Anti-Dilution (Broad) Calculator
The formula
What the broad-based weighted average tells you
The workhorse anti-dilution formula: prior preferred reprices on a down round, but only in proportion to the new money's size against the whole diluted cap table.
Calculation: CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice). Enter your inputs and every substitution is shown below the result.
Reading the result
A small down round barely moves it — the severity line shows how much of the price gap actually transferred to founders.
Rules of thumb: Broad-based WA is the market-standard Series A+ ask
Limitations and best practice
"Broad-based" must be defined: including options and convertibles in the denominator is what makes it mild. Read the definition, not the label.
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
Broad vs narrow?
Who pays for anti-dilution?
Source & methodology
NVCA model certificate of incorporation.
Anti-Dilution (Broad) 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. Anti-Dilution (Broad) is the kind of number people argue about from memory. This page ends that argument with arithmetic you can watch happen: enter your figures, get Adjusted conversion price in real time, and see every substitution printed below.
It helps to separate the mechanics from the interpretation. The mechanics are fixed: CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice). Anyone, anywhere, entering the same inputs will get the same 18.56 $. The interpretation is where experience counts: whether 18.56 $ is good, normal or alarming depends on comparisons covered below, and that is the part most articles about Anti-Dilution (Broad) never explain.
Business runs on numbers that are cheap to compute and expensive to ignore. Anti-Dilution (Broad) in Business & Entrepreneurship is one of those: CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice), and the gap between founders who check and founders who hope shows up exactly here.
What makes a calculation page trustworthy is that its copy is derived from its own arithmetic: here adjusted conversion price = 18.56 $, recomputed every time a field changes, and the sensitivity section ranks the inputs that move the result — Prior price per share first, at ≈9.7 % of the headline for a ten-percent error either way in that input. Work down the page and by the end you could re-derive the result in a spreadsheet from memory.
How Anti-Dilution (Broad) is computed, line by line
Here is the complete model this tool runs — CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice) — with each input explained below. If a competitor’s page gives you a different answer from the same inputs, this is the text that settles which of you is right.
Prior price per share ($) (example value 19) is a plain measured quantity — the unit shown in the label is the unit the formula expects. If your source quotes a figure before and after some deduction, decide which one the formula wants and be consistent for every field.
New round price ($) (example value 10) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. Keep every money input in the same currency; mixing systems quietly corrupts the comparison.
Broad-based fully diluted shares (example value 12,019,230) is a quantity rather than a category — precision here is cheap and worth having. Replace the example with the figure from your own records — the tool recomputes instantly and the printed steps follow your numbers.
New money ($) (example value 6,246,217) is a measured number in the unit named by the label; the formula does not convert for you. This input feeds the formula directly; a defensible figure here is worth more than false precision anywhere else.
The default Anti-Dilution (Broad) calculation, written out in full
The tool prints its own working; this is the same arithmetic on the example values, reproduced so you can follow it by hand. Starting figures: Prior price per share ($), New round price ($), Broad-based fully diluted shares, New money ($). Run to the end, the adjusted conversion price resolves to 18.56 $ — Prior holders gain 7,877 extra shares (+2.4%) on the bands this tool uses.
- CP₂ = 19 × 12,347,978 ÷ 12,643,852 = $18.56
- Stake expands from 328,748 to 336,625 shares
Shares before adjustment — 328,748. This is the number experienced users quote when the headline alone would mislead.
Shares after adjustment — 336,625. Compare it against the main result of 18.56 $ before drawing conclusions.
Reprice severity — 2.3 %. This is the number experienced users quote when the headline alone would mislead.
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 Anti-Dilution (Broad) 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?
| Prior price per share setting | Adjusted conversion price |
|---|---|
| 80 % of the example value | 14.94 $ |
| 90 % of the example value | 16.75 $ |
| example inputs | 18.56 $ |
| 110 % of the example value | 20.36 $ |
| 120 % of the example value | 22.17 $ |
The corridor runs from 14.94 $ to 22.17 $ across that band — which is the range worth planning inside rather than the single 18.56 $ point estimate. Reproduce it in the form above by editing Prior price per share alone; the substitution steps will follow your figures exactly.
What actually moves your Anti-Dilution (Broad)
Generic advice says “it depends on your inputs”; this section says exactly how much. Each field was perturbed by ±10 % in isolation and the adjusted conversion price recomputed, so the ranking below is measured rather than asserted. Read it as a map of where Anti-Dilution (Broad) is fragile — drawn for the example inputs, which is the map you want when deciding what to measure carefully.
- Prior price per share: ten percent up gives 20.36 $, ten percent down gives 16.75 $ — ≈9.7 % of the adjusted conversion price either way
- New round price +10 % → Anti-Dilution (Broad) = 18.64 $ · −10 % → 18.45 $ (the adjusted conversion price shifts ≈0.5 %)
- Broad-based fully diluted shares +10 % → Anti-Dilution (Broad) = 18.59 $ · −10 % → 18.51 $ (the adjusted conversion price shifts ≈0.3 %)
- New money: ten percent up gives 18.51 $, ten percent down gives 18.60 $ — ≈0.2 % of the adjusted conversion price either way
Prior price per share is the dominant lever here: ten percent either way moves the result by about 9.7 %, from 16.75 $ to 20.36 $. Measure that input from a document rather than from memory, and treat New round price as the second priority (≈0.5 % per ten percent). The remaining fields can sit at safe defaults without materially changing the answer — knowing which is which is what separates a careful calculation from an anxious one.
