Any unit. Any value. One clean swap.
Length, weight, area, volume, temperature, speed, time — plus thirteen industry categories. The answer appears as you type, and none of it leaves your phone.
Try it now
Tap a result to copyEveryday units, free, no account.
Eight categories cover most of what people actually convert — including the Chinese units other converters forget: 市尺, 斤, 亩. Tap one to load it into the converter above.
Built like a tool, not a feed.
No banners, no interstitials, no prompt to rate the app mid-calculation. The number you typed stays the biggest thing on the screen, and every unit in the category updates with it.
The professional pack, unlocked once.
Engineering, baking, marine, textile, jewellery, print and energy — the units that usually live in a spreadsheet. Buy it once, restore it on every device you own.
Your numbers never leave the phone.
UnitSwap has no server to send anything to. That is the whole architecture.
Read the privacy policy- No account Nothing to sign in to, nothing to remember. Open the app and convert.
- No network Every conversion runs on the device. It works on a plane, in a basement, on a site with no signal.
- No analytics There is nothing to collect and nothing to sell, so the free units stay free without tracking you.
Before you install.
The short answers, in the order people usually ask them.
Is UnitSwap free?
Yes. Length, weight, area, volume, temperature, time, speed and amount-in-Chinese characters are free, with no ads and no account. The professional pack is a single $6 purchase that you can skip entirely — the free app never nags you to buy it.
Does it need an internet connection?
No. The app does not request network access at all. Everything is calculated from a unit table stored in the app, so results are identical offline.
How accurate are the results?
Conversions use the exact defined values rather than rounded ones — an inch is 0.0254 m, a pound is 0.45359237 kg, a US gallon is 3.785411784 L. Results display up to six significant digits, which is more precision than any of these measurements carry in practice.
What exactly is in the professional pack?
Thirteen industry categories — pressure, torque, power, force, thermal conductivity, stress, baking, nautical distance and speed, textile yarn count, precious metal, print and typography, energy — plus batch conversion with CSV export, custom unit formulas, and history export.
Can I switch it to Chinese? What about dark mode?
Settings switches the interface between Chinese and English instantly, and appearance follows the system or stays light or dark if you prefer. Both languages ship in the same download.
I bought it before. How do I get it back?
Tap Restore Purchase in Settings, or on the premium screen. It uses the Apple ID you bought with, so it works on any device signed in to the same account.