Apparently not everyone always takes a ruler, protractor or spirit level in pocket. But if you want to measures something, the following measuring app Multi Measures should be able to help you.
Multi Measures is an all-in-one measuring tool kit developed by SkyPaw, and designed for iPhone and iPod touch. The iPhone app features intuitive and graphical user intuitive, and comes with 10 practical measuring tools including teslameter, metronome, stopwatch, timer, seismometer, plumb bob, surface level, spirit level, and ruler. Via the intuitive dial and icons, you can quickly select the measuring tool that you need, and each measuring tool also features intuitive interface, moreover, the locker for every tool allows you to more conveniently measure your object.
Multi Measures with a size of 14.3 MB is compatible with iPhone, iPod touch and iPad running iOS 3.0 or later. The iPhone app is free for a limited time at present. If you’re interested, jump to App Store for more details.