Calculators & Converters

Quick calculators for percentages, proportions, unit conversions, dates and business days. Each calculator explains its formula, shows intermediate steps where useful, and handles edge cases such as negative values or invalid dates. Instant results, keyboard-friendly, and no data sent anywhere.

Showing all 4 tools

Percentage Calculator Three percentage modes: X% of N, percentage change, and reverse percentage.

Rule of Three & Proportion Calculator Solve direct and inverse proportions with the classic rule of three.

Unit Converter Convert length, mass, temperature, area, volume, speed and data units instantly.

Date & Business Days Calculator Calculate date differences, add or subtract time, and count business days.

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