountain, Pacific, UTC, London, Paris, Tokyo, and Sydney.
⚖️BMI Calculator
Calculate Body Mass Index in metric or imperial. Includes BMI category reference table.
💼Hourly to Salary Calculator
Convert an hourly wage to annual, monthly, and weekly pay — or a salary back to an hourly rate.
🎓GPA Calculator
Semester GPA from course credits and letter grades on the 4.0 scale, plus cumulative GPA.
🛍️Discount Calculator
Sale price after any percent off — including stacked extra discounts — or find the discount %.
📆Date Calculator
Add or subtract days, weeks, months, or years from any date — what is 30/60/90 days from today.
🕐Time Card Calculator
Weekly work hours from clock-in/out times with breaks, overtime, and gross pay.
🚗Auto Loan Calculator
Monthly car payment from price, down payment, trade-in, sales tax, APR, and term.
📝Word Counter
Count words, characters, sentences, and paragraphs with reading and speaking time estimates.
🔐Password Generator
Generate strong random passwords locally with entropy bits and crack-time estimates.
🔢Random Number Generator
Generate random numbers in any range with crypto-grade randomness, with or without repeats.
➗Fraction Calculator
Add, subtract, multiply, and divide fractions with steps, simplified results, and mixed numbers.
🌈Color Converter
Convert colors between HEX, RGB, and HSL with a live swatch preview and copy-ready CSS values.
📟Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back, with the live epoch time in seconds.
🌐Subnet Calculator
Find network and broadcast addresses, usable host ranges, and masks for any IPv4 CIDR prefix.
ΩOhm's Law Calculator
Enter any two of voltage, current, resistance, and power — the other two are computed instantly.
🔌Voltage Drop Calculator
Voltage drop by wire gauge, length, and load — with the NEC 3% check and the gauge that passes.
🏋️One Rep Max Calculator
Estimate your 1RM from any set with four formulas, plus a training-percentage chart.
💹Margin & Markup Calculator
Margin, markup, price, and profit from any two inputs — and the difference between the two percentages.
🐕Dog Age Calculator
Dog years to human years with the 2020 epigenetic formula, the vet size table, and the ×7 myth.
💰 Finance
Mortgage Calculator
Calculate monthly payment, total interest, and amortization from home price, rate, and term.
🏖️Retirement Calculator
Project retirement savings balance from contributions, return rate, and employer match.
📈Compound Interest Calculator
Calculate future investment value with custom principal, rate, time, and compounding frequency.
💰Savings Calculator
Project savings growth with starting balance, monthly contributions, and interest rate.
🏦Loan Calculator
Calculate monthly payment, total repayment, and total interest for any loan.
📋Amortization Schedule
Full payment-by-payment principal and interest breakdown for any loan.
📊CAGR Calculator
Calculate Compound Annual Growth Rate from beginning and ending investment values.
📉Inflation Calculator
Calculate how inflation erodes purchasing power and find inflation-adjusted values.
💼Hourly to Salary Calculator
Convert an hourly wage to annual, monthly, and weekly pay — or a salary back to an hourly rate.
🧾Sales Tax Calculator
Add sales tax to a price, or back the tax out of a receipt total, with common rate presets.
🚗Auto Loan Calculator
Monthly car payment from price, down payment, trade-in, sales tax, APR, and term.
💳Credit Card Payoff Calculator
Months to pay off a balance and total interest — or the payment that hits a target date.
💹Margin & Markup Calculator
Margin, markup, price, and profit from any two inputs — and the difference between the two percentages.
🏁Break-Even Calculator
Units and revenue needed to break even from fixed costs, price, and variable cost per unit.
📅 Date & Time
Age Calculator
Calculate exact age in years, months, and days from any date of birth.
📅Date Difference Calculator
Find the exact difference between two dates in days, weeks, months, and years.
💼Business Days Calculator
Count working days between two dates, excluding weekends.
⏳Countdown Calculator
Count down to any future date in days, weeks, months, and years.
🌍Time Zone Converter
Convert any time between Eastern, Central, Mountain, Pacific, UTC, London, Paris, Tokyo, and Sydney.
⏱️Time Duration Calculator
Add or subtract hours, minutes, and seconds from any start time.
