Every royalty check you receive is built on one number: a decimal, usually eight places long, printed on your division order. That decimal is your net revenue interest in the well. Multiply it by what the well sold that month and you have your check, before taxes and any deductions. If that sentence just gave you a flashback to high school pre-calculus, relax. The whole thing is three multiplications, and there is a calculator at the end that does them for you.
You can own 100% of the minerals under a tract and still have a net revenue interest well under 1%, because the well draws from a whole unit and you receive only the royalty share of your part of it. Most Oklahoma mineral owners never check that decimal. They sign the division order, the checks arrive, and the number is taken on faith. That is a mistake, because the decimal is the product of three inputs that are easy to get wrong, and a small error repeats every month for the life of the well. This guide shows you where each input comes from, how to do the math yourself, and how to catch the common errors.
Net revenue interest is not the same as owning minerals. You can own 100% of the minerals under a tract and still have a net revenue interest well under 1%, because the well draws from a whole unit and you receive only the royalty share of your part of it.
What Is Net Revenue Interest?
Net revenue interest (NRI) is the fraction of a well's production revenue that a particular owner is entitled to receive. It is expressed as a decimal, and the decimals in a well add up to exactly 1.
The well's revenue splits into two layers:
The royalty layer. Mineral owners who leased their minerals, or who were pooled by the Oklahoma Corporation Commission, receive a royalty share of production. They pay none of the drilling or operating costs. Their NRI is their royalty share of their part of the unit.
The working interest layer. The operator and any partners who paid to drill the well hold the working interest. Their NRI is what is left after every royalty, overriding royalty and other burden has been paid out. A company with a 100% working interest in a well burdened by a 3/16 royalty has an 81.25% net revenue interest.
Both layers use the same vocabulary, which is why a search for "net revenue interest" turns up both landman spreadsheets and royalty-owner questions. This guide is written for the royalty side, which is where most Oklahoma mineral owners sit. The working interest math is covered briefly near the end.
The Three Inputs
Your royalty decimal depends on three things, and you need all three before you can check it.
1. Net mineral acres
Gross acreage is the size of the tract described in your deed. Net mineral acres (NMA) is the share of the minerals under that tract that you actually own.
If you own an undivided one-half of the minerals under a 160-acre quarter section, you have 80 net mineral acres. If you own one-eighth of the minerals under 40 acres, you have 5 net mineral acres.
This is the number that most often goes wrong, especially with inherited minerals. A grandparent's 160 net acres divided among four children, then among their children, produces fractions like 1/24 and 5/96 that are easy to miscopy. If your minerals came to you through an estate, the inherited mineral rights guide explains how to trace the chain of title that produces your fraction.
2. Unit size
In Oklahoma, a well does not pay only the tract it sits on. The Corporation Commission establishes a drilling and spacing unit, and every mineral owner in that unit shares in the well in proportion to their acreage. Most horizontal wells in the STACK, SCOOP and Merge plays sit in 640-acre units, one full section. Older vertical wells often sit in 40-, 80- or 160-acre units.
Your share of the unit is your net mineral acres divided by the unit's acres.
Ten net mineral acres in a 640-acre unit is a 1.5625% share (10 ÷ 640 = 0.015625). The same ten acres in a 160-acre unit is a 6.25% share. Unit size is set by a spacing order, which is on file at the OCC, and it is one of the first things to verify when a decimal looks wrong. The OCC records guide shows where to find spacing orders by section, township and range.
3. Royalty rate
Your royalty is the fraction of production you receive without paying costs. It comes from one of two places:
Your lease. The royalty clause states the fraction: 1/8, 3/16, 1/5 or 1/4 are the common ones in Oklahoma.
A pooling order. If you never leased and the operator pooled you, the Corporation Commission's order gives you a menu of options, each with a bonus and a royalty. The royalty you elected is your royalty for that well. The pooling orders guide walks through those options.
Older leases in Oklahoma are often 1/8 (0.125). Leases and pooling elections since the shale era are usually 3/16 (0.1875) or higher. If your family has held minerals since the 1950s, the lease still in force may carry the older rate, and no later well changes it unless the lease has expired and been replaced.
