I'm doing a project for that i need to measure capacitance.
But that capacitance is in the range of pico farad.
How to measure using arduino.
Please help me to choose the data type.


This one claims

About 1% accuracy, <2% error
Measuring range: 1pF - 500uF

And comes with a schematic.

Here is the schematic for my capacitance meter using a couple of 555 timers:

Basic idea: Make the capacitor under test part of a monostable circuit. Measure the pulse length. Subtract the pulse length when no capacitor is connected.

Just using 555 timers with a DMM on the 200mV scale, the lowest range can stably display capacitance down to 0.1pF. Accuracy and stability over time and temperature are pretty good, dependent on the temperature co-efficient and accuracy of the parts you are using and the accuracy of your reference capacitor.