A little help with the numbers

Everyday questions.
Simple answers.

Calculate, convert, and get on with your day. A thoughtful collection of handy tools, all in one quiet corner of the web.

69 useful toolsFree to useLocal calculations

A LITTLE PERSPECTIVE1 mile↓ A change of units1.609344 kmSame distance. A different way to see it.

What would you like to work out?

69 tools ready to help

Compound interest projection

Model monthly compounding and regular end-of-month deposits.

Energy, pressure and power converter

Convert compatible units using explicit physical definitions.

Resting metabolic rate estimator

Estimate adult resting energy expenditure with Mifflin–St Jeor.

Macronutrient allocation calculator

Turn your chosen calorie and percentage allocation into grams.

CSV to JSON converter

Parse quoted CSV into JSON objects without uploading the data.

Markdown to HTML converter

Create and preview a safe, documented Markdown subset.

Regular expression tester

Inspect JavaScript regex matches in a time-limited worker.

JSON workspace

Format, validate, compare and transform JSON with bounded tree and graph views.

Tiny language playground

Explore variables and arithmetic in a small local interpreter.

HTML and static Pug workspace

Format, minify or structurally check HTML, inspect an inert preview and convert a static Pug subset.

Structured data workspace

Convert and inspect JSON, XML, YAML, TOML, CSV, TSV and JSON strings with explicit mappings.

CSS and JavaScript formatter

Beautify or minify source text without executing it.

Text escaping and encoding

Encode Base64 and URLs or escape documented markup, string-literal, CSV and SQL dialects.

UUID and ULID batch generator

Generate UUID v4, UUID v7 or ULID identifiers in bounded batches.

Cron builder and explainer

Build or inspect five-field cron expressions with UTC examples.

Integer and bitwise expressions

Evaluate bounded signed 64-bit integer expressions without eval.

Scientific calculator

From everyday arithmetic to powers, roots and trigonometry.

Percentage calculator

Find a percentage of any number in one simple step.

Discount calculator

See the price after a percentage discount.

Length converter

Meters, miles, feet and all the distances between.

Mass converter

Convert grams, kilograms, pounds and ounces.

Area converter

Square units, acres and hectares, made simple.

Volume converter

Liters, milliliters and US liquid measures.

Temperature converter

Switch between Celsius, Fahrenheit and Kelvin.

Speed converter

Meters per second, kilometers per hour, mph and knots.

Time converter

Milliseconds to weeks, without the mental math.

Data-size converter

Know the difference between MB, MiB, bits and bytes.

Number-base converter

Exact integer conversion from binary to base 36.

Kilograms to Grams (kg to g) Converter

Convert kilograms to grams with a fixed kg-to-g calculator, a worked example and guidance on decimal weights.

Grams to Kilograms (g to kg) Converter

Convert grams to kilograms, including quantities below one kilogram, using the exact 1000-gram relationship.

Kilograms to Pounds (kg to lb) Converter

Convert kilograms to avoirdupois pounds using the international pound definition, with a clear kg-to-lb example.

Pounds to Kilograms (lb to kg) Converter

Convert decimal pounds to kilograms with the exact international pound factor and tips for pounds-and-ounces inputs.

Centimeters to Inches (cm to in) Converter

Convert centimeters to decimal inches using 2.54 cm per inch, with examples for measurements and dimensions.

Inches to Centimeters (in to cm) Converter

Convert inches to centimeters, including decimal-inch measurements, with an exact inch-to-centimeter formula.

Meters to Feet (m to ft) Converter

Convert meters to international feet with a worked example and an explanation of decimal feet versus feet and inches.

Feet to Meters (ft to m) Converter

Convert international feet to meters and learn how to enter mixed feet-and-inches measurements correctly.

Kilometers to Miles (km to mi) Converter

Convert kilometers to statute miles using the exact international mile definition, with a 5 km worked example.

Miles to Kilometers (mi to km) Converter

Convert statute miles to kilometers with an exact miles-to-km factor and an example for road distances.

Celsius to Fahrenheit (°C to °F) Converter

Convert Celsius temperatures to Fahrenheit with the 9/5 scale factor, 32-degree offset and practical examples.

Fahrenheit to Celsius (°F to °C) Converter

Convert Fahrenheit readings to Celsius by removing the 32-degree offset, then applying the 5/9 scale factor.

Liters to Milliliters (L to mL) Converter

Convert liters to milliliters with the exact metric relationship and examples for bottle and container capacities.