The Formula
Put the three inputs together:
That is the whole formula for a royalty owner in a single-section unit. Everything else in this guide is about getting the inputs right and handling the two Oklahoma wrinkles below.
A Worked Example
Say you inherited an undivided one-quarter interest in the minerals under a 40-acre tract in Kingfisher County. An operator leased you at 3/16 and drilled a horizontal well in a 640-acre unit covering the whole section.
Step 1: net mineral acres.
40 gross acres × 1/4 = 10 net mineral acres
Step 2: unit share.
10 ÷ 640 = 0.015625
Step 3: apply the royalty.
0.015625 × 0.1875 = 0.0029296875
Your division order should read 0.00292969 (eight places, rounded). That is your net revenue interest in the well.
What it means in dollars. Suppose the well sells 15,000 barrels of oil in a month at $70, for $1,050,000 in oil revenue.
$1,050,000 × 0.0029296875 = $3,076.17
Gas and natural gas liquids are added the same way, each at its own price, and the operator may deduct gross production tax (7% in Oklahoma, reduced to 5% for the first 36 months of production on wells drilled since 2015) and, depending on your lease, some post-production costs. Your check stub shows each product and each deduction separately.
The Mineral Watch mineral calculator takes gross acres, your fraction, unit size and royalty and returns your decimal and an estimated monthly check. It is free and does not require an account.
Wrinkle One: Multi-Unit Horizontal Wells
Modern Oklahoma horizontal wells often run two miles or more and cross more than one section. Under the Extended Horizontal Well Development Act, the Corporation Commission can approve a multi-unit horizontal well, and the order allocates production among the units it crosses, usually by the length of the completed lateral in each section.
If a 10,000-foot lateral has 6,000 feet completed in your section and 4,000 feet in the section to the north, your section's allocation factor is 60%. Your decimal in that well is your single-unit decimal multiplied by the allocation factor.
Using the example above: 0.0029296875 × 0.60 = 0.0017578125
This is the single most common reason a decimal looks "too small" to an owner who did the math for a full section. The allocation percentages are stated in the OCC's multi-unit order and are repeated on the completion report. If your division order decimal is close to but below your single-unit math, look for an allocation factor before you assume an error.
Wrinkle Two: Net Royalty Acres
If you have received an offer to buy your minerals, it may be priced per net royalty acre (NRA) rather than per net mineral acre. The two are related but not the same, and buyers sometimes rely on owners not knowing the difference.
A net royalty acre is defined as the royalty equivalent of one net mineral acre leased at a 1/8 royalty. To convert:
Ten net mineral acres leased at 3/16 is 15 net royalty acres (10 × 0.1875 ÷ 0.125 = 15). Ten net mineral acres leased at 1/4 is 20 net royalty acres. Ten net mineral acres that are unleased are usually quoted as 10 net royalty acres by convention, though an unleased owner's eventual royalty could be higher or lower.
Why it matters. An offer of $3,000 per net royalty acre on your 10 acres at 3/16 is $45,000. The same offer quoted per net mineral acre would be $30,000. Before comparing two offers, convert both to the same unit, and check which royalty the buyer assumed in the conversion.
How to Check the Decimal on Your Division Order
A division order is the operator's statement of what it believes your decimal to be. Oklahoma's Production Revenue Standards Act requires the operator to begin paying you within six months of first sale, with interest if it is late, and the statute does not make a signed division order a condition of payment; the only recognized reason to hold your proceeds is a title problem. Signing confirms the decimal; it does not create it.
Pull the three inputs from documents, not memory.
- Your net mineral acres, from your deed or the probate decree that vested them in you.
- The unit size, from the OCC spacing order for the section (or the multi-unit order, if there is one).
- Your royalty, from your lease or your pooling election.
Run the formula. Multiply the unit share by the royalty, and by the allocation factor if the well is a multi-unit horizontal.
Compare to eight places. Operators round the decimal to eight places. If your math gives 0.0029296875 and the division order reads 0.00292969, that is agreement. If it reads 0.00195313, something is off: in that case the operator used a 1/8 royalty instead of 3/16, which is the most common mismatch on older leases that were later amended or replaced.
