Desirable sperm count to perform IUI is between 20 million/ml to 30 million/ml. If it is lesser than this then IVF will be the best suited treatment. Apart from the sperm count, 50% of the sperm sample should be motile to perform an IUI cycle.
Sperm count in the normal range is required for successful pregnancy. The minimum sperm count is 20 million/ml. You can get a semen analysis test done to find out the sperm count, so that you can start with the IUI procedure.