How do I determine the appropriate number of cycles in PCR?

The cycling of PCR depends mainly on the amount of DNA input and the desired yield of the target PCR product. If your DNA template is of good quality, you can choose fewer cycles, and if the DNA starting amount is less than 10 copies, it may take up to 40 cycles to get enough product. However, considering the characteristics of the enzyme, it is best not to set more than 45 cycles, the high fidelity of the enzyme will be reduced when the number of cycles is too much, it is easy to mismatch, and it is easy to produce non-specific bands. In general, I set 32 cycles when I perform DNA amplification, and when the concentration of DNA template is too low, I will concentrate and purify it before amplifying.