CalcoraBase
Calculators, Converters & Everyday Math
Clear, accurate tools for the math that turns up in everyday life — percentages and discounts, fractions, areas and volumes, averages, dates and unit conversions.
Every calculator shows how it got the answer: the formula, the steps and a worked example, so you can check the result and learn the method. Everything runs in your browser; nothing you type is sent anywhere.
Quick percentage: what is X% of Y?
Find the right tool
Math Calculators
Percentages, fractions, ratios, factors, powers and a scientific calculator.
Everyday Calculators
Shopping, school and daily-life math — discounts, tips, grades and more.
Money Math Calculators
Interest, loan payments, APR vs APY, savings goals and margins — exact arithmetic, no advice.
Geometry Calculators
Area, perimeter and volume of common shapes, with every formula shown.
Statistics & Probability Calculators
Averages, spread, probability and counting for any list of numbers.
Unit Converters
Two-way metric and imperial converters built on exact definitions.
Time & Date Tools
Date differences, ages, business days, time sums and timers.
Reference
Formula sheets, conversion tables and printable math charts.
Guides
Plain-English explanations of the methods behind the tools.
Popular calculators
- Percentage Increase CalculatorPercentage growth between two values, or a value increased by a given percent.
- Discount CalculatorSale price and savings after a percentage discount, including stacked discounts.
- Days Between DatesCount the days between two dates, optionally including the end date.
- Fraction CalculatorAdd, subtract, multiply, divide and simplify fractions and mixed numbers.
- Average CalculatorThe mean of any list of numbers, with the sum, count and median.
- Area CalculatorArea of rectangles, triangles, circles, trapezoids, sectors, polygons and more.
Quick conversions
- Centimeters to InchesConvert centimeters to inches with the formula and a quick table.
- Kilograms to PoundsConvert kilograms to pounds with the formula and a quick table.
- Degrees Celsius to Degrees FahrenheitConvert degrees Celsius to degrees Fahrenheit with the formula and a quick table.
- Feet to MetersConvert feet to meters with the formula and a quick table.
- Miles to KilometersConvert miles to kilometers with the formula and a quick table.
- Liters to US GallonsConvert liters to US gallons with the formula and a quick table.
- mph to km/hConvert miles per hour to kilometers per hour with the formula and a quick table.
- Hours to MinutesConvert hours to minutes with the formula and a quick table.
How CalcoraBase works
Accuracy first. Calculations avoid floating-point surprises — 0.1 + 0.2 gives 0.3, fractions are exact, and unit conversions use the official definitions (an inch is exactly 2.54 cm). Results are rounded only for display, and the calculators tell you when they have rounded.
Explained, not just answered. Each tool page includes the formula it uses, a worked example and notes on edge cases, such as what “percentage difference” means compared with “percentage change”, or whether a date count includes the end date.
Private by design. There are no accounts and no server-side calculations. The pages are static files; the math happens on your device. See the Privacy Policy for details.