**Would it be fair to use 1d30 – in place of 2d20 and taking the higher die – for advantage rolls?**

Recently I have acquired several d30 dice in a bag of factory seconds. I want to offer my players the option of using a d30 dice instead of using 2d20 dice for Advantage rolls.

The idea is that the d30 is meant to be a high-risk, high-reward option in that you have more chances to roll a high number but, as you are only rolling one dice, there is presumably more risk due to not having an option to take the highest of two rolls.

Whilst I can not find anywhere on the internet that discusses such a situation (most discussions about d30’s boil down to using them for 30-entry tables), I have found probabilities for the dice.

AnyDice is a free website that allows you to calculate the probabilities of rolling any dice and can display the results in various formats. Below are screenshots taken of the probabilities for both 1d30 and 2d20 (take the highest result) to get *at least* X number:

1d30:

1d20 (taking the highest result):

Based on this data, I want to know if it would be fair to use 1d30 in place of 2d20. By “fair” I mean whether the advantage of the d30 (there being more chances to pass any DC check due to it having higher numbers) would be balanced out by its disadvantage (the lack of an option to take the highest result of two rolls).

The best answers should, using data and examples, explain why using 1d30 instead of 2d20 (take the highest result) is either balanced or unbalanced.