Milliliters to Liters (mL to L) Converter

Convert milliliters to liters and express small liquid volumes as decimal liters, with a 750 mL example.

Kilometers per Hour to Miles per Hour (km/h to mph)

Convert speed from kilometers per hour to miles per hour, with a 100 km/h example and an exact distance factor.

Miles per Hour to Kilometers per Hour (mph to km/h)

Convert miles per hour to kilometers per hour using the exact international mile factor, with a 60 mph example.

Hours to Minutes (h to min) Converter

Convert decimal hours to minutes, with examples explaining why 1.5 hours means 90 minutes rather than 150.

Minutes to Hours (min to h) Converter

Convert minutes to decimal hours with a clear formula and guidance for interpreting the fractional-hour result.

Made for the everyday

Clear inputs, useful examples, and formulas you can understand.

How processing works

Calculations run locally in your browser. Hosting and enabled third-party services involve data processing; see our Privacy Policy.

A little precision goes a long way

Decimal results use floating-point arithmetic; base conversions use exact 64-bit integers.

Password and authentication guides

Learn before using the separate sensitive workspace. Launch is currently gated pending verified isolation.

Choosing a random password

A random password is useful when a password manager can store it for you. Length, uniqueness and the way it is generated matter more than a visual strength meter.

Understanding EFF-style passphrases

A passphrase combines independently selected random words. It is not a quotation, a sentence you invent, or a list of your favorite things.

Digests, HMAC and bcrypt explained

These operations solve different problems. A digest is unkeyed, HMAC uses a secret key to authenticate a message, and bcrypt is a salted password-hashing function. None is encryption.

Focused developer tasks

Open one task with its own instructions, example and limits, or use the combined workspaces for more operations. These focused pages are currently in English.

JSON formatter

Pretty-print strict JSON with 2, 3 or 4 spaces, retaining array order and checking duplicate keys and integer precision.

JSON validator

Check strict JSON syntax with line and column diagnostics, duplicate-key detection and unsafe-integer checks. No schema validation.

JSON minifier

Remove unnecessary JSON layout whitespace after strict syntax, duplicate-key and numeric-precision checks. Preserve strings and array order.

JSON value comparison

Compare two strict JSON documents by decoded values. Report added, removed and changed values using JSON Pointer paths; array order matters.

JSON document to JSON string

Wrap a strict JSON document in one quoted JSON string, escaping its quotes and backslashes without executing code.

JSON string to JSON document

Unwrap one quoted JSON string containing a complete JSON document, validate the inner JSON and format its decoded value.

JSON to YAML converter

Convert supported JSON values to YAML with explicit type checks. Review quoted strings, normalized formatting and comments limitations.

YAML to JSON converter

Convert a supported YAML document to JSON. Reject duplicate keys, aliases, custom tags and values that cannot be represented safely.

XML to ordered JSON tree

Parse bounded XML 1.0 into an explicit ordered JSON node tree, retaining attributes and mixed text. No external entities or schema fetching.

JSON records to CSV converter

Convert a nonempty JSON array of flat records to CSV. Preserve string cells or explicitly stringify safe numbers and booleans with type loss.

CSV to TSV converter

Convert comma-separated tables to tab-separated text, preserving string cells, header order and quoted delimiters without type guessing.

XML parser and serializer

Check and reserialize XML 1.0 with an ordered node mapping. Preserve mixed-content whitespace without adding speculative indentation.

YAML syntax checker

Check the supported YAML syntax and value subset, rejecting duplicate keys, aliases and custom tags. No application schema validation.

Inert HTML layout preview

Inspect a restricted HTML layout in an empty sandbox. Remove active content and resource references from the preview; original source stays unchanged.

HTML structural checker

Check explicit HTML tag nesting, attribute quotes and duplicate attributes within a bounded subset. This is not full HTML5 conformance validation.

Static Pug to HTML converter

Convert a limited markup-only Pug/JADE subset to HTML without executing templates. Literal tags, indentation, text and quoted attributes only.

HTML text escaper

Encode HTML-sensitive characters as entities for an explicit text transformation. This does not sanitize a whole document or validate URLs.

SQL standard string literal escaper

Wrap text as one SQL standard single-quoted string literal by doubling apostrophes. Use parameterized queries for database input.

Dates, data and practical generators

Focused tools with explicit rules, worked examples and limits. These pages are currently in English.

Everyday questions.Simple answers.