joshd5166100 There is no separate sample size calculator for a non even split. However a few things to keep in mind are Your data is only as good as the smallest group, so 80-10-10 is really 10-10-10.Instead of using your full population, you could base it on the 'daily visitor' number you would get for your smaller experience. Alternatively if you reduced the total entrants and used an equal split, it would take the same amount of time and the normal traffic size calculator would work fine.
i.e. if 100 visitors came into your test, and the 80/10/10 split showed non-default to 20 people, you could allow only 30% of traffic into the test and then split it 33/33/33? This would still result in 20 people seeing non-default as an example.
If you have any further questions on the same, you could reach out to an Adobe business consultant on the same and they can provide more guidance on the same.