# Re: [Snowdrift-discuss] How the limit works

``` On 08/09/2016 11:20 AM, Bryan Richter wrote:

> <snip>
> There are three things being discussed here, so I want to provide
> space to think about them separately.
>
> <snip>
>
> Finally, how is the minimum sensible pledge displayed: as a dollar
> amount, or as a ratio? I think it's clear that the amount should be
> *calculated* as a ratio, but I'm not certain that *displaying* it as a
> ratio is best. But I don't actually know. Any opinions here?
>
> I'm personally partial to dollar amounts because it provides an
> (algorithmic) level of indirection. If we say we charge <=10%, and
> then Stripe changes its fees faster than we can adapt, we'd be lying.
> But if we say, "We won't charge you for amounts less than 2 bucks",
> that's totally within our control. We would simply use the ratio as a
> rough guide for future corrections.```
```
This makes sense to me.  However, if we're displaying a dollar amount I
do think we do need to round it at least to a quarter or half dollar, so
it doesn't seem mysteriously arbitrary.  For example, since \$3.66
corresponds to just under 10%, if we use dollar amounts, I'd suggest
\$3.75 or \$3.50.  Then in future if we support multiple payment
processors, they could have different minimums if necessary, which could
also be changed if they change their fees.  I think dollar amounts are
easier for the user to understand in terms of knowing what determines
whether they're charged in a given month, so I'd favor dollar amounts
provided we round to at least a quarter.  In this case we're using the
ratio calculation in order to decide on a sensible rounded minimum
dollar charge, and then allowing the maximum percentage to be a weird
arbitrary number that we don't present to users. For example if the
minimum charge for Stripe is \$3.50 then with their current charges, the
maximum percentage is about 11.2%.  I think that's fine as long as we
don't talk about percentages to the user.  In other words, I think we
either say something like "Minimum charge is \$3.50" (but don't make it
\$3.66) or something like "Maximum percentage is 10%" (but don't make it
11.2%).

```

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