How the minimum is actually calculated
Most US cards set the minimum as a percentage of the balance plus that month’s interest — commonly 1% of the balance plus the interest — but never less than a flat floor, typically $25. So on a $5,000 balance at 22.5% APR, the first month’s interest is about $93.75 and the minimum comes to roughly $143.75.
The floor matters when the balance is small: 1% of $1,000 plus interest is well under the $25 floor, so the floor becomes the payment until 1% plus interest climbs past it again. Both knobs are on this page so you can match what your own statement says.