Unit Converter Pro - Length, Weight, Currency

About

Unit Converter Pro is the fastest unit converter for Chrome. One popup, every category you actually need: length, weight, currency, temperature, area, volume, time, speed, plus engineering and cooking. A unit converter that opens in 200 ms and never asks to read your tabs. 🚀

🚀 WHY THIS UNIT CONVERTER IS DIFFERENT

Most unit converter extensions are bloated with ads, dead since 2019, or demand access to every site you visit just to convert units. Unit Converter Pro does the opposite: a privacy-first unit converter with zero host permissions, zero tracking, zero remote code, and a popup so fast it feels native. The built-in currency converter is the only thing that touches the network, and even that goes through a single endpoint that returns rates and nothing else.

Under the hood, this unit converter knows the math the other unit converter tools get wrong: temperature offsets (Celsius to Fahrenheit is not a ratio), gallons (US is 3.785 L, Imperial is 4.546 L), troy ounces vs avoirdupois ounces, nautical miles, light-years, parsecs. The unit math details that matter when the answer feeds a recipe, an invoice, or a flight plan.

⚡ EVERYTHING IN THE FREE UNIT CONVERTER PLAN

✓ Length converter (m, km, cm, mm, in, ft, yd, mi, nautical mile, light-year, parsec, AU)
✓ Weight converter (kg, g, mg, t, lb, oz, troy oz, stone, US ton, UK ton, grain, carat)
✓ Volume, area, time, and speed converters with every common unit covered
✓ Temperature converter with real Celsius, Fahrenheit, Kelvin, and Rankine math, not naive ratios
✓ Currency converter for the world's top 10 (USD, EUR, GBP, JPY, CNY, CAD, AUD, CHF, INR, BRL) with live exchange rates refreshed every 24 hours
✓ Live result as you type, no Convert button needed
✓ Swap From and To with a single click, copy result with one more
✓ Recent 5 conversions, 3 saved favorite unit pairs (km↔mi, kg↔lb, °C↔°F)
✓ 100 conversions per day, no signup, no email

🔓 WHAT PRO UNLOCKS

✦ Pro currency converter: 180+ currencies including BTC, ETH, gold (XAU), and silver (XAG)
✦ Live exchange rates refreshed on every conversion (Free uses a 24-hour cache)
✦ 30-day historical FX chart for every pair, so you can see whether to convert now or wait
✦ Engineering unit converter: pressure (Pa, bar, psi, atm, mmHg, torr), energy (J, kWh, BTU, cal), power (W, hp, BTU/h), force, electrical (V, A, Ω, F, H), magnetic, radiation
✦ Cooking unit converter with ingredient density: a cup of flour is not a cup of sugar by weight, and Pro knows the difference for 30+ common ingredients
✦ Unlimited saved favorites for the conversions you run every day
✦ History of the last 100 conversions, not just the last 5
✦ Unlimited daily conversions for engineers, traders, recipe writers, and designers who burn through hundreds

🎯 WHO USES THIS UNIT CONVERTER

Engineers checking that a 250 psi spec is really 17 bar. Traders running the currency converter to see whether the JPY rally is real. Recipe writers using the cooking unit converter to translate American cups to grams without guessing. Travelers comparing 80 km/h speed limits to mph. Tailors converting yards to centimeters. Fitness coaches turning 12 stones into kilograms for a client form. Anyone who has ever typed "180 lbs in kg" into Google and waited for the slow result page to load. This unit converter replaces all of that with a 200 ms popup.

🛠️ HOW THE UNIT CONVERTER WORKS

1️⃣ Pin the extension to your toolbar (one-time setup).
2️⃣ Click the icon. The unit converter popup opens instantly.
3️⃣ Pick a category, type your value, watch the result appear as you type.
4️⃣ Hit Copy or save the unit pair as a favorite if you use it often.
5️⃣ For the currency converter, the rate badge tells you live vs 24h-cached.

💡 REAL UNIT CONVERSION USE CASES

→ Convert that 12 fl oz recipe to milliliters before pouring
→ Use the currency converter to check whether $499 is more or less than €459 in your home currency right now
→ Convert a freight quote from kg to lb to compare carriers
→ Verify that 1 atm equals 14.7 psi for a pressure spec sheet
→ Pull up the 30-day USD/EUR chart before sending a wire transfer
→ Convert units of inches to centimeters for a tailor in seconds
→ Convert cups of flour to grams accurately, with the right density

🔒 PRIVACY YOU CAN VERIFY

This unit converter asks for one permission: storage, so your settings and favorites survive a browser restart. That is it. No host permissions, no content scripts, no access to the pages you visit. Every conversion runs locally inside the popup. The only network traffic the extension ever makes is a license check (a random device ID, no identity) and currency converter rate fetches (a single GET that returns rates and nothing else). No third-party analytics, no ad networks, no data brokers.

📊 PERFORMANCE & BENCHMARKS

Popup opens in under 200 ms on a typical laptop. Unit conversion math runs in microseconds. The whole bundle ships at roughly 90 KB gzipped, so Chrome stays light even with 30 tabs open. Currency converter rate fetches are cached so the popup stays snappy on slow networks.

🆚 WHY THIS UNIT CONVERTER OVER THE ALTERNATIVES

✓ Unlike Google's "180 lbs in kg" search, you do not need to open a new tab and wait for results
✓ Unlike most unit converter extensions, no host permissions, no tab access, no tracking, no ads
✓ Unlike calculator apps, every common unit is one click away with no menu diving
✓ Unlike standalone currency converter sites, the currency converter sits next to your length and weight tools
✓ Unlike command-line tools, no syntax to memorize, just type a number into the unit converter

🛡️ SECURITY

Manifest v3. Zero remote code. No external CDN dependencies. Every release is audited by an automated lint-remote-code check before submission. All unit converter logic ships inside the bundle. The codebase is small enough to audit in an afternoon, and we are happy to share details on request.

❓ FREQUENTLY ASKED QUESTIONS

Q: Does the unit converter work offline?
A: Yes. Every non-currency conversion works without any network. The currency converter uses cached rates when offline.

Q: How accurate is the currency converter?
A: Rates come from a major aggregator and are accurate to four decimals. Free uses a 24h-cached snapshot. Pro fetches live exchange rates on every conversion.

Q: Is my data sent anywhere?
A: Unit conversion math is 100 percent local. Currency converter requests send no identifying information beyond a random device ID for license validation.

Q: What is the difference between Monthly ($1.99) and Lifetime ($6.99) Pro?
A: Same Pro features, different commitment. Lifetime pays for itself in four months and never expires.

Q: Can I get a refund?
A: Within 30 days of purchase, yes. Email support and we will refund, no questions asked.

Q: Why a daily cap on Free?
A: To stop scripted abuse. The cap (100 conversions per day) is far higher than any human user reaches. If you hit it organically, Pro removes it instantly.

🚀 GET STARTED

Install the unit converter, pin it to your toolbar, and the next time you need to convert units, you are one click away. Length, weight, currency, temperature, time, area, speed, engineering, cooking: every unit converter you need in a single privacy-first popup. Try the unit converter free, upgrade only if you actually love it.