Unit Converter Online — Free & Private
Convert length, weight, temperature and more between units. Free, private, and processed entirely in your browser — no upload, no account, no file ever leaves your device.
How to use Unit Converter
Convert length, weight, temperature and more between units. Everything runs in this tab — nothing is uploaded for the core job.
- Enter your content — Type or paste what you want to work with — Unit Converter runs immediately in your browser.
- Choose your options — Set any options Unit Converter offers.
- Get your result — Copy or download the result \u{2014} done entirely on your device, nothing uploaded.
Privacy proof for Unit Converter
This tool processes files in your browser. Open DevTools → Network while you run it: your document is not uploaded. After one online visit, many tools keep working with Airplane Mode on (libraries cached locally).
Popular tools
The highest-demand tools with full options — browse by category below for the rest.
Star any tool — it appears under Favorites on this device.
How this actually works
Each tool runs entirely with JavaScript already loaded in this page — PDF tools via pdf-lib and pdf.js, image tools via the browser's native Canvas API, and everything else with plain JavaScript. Your files or input are read into browser memory, processed, and handed back as a download or copyable result. This page itself is served by a small Laravel route; Laravel never sees your files either. The only backend in use is Supabase, and only for two optional things: signing in with a magic link, and — only if you're signed in — a log of which tool you ran and when. Honest limits worth knowing: Compress PDF flattens each page to a re-encoded image (great for scans, not ideal if you need selectable text after); HEIC conversion uses a small on-demand converter when the browser cannot decode HEIC natively (Safari often works without it); Fill PDF Form is best-effort for simple AcroForm fields, not a full Adobe Forms replacement; and Word/Excel/PowerPoint ⇄ PDF genuinely needs a server-side engine, so it isn't included — this build only ships tools that can honestly run client-side.
Questions people actually ask
Which unit categories are supported?
Length, weight/mass, and temperature — each with its own set of common units (metric and imperial mixed, so you can convert between systems, not just within one).
Does it update live as I type?
Yes — the converted value updates instantly as you type, with no separate "convert" step.
How is temperature converted?
Using the real conversion formulas (not a simple ratio) — Celsius, Fahrenheit, and Kelvin each have their own zero point, so the math genuinely differs from length or weight conversion.
How precise are the results?
Shown to a reasonable number of decimal places for everyday use — not intended for scientific-precision applications with exact tolerance requirements.
Can I convert between any two units in the same category?
Yes — pick any "from" and "to" unit within a category (e.g. miles to centimeters) and it converts directly, not just to/from a fixed base unit.
Can I swap the from/to units quickly?
Yes — a swap button flips the selected units and recalculates instantly.
Does this work offline?
Yes — all conversions are fixed mathematical formulas computed in your browser; no lookup service or internet connection is needed.
Is my input sent anywhere?
No — the conversion happens entirely in your browser as you type; nothing is transmitted.
Is this really free, and is there a file size limit?
Yes — no account, no paywall. Since processing happens in your browser's memory rather than uploading anywhere, the practical limit is your device's available RAM, not a server quota. Very large files (500+ pages) may run slower, especially for Compress and PDF→JPG.
Does anything about my file get sent anywhere?
No. Every tool runs with pdf-lib/pdf.js loaded in this page; your file is read into browser memory and never leaves it. The only network call this app makes for your account is Supabase auth — and that only stores which tool you ran and when, never file content.
Why isn't Word/Excel/PowerPoint → PDF included?
Converting Office formats accurately needs a real rendering engine (what Word or LibreOffice use internally) — no browser library does this reliably. Rather than ship a broken version, it's left out.
Does TechDriven Tools have OCR (text recognition)?
Yes — OCR PDF recognizes text in scanned or photographed pages using Tesseract.js, running entirely on your device, and gives you a searchable PDF or a plain text file. Nothing is uploaded for this either.
Can I use this without an internet connection?
Once the page and its libraries have loaded once, yes — the tools themselves need no network access. Signing in and viewing history do require a connection, since those talk to Supabase.
What happens to the "history" if I sign in?
Only a row per tool run — the tool's name and a timestamp. No filename, no file content, ever. You can see the full list any time via the History button.
Are the non-PDF utilities (password generator, JSON formatter, etc.) private too?
