Figuring Decimal Interest and royalty check

I am in the process of getting my fathers mineral rights put into my name. Just curious as to how to figure the decimal interest and amount of royalty check. Could someone just help me with Scenario.

Well produces 18000 barrels for the month

Oil price is lets say 90 / Barrell

I have 1/12 interest in 180 net mineral acres in a 1280 acre spacing unit

How would I figure out the decimal interest and royalty check amount.

Any help would be greatyly appreciated.

What is the royalty percent on the lease?

If the lease was signed for 3/16 of production you would get .1875 of the total or $303,750.00

I came up with considerably less. 18,000 X $90 = $1,620,000 divided by 1280 = $1265.62 X 15 acres [ 180 acres divided by 12 ] =18,984 now you have to plug in your royalty @ 20% = $ 3,797, at 3/16 {.1875%} = $3,560. I rounded off the pennies. If you have a different royalty percentage you will have to use it instead of the examples I gave. This is not including 11.5% production and severance tax, ND state income tax up to 4%, federal tax, post production or marketing costs. What you actually get to keep is going to be far lower than the calculated amounts above. If you keep 70% you are doing very well. I would also caution you that my oil that is a very good grade and usually draws a premium was selling for $81 last november and almost $84 in December. The oil is in ND but the refineries are elsewhere. Transportation costs drive the price down. It is also a crap shoot that your operator will make a good deal on the sale, sometimes they sell oil for more than I expected and sometimes far less. Do not, count on your well to produce every day of the month, or even every month or that the price of oil will stay the same. Make plans for what you will do with it but don't count on it being there.