Percentage Calculator
Solve common percentage calculations instantly — what is X% of Y, percentage change, and reverse percent.
Calculators & Converters20 live toolsFree onlineNo sign-up
Free Online Calculators & Converters — No Sign-Up Required
Everyday calculators for finance, health, dates, units, fuel, electricity, and quick conversions.
Most everyday calculations don't need a spreadsheet — they need a single field, an instant answer, and no formula to remember. Our free online calculators and converters do exactly that, entirely in your browser, with no account and no data leaving your device. The collection spans unit conversion (length, weight, temperature, volume, speed, and data storage), percentage and ratio maths, date and time arithmetic, number-base conversion (binary, octal, hexadecimal, decimal), and a range of health, finance, and everyday calculators. Each tool shows its working where it matters, handles edge cases like leap years and rounding correctly, and updates the result as you type. Whether you are converting a recipe from cups to millilitres, working out the number of business days between two dates, or checking a percentage discount, the answer appears immediately.
GPA Calculator
Estimate GPA from course grades and credit hours — supports 4.0 and weighted grading systems.
Age Calculator
Calculate exact age from a birth date with years, months, and days — find how many days until your birthday.
Date Difference Calculator
Measure the exact duration between two dates and times — calculate days, weeks, months, and hours between dates.
Loan Calculator
Estimate monthly EMI payments, total interest cost, and full repayment schedule for any loan.
BMI Calculator
Calculate body mass index from weight and height — includes BMI category classification and health guidance.
Unit Converter
Convert between common units for length, weight, speed, and temperature — instant multi-unit calculator.
Currency Converter
Convert currencies with live exchange rates plus offline fallback — support for 150+ world currencies.
Time Zone Converter
Convert a date and time across major world time zones — plan meetings across countries instantly.
Roman Numeral Converter
Convert numbers to Roman numerals and vice versa — supports I to MMMCMXCIX with instant conversion.
Tip Calculator
Calculate tip amount, total bill, and per-person split in one step — the easiest restaurant tip calculator.
Discount Calculator
Work out discount savings and final price after percentage reductions — calculate sale prices instantly.
Percentage Change Calculator
Measure percentage increase or decrease between two values — essential for financial and analytics reporting.
Markup Calculator
Calculate selling price and profit from cost and markup percentage — retail pricing made simple.
Margin Calculator
Estimate gross margin percentage and net profit from selling price and cost — essential for pricing decisions.
Fuel Cost Calculator
Estimate fuel needed and trip cost from distance, efficiency, and fuel price — plan road trips easily.
Electricity Cost Calculator
Estimate monthly electricity cost from wattage, daily runtime, and energy price — reduce your power bill.
Pace Calculator
Calculate running pace per kilometer and average speed from distance and total time — runner's must-have tool.
Compound Interest Calculator
Estimate future value and earned interest with annual compound growth — investment and savings planning tool.
Speed Distance Time Calculator
Calculate speed, distance, or time from any two known values — physics and travel planning formula tool.
What can you do with free calculators & converters tools?
Students and homework
Convert units for physics and chemistry problems, calculate percentages and averages, and switch between number bases for computer-science coursework. The calculators show the conversion factor used so you can verify the method, not just copy the answer.
Everyday life and home
Convert cooking measurements between metric and imperial, work out tip and discount amounts, calculate how many days until an event, and convert temperatures for travel. Date-difference calculations correctly account for leap years and varying month lengths.
Developers and technical users
Convert between binary, octal, hexadecimal, and decimal for bit-level work, calculate data-storage sizes (KB, MB, GB with both 1000 and 1024 bases), and convert Unix timestamps to human-readable dates. These avoid the off-by-one errors common when doing base conversions by hand.
Finance and budgeting
Calculate percentage change for price comparisons, work out compound versus simple interest, and convert currencies using current rates. Percentage-increase and percentage-of calculations are separated so you don't confuse 'X is what percent of Y' with 'increase X by Y percent'.
Calculators & Converters tools — frequently asked questions
Do these calculators use 1000 or 1024 for data sizes?
The data-storage converter supports both. The decimal (SI) standard uses 1000 (1 KB = 1000 bytes), which is how storage manufacturers label drives. The binary standard uses 1024 (1 KiB = 1024 bytes), which is how operating systems report file sizes. The tool labels each clearly so you pick the right one.
Are date calculations adjusted for leap years?
Yes. The date-difference calculator uses real calendar arithmetic, so it correctly counts leap days (February 29) and handles months of different lengths. A range crossing February in a leap year will include the extra day; the same range in a non-leap year will not.
How accurate are the unit conversions?
Conversions use internationally defined exact factors where they exist (for example, 1 inch = 2.54 cm exactly, 1 pound = 0.45359237 kg exactly). Results are shown to a sensible number of decimal places, and you can see the underlying factor for verification.
Is there a difference between percentage increase and percentage of?
Yes, and confusing them is a common mistake. 'What is 20% of 150' equals 30. 'Increase 150 by 20%' equals 180. 'What percent of 150 is 30' equals 20%. The calculators keep these as separate inputs so you always get the calculation you intended.
Can I convert temperatures including Kelvin?
Yes. The temperature converter handles Celsius, Fahrenheit, and Kelvin in any direction. Note that Kelvin has no negative values (absolute zero is 0 K = -273.15°C), and the tool reflects that physical constraint.
Do the calculators work offline?
All calculations run client-side in JavaScript, so unit, percentage, date, and number-base calculators work fully offline after the page loads. Currency conversion is the exception — it needs a network request to fetch up-to-date exchange rates.
Curated calculators & converters tool collections
Hand-picked sets of free tools and guides related to calculators & converters.
Free AI Productivity Tools — Automate Your Daily WorkflowsDiscover free AI productivity tools in 2026 that automate writing, formatting, data processing, and content creation workflows — no account, browser-based.Free Calculator Tools Online — Calculate Anything in BrowserUse free calculator tools online in 2026: percentage calculators, unit converters, currency converters, date difference calculators, BMI calculators, loan calculators, and more — no signup, instant results.Free Finance Calculator Tools Online — Plan, Budget & ProfitUse free finance calculator tools online in 2026: profit margin calculators, break-even calculators, SaaS pricing calculators, sales tax tools, invoice late fee calculators, and subscription revenue forecasters — no account needed.Free Engineering Calculator Tools Online — Electronics & Applied MathUse free engineering calculator tools online in 2026: voltage divider calculators, LED resistor calculators, Ohm's law tools, capacitor calculators, resistor color code decoders, and math tools — no account needed.Free Astronomy Tools Online — Explore Space with Browser-Based CalculatorsUse free astronomy tools online in 2026: moon phase finders, planet weight calculators, escape velocity tools, telescope magnification comparators, and field of view calculators — no account needed.Free Education Tools Online — Study Smarter, Learn FasterDiscover free online education tools in 2026: study session planners, flashcard randomizers, GPA calculators, typing practice tools, free book access, word counters, and readability checkers — no account needed.
Explore more free tools
224+ browser-based tools across 13 categories — all free, no sign-up required.