The minimum amount of Bitcoin you can buy varies depending on the exchange or broker you use and the payment method you choose. Generally, most exchanges and brokers require a minimum purchase amount of $10 to $25 for credit or debit card payments. If you are using a bank account, the minimum purchase amount may be higher, usually around $50.
The minimum purchase amount may also depend on the type of order you are placing. For example, if you are placing a limit order, the amount you can buy may be limited to the amount of Bitcoin available at the desired price. Alternatively, if you are placing a market order, you may be able to buy any amount of Bitcoin up to the total amount available in the market.
In addition, some exchanges and brokers may require a minimum purchase amount when using certain payment methods or when creating an account. For example, some exchanges may require a minimum purchase amount of $100 when creating an account.
It is important to note that the minimum purchase amount may also vary depending on the country you are in. Some countries may have different regulations that affect the minimum purchase amount. It is always best to check with the exchange or broker you are using to make sure you are aware of any country-specific regulations.