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Business Calculators 8 tools Profit margin, markup, break-even, and cash runway calculators that help you make fast, accurate business decisions. Developer Tools 10 tools JSON formatting, validation, minification, and conversion tools that run entirely in your browser — your code never leaves your machine. Home & Construction Estimators 5 tools Paint, flooring, tile, concrete, and gravel estimators with metric and imperial units, waste allowances, and package counts. Time & Date Tools 4 tools Date differences, business days, time-zone conversions, and meeting-overlap planning with correct daylight-saving handling. Image Tools 3 tools Resize, compress, and convert JPG, PNG, and WebP images privately — processing happens locally, and your files are never uploaded.
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View all tools → Business Profit Margin Calculator Calculate profit margin percentage, gross profit, and markup from revenue and cost, with rounding you control. Business Markup Calculator Calculate markup percentage, markup amount, and the selling price you need from any cost figure, with a margin cross-check. Business Gross Profit Calculator Calculate gross profit and gross margin from revenue and cost of goods sold, with a target-revenue mode. Business Discount Calculator Calculate the final price after any percentage discount, the exact amount saved, and the discount between two prices. Business Break-Even Calculator Find how many units you must sell — and at what revenue — to cover your fixed costs, from price and variable cost. Business Cash Runway Calculator Estimate how many months your business can operate before running out of cash, from balance, expenses, and income. Business Billable Hourly Rate Calculator Set a freelancer or agency hourly rate that covers your target income, overhead, taxes, and unpaid time. Business Payment-Processing Fee Calculator See exactly what a payment processor takes from a transaction: percentage fee, fixed fee, and what you actually receive. Developer JSON Formatter & Validator Format and validate JSON with readable indentation, precise error messages, and byte-size stats — fully local. Developer JSON Minifier Compress JSON to its smallest valid form — strip all whitespace, count the bytes saved, and copy or download. Developer CSV to JSON Converter Convert CSV files and pasted tables into JSON objects with automatic delimiter detection and header mapping. Developer JSON to CSV Converter Convert a JSON array of objects into RFC 4180 CSV with correct quoting, column union, and copy or download. Developer Base64 Encoder & Decoder Encode text or files to Base64 and decode back, with UTF-8 handling, validation, and size stats — fully local. Developer AI Token Counter Estimate tokens and API cost for any prompt across GPT-4o, Claude Sonnet 4, and other models — fully local. Developer Regex Tester Test regular expressions live against your own text with match highlighting, capture groups, and flags — fully local. Developer Text Diff Checker Compare two blocks of text line by line with added, removed, and unchanged highlighting plus change statistics — fully local. Developer Unix Timestamp Converter Convert between Unix seconds, Unix milliseconds, ISO 8601, and human-readable local time — live, fully local. Developer UUID Generator Generate RFC 4122 version-4 UUIDs from cryptographically secure randomness — one at a time or in bulk, fully local. Home Paint Calculator Estimate how many gallons or liters of paint you need for a room, from wall measurements, openings, and coats. Home Flooring Calculator Estimate the flooring boxes you need for a room: area from length and width, waste allowance, pack count, and cost. Home Tile Calculator Estimate the tiles and boxes you need for a floor or wall, with waste, grout, tile size, and total cost. Home Concrete Calculator Estimate concrete volume in cubic yards or meters and the number of bags needed for a slab, footing, or pad, with cost. Home Gravel Calculator Estimate gravel volume in cubic yards or meters, weight in tons, and cost for a driveway, path, or base layer. Time Date Difference Calculator Calculate the exact number of days, weeks, months, and years between two dates — with a single trusted method. Time Business Days Calculator Count business days between dates or add business days to a date — weekends and your own holidays excluded. Time Time Zone Converter Convert any date and time between IANA time zones with correct daylight-saving handling and explicit offsets. Time Meeting Overlap Planner Find the time windows when teams in different time zones can meet, using their local work hours and DST-aware math. Image Image Resizer Resize JPG, PNG, WebP, and GIF images to any maximum dimension, preserving aspect ratio — on your device. Image Image Compressor Compress JPG and WebP images with a quality slider, live size savings and dimensions, processed fully on your device. Image JPG, PNG & WebP Converter Convert images between JPG, PNG, and WebP with a quality control — locally, with live size and dimension stats.
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Every calculator, converter, and image tool executes in your browser. Your numbers, pasted text, and image files are never sent to a server, logged, or stored — the only things kept locally are preferences like your theme.
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Answers you can verify
Every tool shows its formula, its assumptions, a worked example, and its limitations. If you spot an error, the correction link on every page goes straight to a human review queue. See our methodology.