Decimoor by CyberMaxFor mineral & royalty owners, family trusts and landmen
Check every line of your royalty statement.
Work out your decimal interest step by step (pooled units, inherited shares like “1/3 of 1/4”, working-interest NRI), compare it with your division order, then check each statement line: volume × price × decimal, deductions and price against the monthly EIA benchmark.
- No sign-up
- Your data stays in your browser
- Free calculator, no limit
- Pro $9/month · $79/year
Free: decimal calculator unlimited, statement checks up to 5 lines per statement, 1 saved property.
- Math May oil: gross is $31.40 less than 1,920 bbl × $99.80 × decimal
- Deductions Jun gas: 38.0% of gross taken out
- Decimal Jul oil paid at 0.01634115, yours is 0.01640625
- Price Jul gas $1.62, 44% under Henry Hub $2.89
Fictional well; benchmark prices from the U.S. Energy Information Administration.
1 Your decimal interest
Royalty decimal = (net mineral acres ÷ gross tract acres) × royalty rate × (tract acres ÷ unit acres). In a pooled unit, add a row for each tract you own minerals in. Shares accept fractions such as 3/16, 1/8, 18.75% or chains like 1/3 of 1/4 for inherited interests.
Working interest? Net revenue interest (NRI) calculator
NRI = WI × (1 − lessor royalty − ORRI burdens).
2 Check a royalty statement
Type the lines from your check stub (one per well, product and month). Free: up to 5 lines per statement.
Loading monthly benchmark prices…
| Line | Volume × price | Their decimal | Gross paid | Expected at your decimal | Difference | Deductions | Net | Flags |
|---|
Real sample output
The built-in sample: a fictional owner inherits 1/3 of 1/4 of the minerals under a 160-acre tract (3/16 lease) and half the minerals under an 80-acre tract (1/5 lease), both pooled into a 640-acre unit. Decimal = 0.00390625 + 0.01250000 = 0.01640625; the division order says 0.01634115 (0.40% lower, flagged). Prices checked against EIA monthly benchmarks.
| Month | Product | Volume × price | Gross paid | Expected | Difference | Flag |
|---|---|---|---|---|---|---|
| 2026-05 | Oil | 1,920 bbl × $99.80 | $3,112.30 | $3,143.70 | -$31.40 | Math |
| 2026-06 | Oil | 1,850 bbl × $82.40 | $2,500.97 | $2,500.97 | $0.00 | OK |
| 2026-06 | Gas | 9,400 mcf × $2.61 | $402.51 | $402.51 | $0.00 | Deductions 38.0% |
| 2026-07 | Oil | 1,720 bbl × $78.95 | $2,219.03 | $2,227.87 | -$8.84 | Decimal −0.40% |
| 2026-07 | Gas | 8,900 mcf × $1.62 | $236.55 | $236.55 | $0.00 | Price −44% vs HH |
| Total, 5 lines | $8,471.36 | $8,511.60 | -$40.24 | 4 flagged | ||
Pricing
Free, no sign-up: the decimal-interest and NRI calculator with no limit, statement checks up to 5 lines per statement, and 1 saved property.
Free
- Decimal + NRI calculator, unlimited
- Division-order comparison
- Statement check, up to 5 lines per statement
- 1 saved property
- JSON backup
Pro yearly
$6.58 a month, one statement season to the next
- Unlimited statement lines
- Unlimited saved properties and wells
- CSV import and export
- Price flags vs EIA WTI / Henry Hub
- Printable owner report
- 14-day fix-or-refund if it doesn't work as described
- Cancel any time
- Secure card checkout by Stripe; your key appears right after payment
- Your data stays in your browser
How it compares (prices checked 9 Oct 2026)
| Product | Starting price | What it is |
|---|---|---|
| Decimoor Pro | $9/month · $79/year · $119 once | Statement checker + decimal and NRI calculator in your browser; free tier with no sign-up |
| MineralAnswers Plus | $29/month (Pro $59, Premium $129) | Mineral research and regulatory data platform |
| MineralTracker Pro | $99/month (reported, 2018 news report) | Mineral rights tracking service |
| MineralFile | From $500/month (Capterra listing) | Land and mineral management software for companies |
| Free decimal calculators | Free | Compute one decimal; no statement check |
FAQ
How is a royalty decimal interest calculated?
Royalty decimal = (net mineral acres ÷ gross tract acres) × royalty rate × (tract acres ÷ unit acres). If you inherited a share, net mineral acres = tract acres × your fraction of the minerals (for 1/3 of 1/4, that's 1/12). In a pooled unit you add the decimals of each tract. Decimoor shows every step so you can follow it or hand it to your landman.
Why not just use a free decimal calculator?
Free calculators work out one decimal. Decimoor also checks the whole statement line by line: whether volume × price × decimal matches the gross, whether net = gross − tax − deductions, how much is deducted, whether you were paid on the right decimal and whether the price is far below that month's benchmark.
Why not MineralAnswers, MineralTracker or MineralFile?
They are research and management platforms with monthly prices from $29 to $500 or more. If what you need is to check your own decimal and statements, Decimoor does that for $9 a month or $79 a year, with a free tier and no account.
Where is my data stored?
In your browser only (localStorage). Your properties, decimals and statement lines are never sent to our server. Export a JSON backup to move them to another device. The only network call is for the public EIA benchmark prices.
Is this advice?
No. Information tool only — not legal, tax, accounting or investment advice. Confirm your interest with your division order, lease and county records. A flag means “worth a question to the operator”, not proof of an underpayment: statements can differ for legitimate reasons such as prior-period adjustments, gas sold by the MMBtu, or lease clauses about deductions.
Where do the benchmark prices come from?
Monthly WTI crude oil spot (Cushing, OK, series RWTC) and Henry Hub natural gas spot (series RNGWHHD) from the U.S. Energy Information Administration open data API, last 36 months, refreshed every 12 hours. Henry Hub is quoted per MMBtu; your gas is often paid per mcf (1 mcf is about 1.04 MMBtu), and wellhead prices are normally below the hub, so set the price threshold to what is normal in your area.
What counts as a line?
One row of your statement: one well, one product, one production month. The free plan checks up to 5 lines at a time; Pro has no line limit.
How do I cancel?
Open Manage subscription with your key: Stripe's billing portal lets you cancel or change your card. Lifetime keys never renew.