Clear calculators with real explanations
Essentia keeps a small set of practical calculators and pairs each one with worked examples, formulas, limits, and FAQs so you can learn as you calculate.
Essentia is an educational calculator site from PhaseOutLimit (POL). Each tool is paired with the formula, a worked example, known limits, and a short FAQ, so the page is usable as a lesson as well as a calculator.
Math runs in your browser. There is no account system, comments, or visitor upload store. Money, tax, and loan figures are teaching estimates. Confirm rates and contracts with a qualified professional and primary sources before you act.
Tools are available in English and Korean. About, privacy, contact, and guides stay in the header and footer on every page.
Math & quantities
Percentage Calculator Percent of a value, percent change, reverse percent, and “what percent is X of Y”. Probability Calculator Coin flips, dice odds, combinations, and simple conditional chance with the formula shown beside the answer. Unit Converter Length, mass, temperature, volume, and speed conversions with exact factors explained. Math & Scientific Calculator Arithmetic, powers, roots, and common scientific functions in the browser.
Everyday money math
VAT / Sales Tax Calculator Add or remove a tax rate from a net or gross amount. Rates vary by country and product. Tip & Bill Split Split a bill across people with an optional tip percentage. ROI Calculator Return on investment from cost and gain, shown as ratio and percent. Loan Amortization Monthly payment and interest share for a fixed-rate amortizing loan.
Time & patterns
Timezone Converter Compare a moment across IANA time zones using your browser clock APIs. Date Difference Days between dates, add or subtract days, and calendar helpers. Cron Expression Helper Explain a five-field cron string in plain language. Regex Tester Test a JavaScript-style pattern against sample text and see matches.