Around 1/3 players use online BG calculators. 

Here are some

Has n option to sing in. Possibly owned by KoK

Made by destiny player looong time ago

Used by many top BG players. Many in emps. Not sure who made it. Its very accurate if you know how to input your bonuses correctly. Recently ported to ru and is available for most plarium games.

Supper great. I recommend this. After you understand it just make your own version.

Lord mark has another 

I never saw much point in having a calculator.  The more you play bgs the more you lose to the tax, so just do them as little as you can to convert junk troops into the type you want. 

If you do use one, just be careful downloading files off the internet :)

There really is no need for a calculator. If you are playing BG's "normally" and regularly then there are no strategies that max or min your rate of reward. The tax is the tax no matter how you play them.

So for the amount of time and effort needed to keep typing your troop losses and payouts into a spreadsheet, the only upside is being able to predict when you will get a payout. You can just hit them, until you get a payout at a fraction of the time and effort, for exactly the same net gain/loss.

You could try using a calculator that handles detailed data inputs—might help you keep track of your BGS bank resources more clearly, especially if you're juggling multiple high-level games. Worth a look if you're unsure whether your bank is full or not.

Yes he was asking for a spreadsheet or other tool to facilitate that.  2 years ago...

Someone still doesn't use a calculator and likes to see some surprise payment from battlegrounds😎

And i have to admit also that even if you will use a calculator you will never have a certain of 100 % avout the statistics what you put  and what you receive .

Good game to everyone , on this old thread from 2018  👻

Yeah I found that using a calculator wasn't really worth the effort.