📆Date Calculator
Add or subtract days, weeks, months, or years from any date — what is 30/60/90 days from today.
🕐Time Card Calculator
Weekly work hours from clock-in/out times with breaks, overtime, and gross pay.
🏃 Health & Fitness
BMI Calculator
Calculate Body Mass Index in metric or imperial. Includes BMI category reference table.
🍎Calorie Calculator
Estimate daily calorie needs using the Mifflin-St Jeor equation (BMR & TDEE).
😴Sleep Calculator
Find optimal bedtime or wake-up time based on 90-minute sleep cycles.
🏃Running Pace Calculator
Pace per mile and per km from any distance and finish time, with 5K to marathon presets.
📏Body Fat Calculator
Body fat percentage from tape measurements using the US Navy method, with ACE categories.
🎯Ideal Weight Calculator
Ideal body weight from Devine, Robinson, Miller, and Hamwi formulas plus the healthy BMI range.
🥗Macro Calculator
Daily protein, carbs, and fat in grams from your TDEE, goal, and preferred macro split.
🔥BMR Calculator
Basal metabolic rate from three equations side by side, plus TDEE at every activity level.
🏋️One Rep Max Calculator
Estimate your 1RM from any set with four formulas, plus a training-percentage chart.
❤️Heart Rate Zone Calculator
Five training zones from your age — Tanaka max HR, plus the Karvonen method with resting HR.
🧮 Everyday Math
Percentage Calculator
Find X% of Y, what percent X is of Y, and percentage change or increase.
🍽️Tip Calculator
Calculate tip amount, total bill, and per-person split instantly.
🏷️Unit Price Calculator
Compare price per unit of two products to instantly find the best value.
⚡Watts to Amps Calculator
Convert watts to amps (or amps to watts) at 120 V, 240 V, or any voltage, with circuit-load warnings.
💡Electricity Cost Calculator
What any appliance costs to run per day, month, and year from its wattage and your electricity rate.
⛽Fuel Cost Calculator
Trip gas cost from distance, your car's MPG, and the price per gallon, with vehicle presets.
⬇️Download Time Calculator
How long a file takes to download from its size and your connection speed in Mbps.
🔋Battery Life Calculator
Estimate battery runtime from mAh capacity and device current draw, with an efficiency factor.
📺TV Viewing Distance Calculator
Ideal seating distance for any TV size, for 4K and 1080p, plus real screen dimensions.
🎓GPA Calculator
Semester GPA from course credits and letter grades on the 4.0 scale, plus cumulative GPA.
📝Final Grade Calculator
The exact score you need on the final exam to hit your target course grade.
📐Square Footage Calculator
Area of rooms and odd shapes in sq ft, yards, and meters, with waste and flooring cost.
🎨Paint Calculator
Gallons of paint needed for a room from its dimensions, doors, windows, and coats.
🧱Concrete Calculator
Cubic yards and premix bags for slabs, footings, and columns, with 10% waste built in.
🛍️Discount Calculator
Sale price after any percent off — including stacked extra discounts — or find the discount %.
🔤Number to Words Converter
Spell out any number in words, including the check-writing dollar format.
🖼️Aspect Ratio Calculator
Find the aspect ratio of any resolution, or solve the missing width or height.
❄️BTU Calculator
AC sizing in BTUs and tons from room square footage, insulation, sun, and occupancy.
🏚️Roofing Calculator
Roof area, roofing squares, and shingle bundles from footprint and pitch.
🪜Stair Calculator
Risers, treads, total run, and stringer length from total rise, with IRC code checks.
🍟Air Fryer Converter
Convert oven recipes to air fryer settings — temperature −25°F, time −20%.
🥣Recipe Scaler
Resize any recipe to your serving count — handles fractions and kitchen-friendly rounding.
🥶Wind Chill Calculator
Feels-like temperature from cold and wind using the official NWS formula, with frostbite risk.
🥵Heat Index Calculator
Feels-like temperature from heat and humidity using the official NWS formula, with risk levels.
🏛️Roman Numeral Converter
Numbers to Roman numerals and back, 1–3999, with strict-form validation.
🪞Tile Calculator
Tiles and boxes needed for any floor or wall, from room size, tile size, and waste.
🌳Mulch Calculator
Cubic yards and bags of mulch from bed dimensions and depth, with coverage reference.