If the numbers disagree, write to the operator's division order department with your math and copies of the deed, lease and spacing order. Operators correct decimals routinely; what they will not do is go looking for errors in your favor.
Mineral Watch does this part for you. When a division order or check stub is uploaded to your Mineral Watch account, the decimal is read from the document and stored on the well, so you can compare the operator's number against your acreage and royalty, and against what other operators paid you on neighboring wells. Start free.
Mistakes That Change the Decimal
Using gross acres instead of net. An owner with 40 gross acres but a one-quarter interest has 10 net mineral acres, not 40. Running 40 through the formula overstates the decimal fourfold.
Using the tract size instead of the unit size. The well pays the whole spacing unit, not your tract. Dividing by 40 instead of 640 overstates the decimal sixteenfold.
Forgetting the allocation factor. Covered above. On a multi-unit horizontal well, your decimal is scaled by the share of the lateral completed in your section.
Applying the wrong royalty. Family leases from the 1960s often carry 1/8. A pooling order you elected in 2022 may carry 3/16 or 1/5. Each well is paid on whichever instrument governs that tract for that well.
Stacked family fractions. If your mother held 1/6 of 1/2 of the minerals, you hold 1/12 of the minerals, not 1/6 and not 1/2. Write the chain out and multiply the fractions all the way down. The inherited mineral rights guide covers how to document each step.
A deduction mistaken for a decimal error. If your decimal is right but your check is smaller than expected, the difference is usually gross production tax or post-production costs, not the decimal. Oklahoma courts have generally held that the lessee bears the cost of making gas marketable, while costs incurred after that point may be shared depending on the lease language. The royalty check audit guide shows how to read those deductions line by line.
The Working Interest Side, Briefly
If you participated in a well as a working interest owner, or elected to participate under a pooling order, your net revenue interest is calculated differently:
A 100% working interest in a well where every tract is burdened by a 3/16 royalty has a net revenue interest of 81.25%. A 10% working interest in that well has an 8.125% net revenue interest. If an overriding royalty of 2% has also been carved out of the working interest, the burdens total 20.75% and the 100% working interest's NRI falls to 79.25%.
The two percentages are different on purpose. A working interest owner pays its working-interest share of the costs (10% of the drilling and operating bills in this example) but receives only its net-revenue share of the sales (8.125%). The royalty owners are paid off the top first; the gap between the two numbers is their royalty. That is why the royalty owner's smaller decimal is often the better deal per acre. The pooling orders guide compares the two paths when you have a choice.
Frequently Asked Questions
It is the fraction of a well's sales that belongs to you. For a royalty owner it is your net mineral acres divided by the unit's acres, times your royalty rate. It is printed on your division order as an eight-place decimal.
Multiply the tract's gross acres by the fraction of the minerals you own. 160 gross acres with a one-half mineral interest is 80 net mineral acres. The fraction comes from your deed or probate decree.
Net mineral acres measure what you own. Net royalty acres measure what you earn, standardized to a 1/8 royalty. Ten net mineral acres leased at 3/16 are 15 net royalty acres. Buyers often price offers per net royalty acre.
Decimal interest is the same thing as net revenue interest, written as a decimal. Operators and division orders use the term interchangeably with NRI.
Four usual reasons: the well is a multi-unit horizontal and your section receives only part of the lateral; the unit is larger than you assumed; the operator is paying on a 1/8 lease rather than the 3/16 you expected; or, with inherited minerals, the probate conveyed a smaller fraction than the family assumed, so the operator's title opinion carries fewer net acres than your deed math. Check all four before writing to the operator.
Yes. The Mineral Watch mineral calculator takes gross acres, your fractional interest, unit size, royalty and an optional allocation factor, and returns your decimal and an estimated monthly check at a price you choose.
The Bottom Line
Your net revenue interest is three numbers multiplied together: your net mineral acres divided by the unit's acres, times your royalty. On a multi-unit horizontal well, multiply once more by your section's share of the lateral. Every one of those inputs lives in a document you can get: your deed, the OCC spacing order, and your lease or pooling election.
Check the decimal once, when the division order arrives, and you will know for the life of the well whether you are being paid on the right number. Run your numbers in the free calculator, and if the operator's decimal disagrees with yours, you will have the math to show them.