NMA Calculation

I am looking over my deed and lease agreement and had a question regarding the calculation used to derive my NMA. I'd appreciate any input.

BTW, the actual particulars are:

An undivided twenty/three hundred twenty eights (20/328). Royalty is 25% (1/4). The decimal is .01524



Hi Robert -

1 divided by 328 times 20 divided by 4 = 0.0152439024 or 0.01524 rounded.

[1/328 x 20 /4 (or x 0.25) = 0.0152439024]

If your lands are pooled with other lands, your ultimate decimal will also be adjusted by the acreage ratio of your lands to the entire unit.

Your Division Order will typically take the Decimal Interests to one or more places further out than the Mineral Tax Rolls will.

Hope this helps -

Charles Emery Tooke III

Certified Professional Landman

Fort Worth, Texas

Dear Mr. Montgomery,

NMA means Net Mineral Acres. You cannot compute your Net Mineral Acres until you disclose your Gross Acres in the tract.

For example, if you owned a 20/328 interest in 226 gross acres, you would then own 13.78048780487805 Net Mineral Acres (NMA).

If, for example, you signed a lease that provided for a 25% royalty and your lands were not pooled with others, your share of production would be the decimal interest that you computed above.

BUT, to answer your question about Net Mineral Acres, we don't know enough to tell you the answer.

If you are looking to confirm a division of interest on a Division Order, we still do not have all of the information.

To learn more about calculating your share of production in a well, see here:


There is a downloadable worksheet attached to the blog post.


Buddy Cotten

The drilling unit on the lease shows 656 acres.

My deed says twenty/three hundred twenty eights (20/328) interest in all of the west half of section XX, in Block X-X, containing 328 acres. Royalty on lease is 1/4

My decimal is .01524390

Thanks for the responses


Dear Mr. Montgomery,

You say that the "drilling unit on the lease shows 656 acres." That is past unusual that a drilling unit would be specified on an oil and gas lease.

I am going to hope that you meant that there is a pooled unit of 656 acres.

Taking everything that you have said at face value, it appears that you have a 20 Net Mineral Acre interest in a POOLED UNIT -- not drilling unit.

A discussion of the various types of units in Texas are discussed here:


With the assumption above that a pooled unit was formed to be 656 acres in size. Assuming that you have no burdens against your royalty interest, your share of production should be:

20/656*.25, or a decimal interest of 0.00762195. If a well was brought in that averaged 1000 bopd over a 30 day period, your share of production would be 228.68 bbls of oil. If the average sales price was $45 for that 30 days of oil sales, then your gross share of production would be $10,289.63.

Taxes and perhaps operating costs would be deducted from that figure. An interpretation of the lease terms would be in order to know for sure.

This can be easily calculated from the division order spreadsheet which I gave a link to on my earlier response.


Buddy Cotten