Free Online Calculators & Converters: Units, Dates, Percentages

Everyday Calculations Made Easy

Some calculations come up again and again — unit conversions, date math, percentages. Instead of searching for formulas, use these instant tools.

Unit Converter

The Unit Converter handles conversions across categories:

• Length — meters, feet, inches, km, miles
• Weight — kg, lbs, oz, grams
• Temperature — Celsius, Fahrenheit, Kelvin
• Volume — liters, gallons, cups, ml
• Area — sq meters, sq feet, acres, hectares
• Speed — km/h, mph, knots, m/s
• Data — bytes, KB, MB, GB, TB

Percentage Calculator

The Percentage Calculator solves three common questions:

What is X% of Y? — e.g., "What is 15% of 200?"

X is what % of Y? — e.g., "30 is what % of 150?"

% change from X to Y — e.g., "% change from 80 to 100?"

Date Difference Calculator

The Date Difference Calculator tells you exactly how much time is between two dates:

• Days, weeks, months, and years
• Business days (excluding weekends)
• Include or exclude the end date

Use cases: Calculate project durations, contract lengths, age differences.

Age Calculator

The Age Calculator computes your exact age:

• Years, months, and days
• Total days lived
• Next birthday countdown

Timezone Converter

The Timezone Converter helps with international scheduling:

• Convert between any two timezones
• See multiple timezones at a glance
• Account for daylight saving time

All Tools Are Instant

Every calculation happens in your browser — no network requests, no loading, no ads. Just fast, accurate results.