Category
Calculators
Everyday calculators — BMI, percentage, age, tip, date diff.
34 free calculators tools — no sign-up, runs in your browser.
BMI Calculator
Compute Body Mass Index from height and weight in either metric or imperial units.
Open tool →Percentage Calculator
Compute percent of a number, the percentage one number is of another, and percentage change.
Open tool →Age Calculator
Compute your age in years, months, and days from a date of birth — plus total days lived.
Open tool →Date Difference Calculator
Compute the difference between two dates in years, months, days, hours, minutes, seconds.
Open tool →Tip Calculator
Calculate tip and split a restaurant bill across any number of people.
Open tool →Timezone Converter
Convert a time from any timezone to any other — Central to Pacific, UTC to Tokyo, you name it.
Open tool →Aspect Ratio Calculator
Compute aspect ratios and resize dimensions while preserving the original proportion — 16:9, 4:3, 21:9 and more.
Open tool →Bytes Converter
Convert between bytes, KB, MB, GB, TB and their binary counterparts KiB, MiB, GiB, TiB.
Open tool →Length Converter
Convert between metric and imperial length units — mm, cm, m, km, inches, feet, yards, miles.
Open tool →Weight Converter
Convert between metric and imperial weight units — mg, g, kg, tonnes, ounces, pounds, stone, US tons.
Open tool →Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin and Rankine using the exact formulas, not approximations.
Open tool →Speed Converter
Convert between m/s, km/h, mph, knots and ft/s — covers driving, flying, sailing and physics units.
Open tool →Volume Converter
Convert between mL, L, cubic meters, US fluid ounces, cups, pints, quarts, and gallons (US + Imperial).
Open tool →Coin Flip
Flip a virtual coin once or hundreds of times — cryptographically random, fair 50/50 odds.
Open tool →Dice Roller
Roll d4, d6, d8, d10, d12, d20 or d100 dice — D&D notation like 3d6+2 supported via the modifier field.
Open tool →Random Picker
Pick random items from a list — names, options, prizes. Cryptographically fair, with or without duplicates.
Open tool →Stopwatch (Duration Calculator)
Format, add, or subtract durations like '1:23:45' or '1h 30m'. Heads up — this is a calculator, not a live stopwatch.
Open tool →Countdown Timer (Time Until)
Calculate how much time until a date — days, hours, minutes, seconds. Heads up: it's a calculator, not a live ticking countdown.
Open tool →Pomodoro Timer (Schedule Calculator)
Plan a pomodoro study session — how many cycles, work + break minutes, total time. It's a planner, not a ticking timer.
Open tool →Compound Interest Calculator
Project savings/investment growth with compound interest — set principal, annual rate, years, compounding frequency and optional monthly contribution.
Open tool →Loan & Mortgage Calculator
Compute monthly payment, total interest, and the amortization schedule for any fixed-rate loan or mortgage.
Open tool →Discount Calculator
Compute the sale price after a percent discount — supports stacked discounts and an optional sales-tax / VAT addition.
Open tool →Salary Converter
Convert between hourly, daily, weekly, biweekly, monthly and annual salary — adjust hours/week and weeks/year.
Open tool →VAT / Sales Tax Calculator
Add VAT/sales tax to a net amount, or extract VAT from a gross amount — also derives the tax portion as a standalone figure.
Open tool →Time Zone Meeting Planner
Find overlapping working hours across two time zones to schedule meetings — free, runs in your browser.
Open tool →Electricity Cost Calculator
Calculate your electricity cost from watts, usage hours and rate per kWh — see daily, monthly and yearly estimates instantly.
Open tool →Fuel Cost Calculator
Calculate the fuel cost for any trip — enter distance, fuel efficiency and price per gallon or liter to see total cost and fuel needed.
Open tool →GPA Calculator
Calculate your GPA from letter grades and credit hours — supports A+ through F on the standard 4.0 scale.
Open tool →Number to Words Converter
Convert any number to English words — supports up to trillions, decimals, negatives, and ordinals.
Open tool →Roman Numeral Converter
Convert between Roman numerals and integers — validates input and handles values from 1 to 3,999.
Open tool →Scientific Notation Converter
Convert between standard numbers and scientific notation — see mantissa, exponent, and both forms instantly.
Open tool →IMEI Validator
Validate a 15-digit IMEI with the Luhn check digit and extract the TAC, serial number, and reporting body prefix.
Open tool →IMEI Generator
Generate valid-format test IMEI numbers with correct Luhn check digits for QA, forms, and modem calculator testing.
Open tool →Huawei Unlock Code Calculator
Calculate Huawei modem NCK unlock codes for v1, v2, and v201 algorithms, plus the flash code, from a valid IMEI.
Open tool →Frequently asked
Are TopTool calculators free?
Yes. BMI, percentage, age, tip, date-difference and all other calculators are free and unlimited.
Are calculations done locally?
Yes. Calculators run in your browser. No input is sent to any server.
Can I use the calculators offline?
Yes. Once the page is loaded, calculators work without an internet connection.