Frequency extracted from MATLAB's $\tt fft$ is not very accurate

1. How can I make my FFT more accurate?
2. What is FFT length?

How can I make my FFT more accurate?

The most intuitive way to increase the frequency resolution of an FFT is to increase the size while keeping the sampling frequency constant. Doing this will increase the number of frequency bins that are created, decreasing the frequency difference between each.

What is FFT length?

The FFT size defines the number of bins used for dividing the window into equal strips, or bins. Hence, a bin is a spectrum sample , and defines the frequency resolution of the window. By default : N (Bins) = FFT Size/2.