Bringing alcohol outside EU into Finland

Hi I am traveling to Japan soon and would like to bring back alcohol more than the allowed limit and I am looking for a formula to calculate how to pay for duty/tax/fee. I tried Tulli support both phone and email and they were…: you will know when you return 🤡

  1. Do I only have to pay for the volume that is over the limit?
  2. If yes, do they calculate it based on volume or bottle?
  3. If you know a sure fire way to calculate it, id be super grateful to learn the break down.

Context; I am trying to bring back around 3-4 litters of plum wine (~5-6 bottles). Its alcohol content is 8-10%. According to the law i can bring back 2L for free

Thanks, drunk connoisseur 🙏