Insider Ownership Calculator
The formula
What the insider ownership tells you
Tape-meat body composition for insider ownership: the US Navy circumference method — the field standard gyms and physicals actually use — with fat and lean mass in kilograms.
Calculation: US Navy: BF% = 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76 (men); +1.08·…−84.52 women. Enter your inputs and every substitution is shown below the result.
Reading the result
Track the trend monthly under the same conditions; ±2 points of tape error is normal.
Limitations and best practice
Hydration and recent meals shift centimetres — measure fasted, morning, same spot.
This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Frequently asked questions
How accurate is tape-meat body fat?
Which formula is best for me?
Source & methodology
US Navy Body Composition Program method.
Insider Ownership explained: formula, worked example and honest limits
You are here because you need a specific number, and you want to see how it was produced before you rely on it. There are plenty of pages about Insider Ownership; almost none of them show the working. This one does: the formula, every input, a fully computed example, and a sensitivity analysis calculated live from this engine’s own defaults.
People rarely disagree about arithmetic; they disagree about assumptions that were never written down. Printing the substitution and the sensitivity ranking removes that category of disagreement for Insider Ownership.
What makes Insider Ownership worth calculating is not precision but position: it tells you which side of a threshold you are on, and by how much. A rough figure that settles the direction beats an elaborate one that never commits.
What makes a calculation page trustworthy is that its copy is derived from its own arithmetic: here body fat = 27.3%, recomputed every time a field changes, and the sensitivity section ranks the inputs that move the result — Waist / hip circumference first, at ≈25.6 % of the headline for a ten-percent error either way in that input — which is the thread the rest of this guide pulls on.
The Insider Ownership formula, explained
The engine implements a single stated model: US Navy: BF% = 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76 (men); +1.08·…−84.52 women. There is no hidden coefficient and no login-gated precision — the formula printed is the formula executed, which is also what makes the result citable.
Weight (kg) (example value 63) is a measured number in the unit named by the label; the formula does not convert for you. Weigh rather than estimate where you can — this field usually enters the formula multiplicatively.
Height (cm) (example value 183) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. Small measurement errors grow here: a length that is squared or cubed in the model magnifies a one-percent slip into a three-percent answer.
Neck / waist circumference (cm) (example value 38) is a quantity rather than a category — precision here is cheap and worth having. This input feeds the formula directly; a defensible figure here is worth more than false precision anywhere else.
Waist / hip circumference (cm) (example value 92) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. The example value is there to demonstrate the mechanics, not to describe your situation — overwrite it.
Sex (example value Male) is a categorical input — the option you choose decides which numbers the formula uses. If you are unsure what belongs in this field, look at the printed steps: the substitution shows exactly how the engine uses it.
What each “Sex” choice actually does: Male → 27.3% · Female → 2.0% That table is the honest answer to “does this option matter”, re-derived from the formula rather than hard-coded into page copy.
The default Insider Ownership calculation, written out in full
Rather than describe the calculation, here it is end to end — every substitution in order, starting from the inputs above. Starting figures: Weight (kg), Height (cm), Neck / waist circumference (cm), Waist / hip circumference (cm). Run to the end, the body fat resolves to 27.3% — Above the healthy band — the trend matters more than today’s point on the bands this tool uses.
- Circumference difference waist−neck = 54.0 cm
- Navy formula (log₁₀ terms) → 27.3 %
- Fat mass = 63.0 × 27.3 % = 17.2 kg
Fat mass — 17.2 kg. Read next to the headline, this is the figure that shows the shape of the trade-off.
Lean mass — 45.8 kg. Read next to the headline, this is the figure that shows the shape of the trade-off.
BMI — 18.8. Read next to the headline, this is the figure that shows the shape of the trade-off.
Re-running with your own figures is instant; re-running by hand once is the best way to know the tool is telling you the truth.
How far Insider Ownership can reasonably move
Read this table as the practical error bar on the headline figure. It answers the question people actually have after seeing a single number: how wrong could this be if the main input is off by ten or twenty percent?
| Waist / hip circumference setting | Body fat |
|---|---|
| 80 % of the example value | 11.7% |
| 90 % of the example value | 20.3% |
| example inputs | 27.3% |
| 110 % of the example value | 33.2% |
| 120 % of the example value | 38.3% |
Across 5 settings of Waist / hip circumference, the result spans 11.7% to 38.3%. A decision that only works at one row of this table is a decision waiting for an input to move. Reproduce it in the form above by editing Waist / hip circumference alone; the substitution steps will follow your figures exactly.
Sensitivity: which inputs change Insider Ownership the most
Generic advice says “it depends on your inputs”; this section says exactly how much. Each field was perturbed by ±10 % in isolation and the body fat recomputed, so the ranking below is measured rather than asserted. Read it as a map of where Insider Ownership is fragile — drawn for the example inputs, which is the map you want when deciding what to measure carefully.
