✦ Ready to convert? Use the tool below — or read the guide first ↓

Unit Converter Studio

How to Use

Pick a category from the left panel, type any value in the FROM field, choose your units — the result updates instantly as you type. Hit ⇅ Swap to reverse the conversion.

🔒 100% Private

CrunchyUnits runs entirely in your browser. No values, no queries, no data is ever sent to any server. Close the tab — history is gone by design. Zero tracking.

📖 Glossary

SI = Système International. Base unit = the reference unit for a category (e.g., metre for length). Factor = how many base units one unit equals. Temperature uses formulas, not factors.

⚡ Unit Facts

One light-year = ~9.461 × 10¹⁵ metres. A horsepower was defined by James Watt as the power of one horse lifting 550 lbs one foot per second. 1 byte = 8 bits, always.

💡 Pro Tips

Use Tab to jump between inputs and unit selectors. Enable scientific notation for very large or very small values. The All Conversions panel shows every unit at once.

📦 17 Categories

Length · Mass · Volume · Area · Temperature · Time · Speed · Energy · Power · Pressure · Digital Storage · Data Transfer · Frequency · Angle · Force · Torque · Fuel Economy

⭐ Favorites

Click any result row in the All Conversions table to instantly set it as your TO unit. Your last-used category and units are remembered automatically for your next visit.

Who Uses CrunchyUnits?

CrunchyUnits is the free unit converter of choice for anyone who needs fast, accurate conversions without installing software or sharing data with a server:

🔬 Scientists & Researchers 👷 Engineers & Technicians 🍳 Cooks & Bakers 🏫 Students & Teachers ✈️ Travellers & Expats 💻 Developers & IT Pros 🏗️ Architects & Builders 🏥 Medical & Health Professionals

🔒 Why a Client-Side Unit Converter?

🕵️ Zero Data Exposure

Server-based converters log your queries — every value you enter is a request to their infrastructure. CrunchyUnits converts entirely in JavaScript in your browser. No request is ever made. Nothing is logged.

⚡ Instantaneous Results

No network latency. No API call. Results update as you type — every keystroke triggers a local calculation. Even on a slow connection or completely offline, conversions are instant.

🌐 Works Offline

Once the page loads, CrunchyUnits works without any internet connection. Convert units on a plane, in a lab with no Wi-Fi, or anywhere your browser can run. Your workflow is never dependent on connectivity.

📦 300+ Units, 17 Categories

From ångströms to parsecs, from bits to petabytes, from Rankine to Delisle — CrunchyUnits covers every unit category you're likely to need, all loaded instantly without any additional server requests.

💸 Always Free

No subscriptions, no API keys, no rate limits. CrunchyUnits is permanently free for personal use, supported only by non-intrusive display advertising. Every unit, every category, forever.

🔓 Pure JavaScript

Built on zero third-party libraries for the conversion engine — just pure JavaScript and verified unit factors. No external dependencies, no CDN calls for the math. Every formula is auditable right in the source.

💡 Tips for Getting the Most Out of CrunchyUnits

Use the All Conversions panel for quick scanning — when you enter a value, the grid at the bottom of the converter shows every available unit in that category simultaneously. Click any row to instantly set it as your target unit.

Enable Scientific Notation for extreme values — converting nanometres to light-years or bits to petabytes produces numbers with many zeros. Enable the Scientific Notation option in the sidebar to display results in standard scientific form.

Use Tab to navigate the converter without a mouse — press Tab to cycle through the value input, FROM unit selector, Swap button, and TO unit selector. Efficient for rapid consecutive conversions.

Adjust Decimal Places for your use case — the default is 4 decimal places. For engineering work, set it to 8 or Full Precision. For casual use, 2 is usually sufficient. The option is in the sidebar under Options.

Hit ⇅ Swap to reverse any conversion instantly — if you just converted km to miles and now need miles to km, click Swap. The values and units flip and the result recalculates immediately.

