BabelUnits

BabelUnits Calculator is a simple to use and elegant unit conversion and reference calculator. With a description to help one understand every unit.
Now with accessibility for the visually impaired. The calculator and units are now VoiceOver capable. With VoiceOver activated each button, each unit, the number fields, and each action all have audio descriptions in English and haptic cues.
It includes a powerful calculator with natural logarithms, natural exponents, logarithms with any base, exponents of any real number. Memory buffer with M+ and M- functions. Statistical entries with mean, median, and standard deviations with and without bias. Trigonometric functions and their inverses for sine, cos, and tangent and their corresponding hyperbolic functions and their inverses.
In addition to the more common conversions, BabelUnits includes many fun and point-of-reference conversions: find your weight on Mars, compare heights with the Eiffel Tower or the Burj Khalifa, or compare a vehicle's speed compared to a jet's Mach index or the speed of light. Even sports units! With 35 different conversion categories and thousands of units, BabelUnits provides a complete solution for any engineer, student, professional, archivist, or just curious individual that needs an instant conversion.
International units are included as well. Common units from Australia, China, Egypt, Germany, Japan, India, Korea, Scotland, Cyrillic, the United Kingdom, and the United States can be found in all categories. Even archaic units from ancient Rome, ancient Israel, or the Egyptian kingdoms can be used.
BabelUnits is ad free! And... we do not collect your information at all. Use BabelUnits with peace of mind knowing that nothing is happening to your precious personal info.
BabelUnits's current conversion categories are:
Angle (planar and solid),  
Area, 
Area (Basic),
Area (Real Estate),
Bolt Sizes,
Charge, 
Construction (Lengths),
Construction (Volumes),
Cooking (Mass),
Cooking (Volume),
Current (Electrical),
Density (mass per volume)
Distance, 
Distance (Astronomy),
Distance (Basic),
Distance (Fun),
Distance (Sports),
Energy, 
Energy (Batteries),
Flow (Volumetric), 
Flow (Mass),
Force, 
Frequency, 
Illuminance, 
Jerk, (Change in Acceleration per unit time)
Lengths,
Length (Industrial),
Length (Machine Shop)
Luminance, 
Luminous Intensity, 
Magnetic Field Strength, 
Magnetic Flux Density, 
Mass, 
Mass (Astro),
Mass (Basic),
Nautical Distance,
Powers, 
Power Ratios for 50Ω, 75Ω, 8Ω, and 32Ω system impedances, 
Pressure, 
Radioactivity, 
Radioactivity Dosage, 
Radioactivity Dosage Equivalents, 
Temperature, 
Time, 
Torque, 
Velocity, 
Viscosities Kinematic, 
Viscosities Dynamic, 
Volume,
Volume (fluid),
and Weights.
To copy the converted value you can share using the share button in the bottom second-from-left of the keypad or simply tap the converted value to copy the number into the clipboard. Any localized number value in the clipboard can be pasted into the top number field by simply tapping the field once.
iPad:
BabelUnits works well with other iPad apps. It can be used as a slider or separate floating window on iPad. Copy and paste from one app to BabelUnits. Just touch the input field to paste a copied number and touch the output field to copy the conversion value to another app.