🪨Gravel Calculator
Cubic yards and tons of gravel, stone, sand, or topsoil from area, depth, and material.
➗Fraction Calculator
Add, subtract, multiply, and divide fractions with steps, simplified results, and mixed numbers.
🧮Mean, Median, Mode Calculator
Find the mean, median, mode, range, sum, min, and max of any list of numbers instantly.
σStandard Deviation Calculator
Calculate sample and population standard deviation with mean, variance, and steps shown.
🧩GCF & LCM Calculator
Find the greatest common factor and least common multiple of 2–10 numbers, with prime factorizations.
x²Quadratic Formula Calculator
Solve ax² + bx + c = 0 — real or complex roots, discriminant, vertex, and axis of symmetry with steps.
∷Ratio Calculator
Simplify any ratio to lowest terms or solve a proportion for the missing value with steps.
🪵Deck Calculator
Decking boards, screws, and joists from deck size, board width, gap, and waste factor.
🚧Fence Calculator
Posts, rails, pickets, and concrete bags from fence length, post spacing, and style.
🔲Drywall Calculator
Sheets, joint compound, tape, and screws for a room, with door and window deductions.
🌱Topsoil Calculator
Cubic yards, 40-lb bags, and tons of topsoil from area and depth, with lawn and bed presets.
🏊Pool Volume Calculator
Gallons, liters, and cubic meters for rectangular, round, and oval pools using industry formulas.
ΩOhm's Law Calculator
Enter any two of voltage, current, resistance, and power — the other two are computed instantly.
🔌Voltage Drop Calculator
Voltage drop by wire gauge, length, and load — with the NEC 3% check and the gauge that passes.
🚙MPG Calculator
Real-world gas mileage from odometer readings or trip miles — with L/100 km and cost per mile.
🧭DMS to Decimal Degrees Converter
Convert GPS coordinates between degrees-minutes-seconds and decimal degrees, both directions.
☕Coffee Ratio Calculator
Grams of coffee for your water — or water for your coffee — for drip, French press, espresso, and more.
🍰Baking Pan Converter
Swap pan sizes without ruining the recipe — exact ingredient multiplier from pan areas.
🦃Turkey Cooking Time Calculator
Roast time at 325°F for any turkey weight, stuffed or unstuffed, plus thawing times — per the USDA table.
🐕Dog Age Calculator
Dog years to human years with the 2020 epigenetic formula, the vet size table, and the ×7 myth.
📝 Text & Random
Word Counter
Count words, characters, sentences, and paragraphs with reading and speaking time estimates.
🔐Password Generator
Generate strong random passwords locally with entropy bits and crack-time estimates.
🔢Random Number Generator
Generate random numbers in any range with crypto-grade randomness, with or without repeats.
🎲Dice Roller
Roll d4 through d100 dice with modifiers and see totals and roll history.
🪙Coin Flip
Flip up to 100 virtual coins with a running heads and tails tally.
💻 Developer Tools
Number Base Converter
Convert between decimal, binary, hexadecimal, and octal — handles huge numbers.
🌈Color Converter
Convert colors between HEX, RGB, and HSL with a live swatch preview and copy-ready CSS values.
📟Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back, with the live epoch time in seconds.
🔣Base64 Encoder & Decoder
Encode and decode Base64 instantly — UTF-8 safe, with a URL-safe variant for tokens and JWTs.
🌐Subnet Calculator
Find network and broadcast addresses, usable host ranges, and masks for any IPv4 CIDR prefix.
🔍PPI Calculator
Calculate pixels per inch, dot pitch, and total megapixels from resolution and screen size.
AaPX to REM Converter
Convert px to rem, em, pt, and percent at any root font size — with a common-sizes cheat sheet.
Every calculator runs entirely in your browser — no data is sent to any server. Looking for unit converters instead?
Reference Libraries
Bookmark these reference tables for quick lookup alongside your calculations.
Finance Reference
Tax brackets, 401(k) limits, IRA limits, HSA limits, inflation history.
📅Date & Time Reference
Federal holidays, week numbers, day of year, calendar reference.
📐Measurement Reference
Metric prefixes, paper sizes, wire gauge, drill bits.
🖨️Printable Charts
Print-ready conversion and metric charts.