How much money counts as a minimum for a payment online?

That depends entirely on the website, but there is a percentage that is sometimes required by specific online stores and banks as a minimum payment. If it is a credit card payment you are inquiring about, the information is always stated in the registration records of your card. Most cards offer a minimum of 15-25 dollars depending on the balance. Some websites allow you to do flexible payments of 25% of the total value of the product to be paid in installments. Ultimately, it will be the decision of the merchant to make the final amount.