How to collect donations on a form?

I know how to add a choice for donations, but is there a way to add a short text box that they can enter in another amount themselves if they want. Can you also use this amount to calculate a total for paypal?

May we ask what payment processor you would like to use to collect donations? 

In general, there is an option to set 'Collect Donations' type of payment. It would add a textbox for users to enter amount:

Yes we will be using paypal. What I would like is to have a multiple choice with 5 different options for them, then at the bottom put a textbox for if they would like another amount. Is this possible?

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I see that you have used radio field with suggest donation amounts. You can try enabling 'other' option for users to enter custom amount:

Then, Form Calculation widget could capture the value entered:

Total from calculation widget can be passed to payment field afterwards: How-to-Pass-a-Calculation-to-a-Payment-Field

In case of PayPal integration, please use following help article: How-to-Integrate-Form-with-Paypal-Standard-

Let us know if you need more help.