TopTool

Category

Calculators

Everyday calculators — BMI, percentage, age, tip, date diff.

35 free calculators tools — no sign-up, runs in your browser.

CalculatorsCalculator

BMI Calculator

Compute Body Mass Index from height and weight in either metric or imperial units.

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CalculatorsCalculator

Percentage Calculator

Compute percent of a number, the percentage one number is of another, and percentage change.

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CalculatorsCalculator

Age Calculator

Compute your age in years, months, and days from a date of birth — plus total days lived.

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CalculatorsCalculator

Date Difference Calculator

Compute the difference between two dates in years, months, days, hours, minutes, seconds.

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CalculatorsCalculator

Tip Calculator

Calculate tip and split a restaurant bill across any number of people.

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CalculatorsConverter

Timezone Converter

Convert a time from any timezone to any other — Central to Pacific, UTC to Tokyo, you name it.

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CalculatorsCalculator

Aspect Ratio Calculator

Compute aspect ratios and resize dimensions while preserving the original proportion — 16:9, 4:3, 21:9 and more.

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CalculatorsConverter

Bytes Converter

Convert between bytes, KB, MB, GB, TB and their binary counterparts KiB, MiB, GiB, TiB.

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CalculatorsConverter

Length Converter

Convert between metric and imperial length units — mm, cm, m, km, inches, feet, yards, miles.

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CalculatorsConverter

Weight Converter

Convert between metric and imperial weight units — mg, g, kg, tonnes, ounces, pounds, stone, US tons.

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CalculatorsConverter

Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin and Rankine using the exact formulas, not approximations.

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CalculatorsConverter

Speed Converter

Convert between m/s, km/h, mph, knots and ft/s — covers driving, flying, sailing and physics units.

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CalculatorsConverter

Volume Converter

Convert between mL, L, cubic meters, US fluid ounces, cups, pints, quarts, and gallons (US + Imperial).

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CalculatorsRandom

Coin Flip

Flip a virtual coin once or hundreds of times — cryptographically random, fair 50/50 odds.

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CalculatorsRandom

Dice Roller

Roll d4, d6, d8, d10, d12, d20 or d100 dice — D&D notation like 3d6+2 supported via the modifier field.

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CalculatorsRandom

Random Picker

Pick random items from a list — names, options, prizes. Cryptographically fair, with or without duplicates.

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CalculatorsCalculator

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.

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CalculatorsCalculator

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.

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CalculatorsCalculator

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.

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CalculatorsCalculator

Scientific Calculator

Evaluate math expressions with trig, logs, roots and constants — degrees or radians, all in your browser.

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CalculatorsCalculator

Compound Interest Calculator

Project savings/investment growth with compound interest — set principal, annual rate, years, compounding frequency and optional monthly contribution.

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CalculatorsCalculator

Loan & Mortgage Calculator

Compute monthly payment, total interest, and the amortization schedule for any fixed-rate loan or mortgage.

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CalculatorsCalculator

Discount Calculator

Compute the sale price after a percent discount — supports stacked discounts and an optional sales-tax / VAT addition.

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CalculatorsCalculator

Salary Converter

Convert between hourly, daily, weekly, biweekly, monthly and annual salary — adjust hours/week and weeks/year.

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CalculatorsCalculator

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.

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CalculatorsPlanner

Time Zone Meeting Planner

Find overlapping working hours across two time zones to schedule meetings — free, runs in your browser.

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CalculatorsCalculator

Electricity Cost Calculator

Calculate your electricity cost from watts, usage hours and rate per kWh — see daily, monthly and yearly estimates instantly.

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CalculatorsCalculator

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.

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CalculatorsCalculator

GPA Calculator

Calculate your GPA from letter grades and credit hours — supports A+ through F on the standard 4.0 scale.

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CalculatorsConverter

Number to Words Converter

Convert any number to English words — supports up to trillions, decimals, negatives, and ordinals.

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CalculatorsConverter

Roman Numeral Converter

Convert between Roman numerals and integers — validates input and handles values from 1 to 3,999.

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CalculatorsConverter

Scientific Notation Converter

Convert between standard numbers and scientific notation — see mantissa, exponent, and both forms instantly.

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CalculatorsValidator

IMEI Validator

Validate a 15-digit IMEI with the Luhn check digit and extract the TAC, serial number, and reporting body prefix.

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CalculatorsGenerator

IMEI Generator

Generate valid-format test IMEI numbers with correct Luhn check digits for QA, forms, and modem calculator testing.

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CalculatorsCalculator

Huawei Unlock Code Calculator

Calculate Huawei modem NCK unlock codes for v1, v2, and v201 algorithms, plus the flash code, from a valid IMEI.

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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.