Similar to the standard calculator app in Windows 10.
Add and subtract hours, minutes and seconds. Supports time formats HH:mm:ss and HH:mm. Switch between time formats using the menu button in the upper left corner.
Works on PC and mobile devices running Windows 10.
The app is totally free, but you can choose to support further development by purchasing a product in the settings page inside the app. Click the button below to download the app.