Arithmetic Calculator
Powerful calculator with basic, advanced, and scientific modes.
Use Tool →Math
Quick math calculators for everyday calculations. Find percentages, calculate ratios, and solve common math problems instantly. All calculations happen in your browser with no data sent to any server.
These calculators serve students tracking grades and computing GPA, shoppers figuring out discounts and splitting tips, and professionals converting between measurement units for length, weight, temperature, and volume. The unit converter covers SI units (International System of Units, established by the General Conference on Weights and Measures) as well as US customary and imperial measurements used in everyday life.
All calculations use IEEE 754 double-precision floating-point arithmetic as implemented by JavaScript engines, providing up to 15–17 significant decimal digits of precision. The percentage calculator handles all common operations: finding X% of Y, determining what percentage X is of Y, and computing percentage change between two values. Results are displayed with appropriate precision, and the tip calculator rounds to the nearest cent for practical use.
Percentage Calculator
Calculate percentages, percentage change, and more.
Use Tool →Grade Calculator
Calculate grades, weighted averages, final exam scores, and grade curves instantly.
Use Tool →GPA Calculator
Calculate your GPA from course grades and credits.
Use Tool →Unit Converter
Convert length, weight, temperature, area, and speed units.
Use Tool →Tip Calculator
Calculate tips by percentage, split bills for groups up to 100, and see per-person totals.
Use Tool →Coin Flip
Flip a virtual coin with 3D animation, cryptographic randomness, multi-coin mode, and session statistics.
Use Tool →Unit Circle Reference
Interactive unit circle with all 16 special angles, exact trigonometric values, and reference triangles.
Use Tool →Frequently Asked Questions
How do I calculate a percentage of a number?
To find X% of a number, multiply the number by X and divide by 100. For example, 15% of 200 is 200 × 15 ÷ 100 = 30. Our percentage calculator handles all common percentage operations: finding a percentage, calculating what percentage one number is of another, and finding percentage increase or decrease.
What is a GPA and how is it calculated?
GPA (Grade Point Average) is a standardized measure of academic performance used primarily in the United States. It is calculated by assigning point values to letter grades (typically A=4.0, B=3.0, C=2.0, D=1.0, F=0.0), multiplying each by the course credit hours, and dividing the total points by total credit hours.
How do I calculate a tip?
Multiply the bill amount by the tip percentage divided by 100. For example, a 20% tip on a $50 bill is $50 × 0.20 = $10. Our tip calculator also splits the total evenly among multiple people and shows the per-person amount including tip.
How does the unit converter work?
Our unit converter covers length, weight, temperature, volume, area, speed, and data storage units. All conversions use exact ratios defined by the International System of Units (SI), established by the General Conference on Weights and Measures (CGPM). For example, 1 inch is defined as exactly 25.4 millimeters (standardized internationally since 1959). Temperature conversions use the exact formulas: °F = °C × 9/5 + 32 and K = °C + 273.15. Results are calculated instantly in your browser with no rounding errors in the conversion factors themselves.
How is a weighted grade average calculated?
Each assignment or exam is multiplied by its weight (the percentage it contributes to the final grade), then the products are summed and divided by the total weight. For example, if homework worth 30% of the grade scores 90 and an exam worth 70% scores 80, the weighted average is (90 × 0.30 + 80 × 0.70) = 27 + 56 = 83. This method ensures that higher-weight components have proportionally more influence on the final grade. Our grade calculator handles any number of categories with custom weights.