It's not about
how much you pay off each month at all. The banks don't calculate credit scores—the credit reporting agencies do. And the credit-reporting agencies don't think that way.
The thing about credit event streams is that they're very low-detail: basically they amount to, for each credit instrument you have, a series of {pay-period, code} pairs with nine possible codes, R1-R9. Your score is entirely calculated† by taking (a seven-year sliding window of) those event-codes and applying weights to them. R1, the most-positively-weighted event, just means "paid on time this month."
The thing you want to do to build good credit quickly, is to generate as many R1 events as you can. You can carry some of your debt on a card to "stretch" one large charge into multiple R1 events... but a more efficient strategy (that doesn't involve paying any interest) is to simply have several cards, use them all for at least one trifling thing each month, and then pay them all off each month. Three cards you paid off $5 charges on is three R1s, and counts for just as much as one $500 charge you paid in three instalments (also three R1s.)
If you want to dig in and see exactly how much information a CRA will give you, here's a Ruby implementation of the Experian Connect API: https://github.com/ehutzelman/experian
---
† Well, okay, there's also two other things:
1. a positively-weighted factor for how much unused credit each instrument holds each month. Which usually translates to "you get punished for carrying an 80%+ balance on a credit card." The key with this one is that—all else being equal—it's better to have cards with higher credit limits, because then you're not using as much of each instrument's capacity, and that reflects better on you.
2. a negatively-weighted factor for any "hard inquiries" that the credit-reporting agency had to respond to within some time window. Each time you apply for a credit instrument and the loaning institution asks the reporting agency to calculate your credit score for the purpose of determining credit eligibility, that's a "hard inquiry" event. (You can think of these as their own credit event on a "meta" instrument held by the reporting agency itself.) Unlike normal credit instruments, there are no industry standards on how to set the weights or time-window for the effects of "hard inquiries", but the windows are usually short (~6 months), AFAIK. All else being equal, don't quickly, repeatedly apply for credit: each successive loaning institution will see a lower score. (And note the "for the purpose of determining credit eligibility" bit. There's another kind of event, a "soft inquiry", that happens when you—or some third-party on your behalf—just asks the reporting agency for your credit score in order to know it, or background-check you, or whatever else. I'm pretty sure none of the big three CRAs in the US give any weight to a "soft inquiry" event.)