We calculate the cover fee using 2.2% + $0.30 as the base rate because it's not possible to know exactly what rate your Stripe/PayPal account is on (ie. you might be on a special discounted NPO rate, etc). Therefore, 2.2% + $0.30 is the lowest and safest rate where the fee being taken is not more than is needed.
We also include the Donorbox fee (1.5%), because we have no way of knowing if you will reach the $1,000 limit or not. If you do, you will already have the 1.5%. If you don't, you can refund that portion back to the donor.
When a donor opts to cover the processing fee, the entire donation amount has now increased (original amount + processing fee). This is a small amount but adds up to about $1.38 for every $1,000 - our system uses a formula to calculate this.
Consequently, the fees will be slightly more than for a straightforward $100 donation, for example.
The extra fees added for the donor to cover on a $100 donation is calculated as follows:
$2.59 (2.2% + $0.30 of now increased donation amount) Stripe/PayPal fee
+ $1.56 (1.5% of now increased donation amount) Donorbox fee
$4.15 (Total fees charged)