Your last-used category and units are remembered — CrunchyUnits saves your most recent category and unit selections in your browser. When you return, you pick up right where you left off — no re-selecting needed.

❓ Frequently Asked Questions

Is CrunchyUnits really free? ▶

Yes — completely free with no premium tier, no usage limits, and no sign-up required. CrunchyUnits is supported by non-intrusive display advertising.

Are my conversion values sent to a server? ▶

Never. All conversions are calculated locally using JavaScript running in your browser. No value you enter is ever transmitted to any server. Close the tab and your history is gone instantly.

How many units and categories are supported? ▶

CrunchyUnits supports 300+ units across 17 categories: Length, Mass, Volume, Area, Temperature, Time, Speed, Energy, Power, Pressure, Digital Storage, Data Transfer, Frequency, Angle, Force, Torque, and Fuel Economy.

How accurate are the conversion factors? ▶

Conversion factors are sourced from the NIST (National Institute of Standards and Technology) and the SI Brochure where applicable. Temperature conversions use exact formulas. For critical engineering, scientific, or medical applications, always verify results against an authoritative reference.

Can I use CrunchyUnits offline? ▶

Yes. Once the page has fully loaded, all 17 categories and 300+ units work without an internet connection. Only the visitor counter and ad units require connectivity. Great for field work, travel, or restricted networks.

How does temperature conversion work? ▶

Temperature uses offset formulas rather than simple multiplication factors, because temperature scales have different zero points. CrunchyUnits handles Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Réaumur, and Rømer using their exact conversion formulas.

What is the All Conversions panel? ▶

When you enter a value, the All Conversions grid shows the result in every unit in the current category simultaneously. This is useful when you need to scan multiple units at once — for example, seeing a length in inches, feet, centimetres, and metres all at the same time.

Does CrunchyUnits remember my preferences? ▶

Yes. Your last-used category and unit selections are saved in your browser's localStorage and restored on your next visit. Your display options (decimal places, scientific notation, thousands separator) are also remembered.

What browsers are supported? ▶

CrunchyUnits works on any modern browser: Chrome 100+, Firefox 100+, Safari 15+, Edge 100+, and Brave. Internet Explorer is not supported.

Will you add more unit categories? ▶

Yes — new categories are planned. If you need a specific unit or category not currently available, use the Contact Us link in the footer to send a request. Commonly requested categories are prioritised.

⚖️ CrunchyUnits vs. Other Unit Converters

Feature	CrunchyUnits	Typical Online Converters
Values Sent to Server?	✔ Never — 100% local	✘ Every query is a server request
Works Offline?	✔ Yes, once page is loaded	✘ Requires active internet
Instant Results (no latency)?	✔ Updates as you type	✘ Waits for network round-trip
Account Required?	✔ Never	✘ Sometimes required
Ad-Free Option?	✔ Non-intrusive ads only	✘ Often heavy ad loads
All Conversions at Once?	✔ Full grid, every unit	✘ Usually one pair at a time
Scientific Notation Support?	✔ Built-in toggle	✘ Rarely available
Conversion History?	✔ Local session history	✘ Usually none

⚠ Features of other tools vary. Note that for server-based converters, every value you enter is transmitted to their infrastructure — a consideration if you are converting sensitive measurements.

Why CrunchyUnits Stands Out as a Private Unit Converter

CrunchyUnits is a fully client-side unit converter with 300+ units across 17 categories. No values are ever transmitted to a server, no queries are logged, and no account is required. Results update instantly as you type, with full conversion tables, scientific notation, and conversion history — all running locally in your browser.

Other Popular Unit Converter Tools

Here are some well-known alternatives for unit conversion. These tools send your queries to their servers — useful for more specialized conversions, but worth knowing when privacy matters.

UnitConverters.net ConvertUnits.com RapidTables Wolfram Alpha Metric Conversions ConvertLive

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