Math & Numbers
Calculate the percentage increase between an original value and a new value
percentage-increase-calculatorMath & Numbers
Run simple linear regression on paired numeric data and inspect slope, intercept, correlation, and predictions
regression-calculatorMath & Numbers
Calculate the perimeter of various geometric shapes
perimeter-calculatorMath & Numbers
Calculate percentages, percentage changes, and percentage relationships between numbers
percentage-calculatorDate & Time
Generate recurring dates based on a pattern
recurring-event-generatorMath & Numbers
Perform arithmetic operations on fractions
rational-calculatorFinance
Calculate if refinancing your loan will save you money
refinance-calculatorFinance
Compare renting versus buying a home to make informed housing decisions
rent-vs-buyMath & Numbers
Convert US liquid pints to liters with configurable decimal precision
pint-to-literMath & Numbers
Convert US liquid quarts to liters with configurable decimal precision
quart-to-literMath & Numbers
Smallest primitive root mod n with certificate g^(φ/q) ≠ 1, root count φ(φ(n)), up to 50 listed roots, and candidate verification. n ≤ 10¹².
primitive-root-finderMath & Numbers
Exact π(n) via a single-pass Sieve of Eratosthenes (n ≤ 10⁷) with n/ln n comparison, density, average gap, and the largest prime ≤ n.
prime-counting-function