Free calculators, converters and online tools

Calculate an answer, convert a unit, write a note or preview HTML. Mathmatives brings practical tools together with examples and clear limits, without an account.

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Popular calculators

Math Calculators

Basic Calculator: Everyday arithmetic with keyboard input and history.
Scientific Calculator: Trig, logs, powers, factorials, memory and history.
Percentage Calculator: Five quick percentage tools, answered as you type.
Fraction Calculator: Add, simplify or convert fractions as you type.
Average Calculator: Mean, median, mode and more, live as you type.
Attendance Calculator: Calculate attendance percentage, classes needed for your target and recovery before the term ends. Supports separate subjects and optional remaining classes.

Unit Converters

Time Zone Converter: Convert between any two zones, DST included.
EST to IST Converter: Plan calls from New York to India using the event date, daylight-saving offsets and day changes.
IST to EST Converter: Plan calls from India to New York using the event date, daylight-saving offsets and day changes.
PST to IST Converter: Plan calls from Los Angeles to India using the event date, daylight-saving offsets and day changes.
CST to IST Converter: Plan calls from Chicago to India using the event date, daylight-saving offsets and day changes.
BST to IST Converter: Plan calls from London to India using the event date, daylight-saving offsets and day changes.
GMT to IST Converter: Plan calls from GMT to India using the event date, daylight-saving offsets and day changes.
Unit Converter: Every everyday unit in one tool, with the formula shown.
Length Converter: mm, cm, m, km, inches, feet, yards, miles and gaj.
Weight Converter: kg, grams, pounds, ounces, stone, tons and newtons.
Volume Converter: Liters, mL, gallons, cups, fluid ounces and more.
Speed Converter: mph, km/h, m/s, knots and running pace.
Time Converter: Seconds, minutes, hours, days, weeks, months and years.
Temperature Converter: Celsius, Fahrenheit and Kelvin with the formulas.
Area Converter: sq ft, sq m, acres, hectares, gaj, cent and more.
Data Storage Converter: Bytes, KB, MB, GB, TB and the binary units.
Pressure Converter: psi, bar, kPa, atm, mmHg and kgf/cm².
Fuel Economy Converter: mpg (US and UK), L/100 km and km/L.
Energy Converter: Calories, kJ, joules, kWh and BTU.
Height Converter (Feet, Inches to cm): 5 ft 8 in to cm and back, with a height chart.
Kg to Liter Converter: 1 kg of water = 1 L. Other liquids by density.
Binary to Text Translator: Translate binary bytes to text or encode text as UTF-8 binary.
All 69 converters: 47 more dedicated pages, such as miles to km, kg to lbs and gallons to liters.

Salary & Employment

Salary to Hourly Calculator: Turn an annual salary into an hourly wage.
Hourly to Salary Calculator: Turn an hourly wage into annual, monthly and weekly pay.
Overtime Pay Calculator: Calculate time-and-a-half or double-time pay.
Pay Raise Calculator: See what a raise means per paycheck and per year.
Salary Calculator India (In-Hand): CTC to monthly take-home with EPF, gratuity and tax.
Central Government Salary Calculator (7th CPC): 7th CPC gross and net pay with DA, HRA, TA and NPS.

Personal Finance

Savings Goal Calculator: How long until you reach a savings target.
Emergency Fund Calculator: Set a 3–12 month emergency fund target.
Debt Payoff Calculator: Payoff time, interest and debt-free date.
Retirement Savings Calculator: Project your nest egg and monthly retirement income.

Tax & GST

Income Tax Calculator India: New vs old regime tax for FY 2024-25 to 2026-27.
UK Income Tax Calculator: Take-home pay after tax, NI, pension and student loan.
Australia Income Tax Calculator: Tax, Medicare levy, HELP and take-home pay.
GST Calculator: Add or remove GST, with CGST/SGST/IGST split.

Home & Real Estate

Mortgage Extra Payment Calculator: Interest and years saved by paying extra.
Rent vs Buy Calculator: Compare true costs of renting vs owning.
Rental Yield Calculator: Gross and net yield on a rental property.

Health & Wellness

TDEE Calculator: Maintenance calories and cut/bulk targets.
Macro Calculator: Calories into grams of protein, carbs and fat.
Water Intake Calculator: Daily water needs from weight and activity.
Sleep Calculator: Bedtimes and wake times by 90-minute cycles.
Pregnancy Due Date Calculator: Due date, weeks pregnant and trimester dates.
Protein Intake Calculator: Calculate grams of protein per day from body weight using an adult reference or your agreed g/kg target. Supports kg, lb and an optional equal meal split.
Ozempic Injection Reminder Planner: Plan calendar reminders for an existing once-weekly Ozempic injection prescription. Preview dates and download an ICS calendar without dose calculations.
Medication Reminder Planner: Build a printable daily reminder schedule from prescribed local times. Preview up to four times a day and export calendar events with requested alerts.

Auto & Travel

Fuel Cost Calculator: Trip fuel cost, total and per person.
Car Affordability Calculator: Turn a monthly budget into a car price.

Business & Freelancing

Freelance Rate Calculator: The minimum hourly rate you should charge.
Break-Even Calculator: Units and revenue needed to break even.

Everyday Tools

Online Notepad: Write, save, print and download plain-text notes.
RGB Color Codes: Mix RGB colors and convert between RGB, hex and HSL codes.
ASCII Table: Search and copy all 128 standard ASCII characters and codes.
HTML Editor: Edit HTML and see the result instantly in a sandboxed preview.
HTML Viewer: Paste HTML and safely view its rendered output online.
Word Counter: Count words, characters and paragraphs, with an estimated reading time.
Online Stopwatch: Measure elapsed time with start, pause, reset and lap recording.
Countdown Timer: Set an online timer with presets, pause, reset and an optional alarm.
Random Number Generator: Generate random integers in a range, with no-duplicate and sorting options.
PDF Text Cleaner: Remove unwanted line breaks from copied PDF text. Preserve paragraphs, optionally join split words, compare results and download TXT.
QR Code Generator: Generate free QR codes for links, PDF and image share URLs, text, Wi-Fi, contacts, email and SMS. Download PNG or SVG without an account.

Why use Mathmatives?

Understand the result. Calculators explain their methods and assumptions. Writing and developer tools include practical steps, examples and limits.

Nothing stands between you and the answer. Calculators run instantly in your browser, work on any phone, and your inputs never leave your device.

Built for real decisions. Every page adds the context the number needs: what counts as a good rental yield, why minimum payments barely move a credit card balance, and how accurate a due date estimate is.