- Nudge Waist / hip circumference by ±10 % and Insider Ownership lands between 20.3% and 33.2% (sensitivity ≈25.6 %)
- Height: ten percent up gives 24.4%, ten percent down gives 30.5% — ≈11.7 % of the body fat either way
- Nudge Neck / waist circumference by ±10 % and Insider Ownership lands between 24.6% and 29.8% (sensitivity ≈10.0 %)
Waist / hip circumference is the dominant lever here: ten percent either way moves the result by about 25.6 %, from 20.3% to 33.2%. Measure that input from a document rather than from memory, and treat Height as the second priority (≈11.7 % per ten percent). Everything below that can stay approximate, which is a licence to stop chasing data that would not change the decision.
Reading the result: bands, zones and thresholds
The value above only becomes useful the moment you know what it is being measured against. The verdict attached to the default calculation — “Above the healthy band — the trend matters more than today’s point” — is one band on a ladder your own figure may sit somewhere else on. Before treating the band as fact, note its width: ten percent either way on Waist / hip circumference already spans 20.3% to 33.2%. The practical reading rules: ask what would have to change to move you one band. If the answer is “a small, plausible input difference”, the band itself is not the finding — the uncertainty is.
Compared with charting sites, this page explains the formula rather than hiding it — the goal is a number you can defend in a meeting, not just display.
How people get Insider Ownership wrong
Hydration and recent meals shift centimetres — measure fasted, morning, same spot. This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Chasing one metric. Insider Ownership needs its pair (Fat mass) the way a speedometer needs fuel pressure — one number alone has burned more portfolios than bad markets.
One mistake is specific to this engine: assuming every input matters equally. The computation above shows Waist / hip circumference dominating — a careful figure there beats false precision everywhere else.
Another is comparing across contexts: an Insider Ownership computed with one set of conventions should never be lined up against a figure computed with another. Check the inputs behind both before ranking them.
Before you trust your Insider Ownership: a short checklist
- Compare the result with one independent method or published benchmark.
- Check that every field the formula needs actually arrived from a document, not from recollection.
- Put Waist / hip circumference under a magnifier; the sensitivity table above is the reason why.
- Verify each input against its original source document, not memory.
- Note the date and the inputs beside the number so the figure can be audited later.
- Repeat the ±10 % test on the inputs that matter and see whether the decision — not just the number — still holds.
Step by step: getting a trustworthy Insider Ownership out of this tool
The tool does the arithmetic; the routine below is what makes the arithmetic trustworthy. Five steps, a minute total — and afterwards you will know not just what the number is, but which assumption produced it.
Step 1 — collect, then type. Everything this tool asks for is listed above (weight (kg), height (cm), neck / waist circumference (cm), waist / hip circumference (cm), sex). Pull each figure from something you can point at — paperwork, a dashboard, a label — before touching a field. Guesswork at the input stage cannot be repaired at the interpretation stage. If the verdict changes with a ten-percent nudge, report the nudge alongside the number.
Step 2 — start from the case you can defend. Enter pessimistic-but-honest figures first; the optimistic run is a ceiling, not a plan. A conclusion that holds on conservative inputs holds everywhere. Half of a good calculation is knowing which input you would hate to be wrong about.
Step 3 — play with the inputs on purpose. Ten percent up, ten percent down, one field at a time. Within a few minutes you will know this calculation better than most people who quote its results. Compare the calculation to the rough guess you arrived with, and ask why they differ.
Step 4 — run the scenario trio. Expected, pessimistic, optimistic. The gap between pessimistic and expected is the number to plan against; the optimistic result is useful only as a ceiling. Precision is a promise you make about your data; make sure your inputs can keep it.
Step 5 — schedule the next run. In Investing & Markets the inputs drift quietly. Put a reminder a quarter out, re-enter the same fields, and read the change rather than the level. Write the figure down before moving on; memory flatters whichever number you saw last.
From calculation to decision: where Insider Ownership earns its keep
Numbers earn their keep in conversations, and Insider Ownership is no exception. In Investing & Markets discussions around Stocks & Equities, this figure decides whether an option stays on the table: it converts an opinionated debate into an arithmetic one, and arithmetic is the only referee both sides accept. When two sources disagree, it is almost never the arithmetic that differs.
The audience for this page is people who need one trustworthy number before their next decision. In professional Stocks & Equities practice the pattern is always the same — screen with Insider Ownership, then invest slow analysis only in whatever survives the screen. A figure nobody can reproduce is a figure nobody will act on twice.
Treat Insider Ownership like a smoke alarm rather than a painting — its value is in being tested periodically, not in being admired once. If the verdict changes with a ten-percent nudge, report the nudge alongside the number.
People also ask about Insider Ownership
What affects Insider Ownership the most?
