Is your device running with iOS 7?
Yes. Have a look at iUnit 2!
iUnit 2 is especially designed for iOS 7!

iUnit let's you easily and intuitively convert hundreds of units in a total of 23 different categories.

Features:
⁃ iUnit places your favorite categories on a separate screen and allows you to arrange them as necessary.
⁃ The currency converter in iUnit loads the latest exchange rates automatically.
⁃ Copy values from iUnit and paste them into other applications (email, messages, calculator, etc.).
⁃ iUnit stores the last conversion of each category in the parent view, thus you can quickly look up older conversions.
⁃ iUnit is free of advertising.
⁃ iUnit is iPhone 4 and iPhone 5 optimized.
⁃ Turn keyboard sound on/off.

23 Categories (480 units):
⁃ Acceleration
⁃ Angle
⁃ Area
⁃ Currency
⁃ Amount of data
⁃ Data transfer
⁃ Density
⁃ Distance & Length
⁃ Electrical charge
⁃ Energy & Work
⁃ Flow rate
⁃ Force
⁃ Fuel consumption
⁃ Luminance
⁃ Mass & Weight
⁃ Power
⁃ Pressure
⁃ Radioactivity
⁃ Speed
⁃ Temperature
⁃ Time
⁃ Torque
⁃ Volume

I would be very thankful for your Feedback!
If you are missing units or categories, do not hesitate to send me an email!
iunit@denniswittke.com