Macro for Bardic Inspiration 1dX progression

I do not know a good macro to make a ceiling for how high a number can go. PHB only allows for progression of d6 d8 d10 and d12. My friends and I play D&D 5e using OGL sheet, and we like to use macros in the Personalities and Traits section. I came up with this to use for showing off the Bardic Inspiration You can inspire others through stirring words or music. To do so, you use a **Bonus Action on Your Turn** to choose one creature other than yourself within 60 feet of you who can hear you. That creature gains one Bardic Inspiration die, a 1d[[(round(@{base_level}/5+0.5)*2)+4]]. Once within the next 10 minutes, the creature can roll the die and add the number rolled to one **Skill Check**, **Attack Roll**, or **Saving Throw** it makes. The creature can wait until after it rolls the d20 before deciding to use the Bardic Inspiration die, but must decide before the DM says whether the roll succeeds or fails. Once the Bardic Inspiration die is rolled, it is lost. A creature can have only one Bardic Inspiration die at a time. You can use this feature a number of times equal to [[@{charisma_mod}]] (a minimum of once). You regain any expended uses when you finish a Long Rest. It will automatically update the Bardic Die size, but I dont know how to cap it, in case of a 20th level character, as that would update to a 1d14 instead. Can anyone help?

Change the 1d formula to 1d[[{(round(@{base_level}/5+0.5)*2)+4,12}kl1]] If the formula, as it seems, increases every 5th level, you can change the round function to floor, like so: 1d[[{(floor(@{base_level}/5)*2)+4,12}kl1]] which makes it a little smoother.

Ok cool. Do you mind explaining what ,12}kl1 does, so I know how to use that in the future for other macros?

the kl stands for keep lowest, so when you have something like {number,another number}kl1 it will keep the lowest of those two numbers. The curly brackets make it a group, and kl and kh (keep highest) compare those against each other. A pitfall with these is you can't mix dice with numbers, so if you have a combination, you have to convert numbers to dice by adding "+0d0" to the number - roll20 then treats this as a dice roll. For example, say you wanted to roll d6-2 three times, take the highest, with a minimum of one, you'd write that as {1d6-2,1d6-2,1d6-2,1+0d0}kh1 And you can use kh or kl without a group {}. Say you were rolling 4d6, and keeping the best 3, you'd write that simply as /roll 4d6kh3 These are described on the  dice reference page.

By the way, i just reaxamined your formula, and it looks like the floor version I suggested would be incorrect.

Ah for dice rolls we always just use [[4d6k3]] or [[4d6d1]]