Insider Ownership is driven above all by Waist / hip circumference. Perturbing only that field by ten percent either way produced 33.2% against the 27.3% baseline — a ≈25.6 % response, while Height manages ≈11.7 %.
Which matters more: height or waist / hip circumference?
By the numbers, Waist / hip circumference: a ten-percent change in it moves the result ≈25.6 %, versus ≈11.7 % for Height. Spend your measuring effort in that order — precision on the weaker lever buys almost nothing.
How much does the “Sex” choice change the answer?
Across every option this tool offers, the body fat ranges from 2.0% (Female) to 27.3% (Male) with all other inputs held at their example values. The per-option table is printed in the inputs section — this is a decision that genuinely moves the number, not a cosmetic dropdown.
What is a typical Insider Ownership?
With the example inputs on this page the result is 27.3%, labelled “Above the healthy band — the trend matters more than today’s point”. “Typical” varies with situation, which is why every result here ships with its verdict band and its sensitivity list: they turn one figure into a range you can locate yourself inside.
How do I calculate Insider Ownership by hand?
Use the stated model — US Navy: BF% = 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76 (men); +1.08·…−84.52 women — and substitute in the order the tool prints (it starts from Circumference difference waist−neck = 54.0 cm). On the example inputs the hand route lands on 27.3%, exactly what the calculator shows. A spreadsheet reproduces it in two or three cells; doing it once by hand is what makes the automated answer trustworthy.
What happens to Insider Ownership if waist / hip circumference changes by 10 %?
On these inputs a ±10 % change in waist / hip circumference takes Insider Ownership to 33.2% against the 27.3% example — around 25.6 % of the headline. The same test on every other field is in the sensitivity section.
Is the Insider Ownership result of 27.3% good or bad?
Good and bad are comparisons, so the honest test is three questions: where does your own Insider Ownership sit against the 27.3% reference above, how far would a plausible input error move it (≈25.6 % per ten percent on Waist / hip circumference), and what does the alternative option compute to?
How often should I check Insider Ownership?
Whenever an input changes by more than a few percent, and otherwise on the rhythm of your decisions — before a purchase, a review, a renewal. Insider Ownership is a snapshot, not a subscription; stale snapshots are the most common silent error in Investing & Markets planning.
What is a good Insider Ownership?
Markets give away free benchmarks: anything that beats the relevant index after costs earns the label "good", and this tool’s verdict band translates Insider Ownership against experience ranges. Before that, check that the inputs are realistic — a great Insider Ownership built on optimistic inputs is just a nicer-looking error.
How accurate is tape-meat body fat?
±3 points versus DEXA in lean subjects, better in groups; the trend is reliable even when the level is soft.
Which formula is best for me?
Consistency beats formula choice — the same method, same conditions, every time.
Can this tool see the numbers I type?
It cannot. There is no submission step: the calculation happens in your browser and the result disappears when you close the page. Treat the fields above as a scratchpad rather than a form.
What the labels on this page mean
- Fat mass
- 17.2 kg on the example inputs — a companion figure printed beside the headline of Insider Ownership so that no result is read in isolation.
- Lean mass
- 45.8 kg for the Insider Ownership worked case; it sits next to the main result because it carries context the headline leaves out.
- BMI
- 18.8 for the Insider Ownership worked case; it sits next to the main result because it carries context the headline leaves out.
- Body fat
- The primary output of this tool: 27.3% for the default inputs, computed exactly from US Navy: BF% = 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76 (men); +1.08·…−84.52 women.
- Worked example
- Every substitution in order, from the example inputs to 27.3% — the audit trail for the headline figure.
- Verdict band
- The interpretation attached to a result (“Above the healthy band — the trend matters more than today’s point” on these inputs), which turns a bare number into a position on a scale.
- Sensitivity (±10 %)
- How far the Insider Ownership moves when a single input is nudged ten percent either way; the ranked list on this page is computed live from this engine.
Where the Insider Ownership model comes from
Everything above runs on one stated formula, applied without hidden coefficients: US Navy: BF% = 86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76 (men); +1.08·…−84.52 women. Source of record: US Navy Body Composition Program method. Where a professional version of this calculation differs, it differs in inputs and jurisdiction-specific coefficients, not in the algebra — which is why re-checking your inputs beats hunting for a second calculator.
Treat the output as a precise answer to the question you typed: exact arithmetic, transparent formula, published source, no hidden rounding. What that buys you is reproducibility — two people, two browsers, the same arithmetic, and a printed trail from inputs to result that either of them can audit.
Turning this Insider Ownership into a decision
Save the number together with its inputs and today’s date; an Insider Ownership figure without context is unusable the moment an input changes.
This page was written for people who need one trustworthy number before their next decision, and the promise is that nothing above required trust. Bookmark the tool, re-run it whenever an input moves by more than a few percent, and keep the date with the number.