Support

UnitSwap mobile app

Frequently asked questions

What do I get for free?

All everyday unit conversion is free and unlimited: length, weight (including jin), area (including mu), volume (US/UK gallons), temperature, time, speed, plus the amount-to-Chinese-uppercase tool. History, favorites, and all conversion features run entirely on your device — no account needed.

What does the Premium Pack include?

A one-time, buy-forever unlock of 13 industry categories — pressure, torque, power, force, thermal conductivity, stress, baking volumes, nautical distance and speed, textile counts, jewelry weights, print/DPI units, and energy — plus batch conversion, custom units, and history export to text/CSV.

Does the app need internet access?

No. UnitSwap works fully offline. The only time any network is used is when you purchase or restore the Premium Pack, which is handled by Apple's In-App Purchase system.

Is the Premium Pack a subscription?

No. It is a one-time, non-consumable purchase. Buy once and it is yours forever on all devices signed into the same Apple ID.

How do I unlock Premium on a new device?

Install UnitSwap on the new device with the same Apple ID, then go to Settings → Premium Pack → Restore Purchases (or the Restore link on the paywall). Your purchase is re-validated with Apple at no extra cost.

I purchased but the Premium features are still locked.

1. Make sure you are signed into the same Apple ID used for the purchase.
2. Tap Restore Purchases in Settings or on the paywall and wait a few seconds.
3. Restart the app and try again.
4. Still stuck? Email us with the purchase date and Apple's order confirmation email — we'll sort it out.

How do refunds work?

Purchases are billed by Apple. To request a refund, contact Apple at reportaproblem.apple.com. Once Apple approves the refund, the Premium features are re-locked.

Where is my data stored?

Everything — your conversion history (last 10 entries), favorite pairs, custom units, and settings — is stored only on your device. Nothing is uploaded anywhere; uninstalling the app deletes it all. See our Privacy Policy.

How do I clear my history?

History tab → Clear (top left), or Settings → Data → Clear History. Only the 10 most recent conversions are ever stored.

Can I add my own units?

Yes, with the Premium Pack. Custom Units lets you define a formula as "1 [your unit] = X [base unit]" (e.g. 1 斤 = 0.5 kg) and it then appears in that category's conversion list like any built-in unit.

A conversion looks wrong, or I need a unit that isn't listed.

Tell us! Email the category, the units, and the expected result, and we will fix or add it in the next update.