Each conventional mortgage loan has its own down payments requirements, as they depend on the size of the loan. Such loans mostly require paying 20% down payment. For most buyers it’s quite difficult, as the size of the loan can be significant.
However, people buying their first homes can apply for a special program. (Know a bit more about how to buy your first home). It allows covering only a 3 to 5% down payment. The requirements of this program have improved, and now people with limited cash can also be approved for this loan. Thus, a 30-year fixed home loan with a 3% down payment is more attractive than the same one with a 5% down. But this type of loan has some extra requirements, such as high credit score and good credit history.
If you need a loan with a down payment lower than 20%, you will have to cover PMI or private mortgage insurance. This money is paid by a borrower to protect a lender in case you fail the repayment process.
Check the post about what does mortgage insurance cover to get a better understanding what it’s for.