Yes — same rule as the PDF tools. Word Counter, Case Converter, Password Generator, UUID Generator, Base64, Hash Generator, JSON Formatter and JWT Decoder all run with plain JavaScript already loaded in this page; nothing you type or paste is sent anywhere.
Unit Converter, in depth
Convert length, weight, temperature, and more between units — instant, exact, no lookup table needed.
Features
Length
Meters, feet, inches, miles, kilometers, and more.
Weight
Kilograms, pounds, ounces, and more.
Temperature
Celsius, Fahrenheit, and Kelvin.
Live Conversion
Updates instantly as you type or change units.
Why use Unit Converter
- Convert a recipe or measurement between metric and imperial.
- Check a specification given in an unfamiliar unit system.
- Convert temperature readings between Celsius and Fahrenheit quickly.
- Verify a conversion without trusting a rounded mental estimate.
How it works
Each conversion uses a fixed, exact mathematical relationship between units — no lookup service or external rate feed involved, since physical unit conversions (unlike currency) don't change over time. Every calculation happens instantly using plain JavaScript math.
Does this work offline?
Yes — all conversions are fixed mathematical formulas computed in your browser; no internet connection or lookup service is needed once the page itself has loaded.
Why people search for Unit Converter
Convert length, weight, temperature and more between units. Bookmark /unit-converter if Unit Converter is part of your weekly workflow; the URL is stable and the tool stays free.
Unit Converter sits in our Converters group. The page is built so you can finish the job without creating an account, installing a desktop pack, or sending the payload to an unknown converter API.
Who Unit Converter is for
- A desktop suite is overkill for a one-page or one-photo job.
- You want a second opinion after another converter produced a weird output.
- You need a result now and do not want another account wall.
- The file or text is sensitive enough that uploading feels wrong.
Recommended workflow
Confirm from/to units → enter the value once → copy the result into the system of record.
- Open Unit Converter (also available from category hubs and ⌘K).
- Use the labeled fields or dropzone — options match what Unit Converter actually does.
- Run the tool and wait for local progress to finish.
- Download or copy the result, then verify on the device where you will share it.
Tips that improve results
- Change one setting at a time when you are comparing quality or layout.
- Keep the original until stakeholders accept the download.
- Rename the output with date + purpose before you attach it to email.
- On phones, plug in power for large PDFs, videos, or spreadsheets.
- Prefer UTF-8 text for developer converters; weird encodings cause most “broken” results.
- Start with a non-sensitive sample so you learn the options before the real file.
Common mistakes with Unit Converter
- Expecting Unit Converter to replace a full desktop suite for every edge-case format.
- Skipping a sample check and discovering a bad export after the original was deleted.
- Chaining many lossy image/PDF steps when one careful pass would have been enough.
- Using a public computer without clearing downloads afterward.
Privacy model
Processing for Unit Converter is designed to stay in the browser. Laravel serves the page; it does not receive your file bytes for conversion. Optional Supabase auth only stores which tool you ran and when — never filenames or contents.
Related tools
- Temperature Converter
- Timezone Converter
- Number Base Converter
- Roman Numeral Converter
- Number to Words Converter
- Date Difference Calculator
FAQ — Unit Converter
Is Unit Converter free to use?
Yes. Unit Converter on TechDriven Tools is free — no account, no watermark, and no paywall for the core workflow.
Does Unit Converter upload my file or text?
No for processing. Unit Converter runs in your browser tab. Optional sign-in never stores file contents — only tool names and timestamps if you enable history.
When should I use Unit Converter?
Use Unit Converter for Converters jobs where privacy and speed matter: quick one-offs, sensitive inputs, or checking another app’s result without another upload site.
Will Unit Converter work on my phone?
Yes in a modern mobile browser. Large inputs can take longer because your device does the work locally.
What are the limits of Unit Converter?
There is no server quota from us. Limits are your device memory, battery, and formats the browser can decode. Unit Converter will not pretend to support server-only Office or cloud-AI pipelines.
How is Unit Converter different from upload-based sites?
Upload converters send your content to someone else’s server. Unit Converter keeps the transform on-device whenever the format allows, which is the safer default for confidential documents, photos, tokens, and configs.
Bottom line
If you need Unit Converter done quickly and privately, start at /unit-converter, run it once on a sample, then process the real input. That is how TechDriven Tools stays competitive: honest capabilities, labeled UI, and content that matches what the tool actually ships.
From our blog: How to Convert Units of Measurement Online