18 free tools
Math calculators and converters
Everyday math is where small mistakes cost the most: a percentage flipped the wrong way, a grade average that forgets credit weights, a recipe scaled by eye. These calculators handle percentages and percent change, averages, median, standard deviation, GPA and grade targets, speed and distance, Roman numerals, and unit and temperature conversions.
All math tools
Average Calculator
Average calculator that finds the mean of any list of numbers, plus the median, sum, count, and range. Paste numbers separated by commas or lines.
Coin Flip
Flip a coin online for a fair heads or tails. Flip once or up to 100,000 times and track the running tally and percentages. Free, instant, no ads.
Data Storage Converter
Data storage converter for bytes, KB, MB, GB, TB, bits, and binary GiB/TiB. See why a 1 TB drive shows 931 GB, and convert every unit at once.
Dice Roller
Dice roller with D&D notation: type 2d6+3 or 4d6kh3, roll with advantage, see every die and the last 20 rolls. Fair crypto-grade randomness.
GPA Calculator
GPA calculator for college and high school: enter letter grades and credits to get unweighted and weighted GPA, with honors and AP/IB boosts.
Grade Calculator
Grade calculator: enter scores and weights to get your weighted class grade and letter grade, then see exactly what you need on the final.
Median Calculator
Median calculator that finds the middle value of any list, with mean, mode, range, and quartiles, plus the step-by-step sorted work shown.
Percentage Calculator
Percentage calculator for the 3 common questions: X% of Y, X is what percent of Y, and percent change. Plus percent increase and decrease.
Random Name Picker
Random name picker: paste a list and draw one or several winners at once. Fair cryptographic randomness, no repeats, and optional winner removal.
Random Number Generator
Random number generator for any range: pick 1 to 1,000 numbers with or without repeats, sorted or not. Unbiased, cryptographically secure, instant.
Random Team Generator
Random team generator: paste names and split them into any number of teams or groups of a set size. Balanced sizes, optional captains, one-click copy.
Recipe Scaler
Recipe scaler that resizes ingredient lists by servings. Paste a recipe, handles fractions like 1 1/2 and ½, and returns kitchen-friendly measurements.
Roman Numeral Converter
Roman numeral converter that works both ways: turn numbers 1 to 3,999 into Roman numerals or decode numerals, with a step-by-step breakdown.
Speed Distance Time Calculator
Speed distance time calculator: solve for speed, distance, or time in miles or km. Get mph, km/h, and pace per mile or km in one click.
Standard Deviation Calculator
Standard deviation calculator: paste numbers, get sample and population SD, variance, mean, sum, min, and max instantly. Free, no sign-up.
Temperature Converter
Temperature converter for Fahrenheit, Celsius, and Kelvin. Enter one value, see all three at once, with exact formulas and absolute-zero checks.
Unit Converter
Unit converter for length, weight, and US volume: inches to cm, lb to kg, cups to mL, gallons to liters. Exact factors, instant results.
Wheel Spinner
Spin the wheel to pick a random name, choice or winner. Edit entries, remove winners after each spin and share your wheel by link. Fair crypto randomness.
About these tools
Each tool shows the formula behind the answer, so you can check the work or copy the method into a spreadsheet. A 20% rise followed by a 20% drop leaves you 4% below where you started, not back at zero. A 3.0 GPA from 15 credits needs far more A's to move than a 3.0 from 60 credits hints at. Seeing the math makes those traps obvious.
Random tools like the number generator, dice roller, coin flip, and name picker use your browser's cryptographically secure generator, so results are fair enough for giveaways and classroom picks. Everything runs on your device and nothing you type is uploaded.