Haru ToolsLess figuring out.
More getting on with it.
Calculate a discount, count your words, or make sense of dates. Simple tools for the little things that come up every day.
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8 tools, ready when you are
Percentage Calculator
Find a percentage of a number or measure the percentage change between two values.
Everyday mathDiscount Calculator
Calculate the amount saved and the price after a percentage discount.
ShoppingDate Difference Calculator
Count signed calendar days between dates or add and subtract a number of days.
Dates & timeAge Calculator
Calculate elapsed calendar years, months, and days from a birth date to a reference date.
Dates & timeCharacter and Word Counter
Count visible characters, characters without whitespace, word groups, lines, and UTF-8 bytes.
WritingUnit Price Calculator
Compare package prices on a common weight or volume basis.
ShoppingSquare Metres to Pyeong Converter
Convert area between square metres (m²) and Korean pyeong.
Everyday mathExact Bill Splitter
Divide an integer total fairly while keeping every smallest currency unit accounted for.
Everyday mathNo matching tools. Try another word or choose All tools.
Made for the everyday
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Every tool includes its formula, examples, and limits.
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Explore guidesPercentage vs Percentage Points: Choose the Right Comparison
Understand the baseline behind a percentage, compare rates correctly, and avoid adding stacked discounts.
How to Count Days Between Dates Without an Off-by-One Error
Choose elapsed or inclusive counting, understand calendar-day offsets, and keep dates separate from timestamps.
Characters, Words, and Bytes: Why Text Counts Disagree
Learn what grapheme clusters, whitespace-separated word groups, line counts, and UTF-8 bytes actually measure.
How to Compare Unit Prices When Package Sizes Differ
Normalize grams, kilograms, millilitres, and litres to compare equivalent quantities and spot misleading package comparisons.