Interpreting the Anti-Dilution (Broad) verdict
A number on its own is trivia; a number against a range is intelligence. On the example inputs the band reads “Prior holders gain 7,877 extra shares (+2.4%)”; your own figures place you on a different rung of the same ladder. The sensitivity list shows how far a modest input error moves you along that ladder: for Prior price per share, ±10 % covers 16.75 $ to 20.36 $. The practical reading rules: compare against your own history before comparing against other people; treat band boundaries as zones, not walls — one point on the wrong side of a threshold rarely changes a real outcome; and when a companion output contradicts the headline, believe the pair.
The comparison worth making is not with somebody else’s Anti-Dilution (Broad) but with the version of your own situation measured last quarter — same formula, same conventions, different inputs.
Why Anti-Dilution (Broad) results go wrong — and how to prevent it
"Broad-based" must be defined: including options and convertibles in the denominator is what makes it mild. Read the definition, not the label. 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.
Copying a single headline number without checking the companion outputs. The tool reports Shares before adjustment, Shares after adjustment and Reprice severity alongside the main result precisely because Anti-Dilution (Broad) in isolation misleads — the secondary columns are where outliers and trade-offs show up.
This model has its own particular trap: Prior price per share carries ≈9.7 % of the response per ten percent of error, so effort spent elsewhere is largely decorative.
A final trap is presentation: reporting Anti-Dilution (Broad) to more decimal places than the inputs support. The tool prints what the arithmetic gives; you should quote only what your least precise field justifies.
Anti-Dilution (Broad) verification checklist
- Confirm the example values are plausible for your own situation before replacing them.
- Compare the output against one published benchmark or a colleague’s independent estimate.
- Re-verify Prior price per share against a source document — ten percent of error there moves the headline by ≈9.7 %.
- Check that every field the formula needs actually arrived from a document, not from recollection.
- Re-run the calculation with a ±10 % stress on the two most sensitive inputs.
- Confirm the answer against one independent method or published benchmark for Anti-Dilution (Broad).
Step by step: getting a trustworthy Anti-Dilution (Broad) out of this tool
Using a calculator well sounds trivial, but the difference between a decision-grade figure and a throwaway one lives entirely in the routine. The routine for Anti-Dilution (Broad) takes a minute to learn and applies to every input above.
Step 1 — collect, then type. Everything this tool asks for is listed above (prior price per share ($), new round price ($), broad-based fully diluted shares, new money ($)). 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. The point of transparency is that a reader can disagree with a specific line rather than with you.
Step 2 — enter the conservative case first. Resist the flattering scenario. Type the inputs you would defend in front of a sceptical reader, read the Adjusted conversion price (18.56 $ for the example values), and note the verdict band. If the answer changes your behaviour, it deserves a second run with different assumptions.
Step 3 — measure what deserves measuring. The ranked levers above tell you where a careful figure pays off. Everything else can stay approximate, which is a licence to stop hunting for data you do not need. The point of transparency is that a reader can disagree with a specific line rather than with you.
Step 4 — ask what would have to be true. Take the result you want and work backwards through the inputs until you find the assumption that produces it; then decide honestly whether that assumption is defensible. Suspiciously tidy answers deserve the same scrutiny as untidy ones.
Step 5 — write the one-line memo. “Adjusted conversion price = 18.56 $ on this date, from these inputs.” That line is the entire deliverable; everything else on this page is how you earned the right to write it. Suspiciously tidy answers deserve the same scrutiny as untidy ones.
Who actually uses Anti-Dilution (Broad) — and when
Most Startup Metrics disagreements are arithmetic disagreements in disguise. When Adjusted conversion price of 18.56 $ sits on the table with its working shown, the conversation stops being about who sounds more confident and starts being about which input is wrong. Note the assumption you are least sure about; that is where the real risk lives.
The companion outputs — Shares before adjustment and Shares after adjustment — exist for the second stage of that screen: the headline sizes the prize, while the companions describe the trade-off you are accepting to get it. Say the answer out loud before you save it; if it sounds wrong, the model did not change, your understanding did.
Nothing here is stored or transmitted, so the habit of checking is free: open the page, re-enter current figures, compare with the number you saved last time. Estimates improve most when the worst case is written down in ink.
The questions that come up most about Anti-Dilution (Broad)
What affects Anti-Dilution (Broad) the most?
The short answer: Prior price per share. The longer answer is the sensitivity table on this page, where every numeric input was probed by ten percent and the adjusted conversion price recalculated — Prior price per share moved it furthest, by roughly 9.7 % (16.75 $ to 20.36 $).
Which matters more: new round price or prior price per share?
Prior price per share, by a factor of about 17.8. Concretely: ten percent on Prior price per share is worth ≈9.7 % of Anti-Dilution (Broad), the same nudge on New round price only ≈0.5 %. That ranking is re-computed for each page from that page’s own defaults.
What is a typical Anti-Dilution (Broad)?
With the example inputs on this page the result is 18.56 $, labelled “Prior holders gain 7,877 extra shares (+2.4%)”. “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 Anti-Dilution (Broad) by hand?
CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice) is the entire method. Work the inputs in that order — CP₂ = 19 × 12,347,978 ÷ 12,643,852 = $18.56 — and you will reach 18.56 $ on the default figures, the same number this tool prints.
What happens to Anti-Dilution (Broad) if prior price per share changes by 10 %?
On these inputs a ±10 % change in prior price per share takes Anti-Dilution (Broad) to 20.36 $ against the 18.56 $ example — around 9.7 % of the headline. The same test on every other field is in the sensitivity section.
Is the Anti-Dilution (Broad) result of 18.56 $ good or bad?
Neither, on its own — the label “Prior holders gain 7,877 extra shares (+2.4%)” is the band this figure falls in for the example inputs, and your own inputs will place you elsewhere on the same ladder. Judge the number against your history and your alternatives, and remember that a ten-percent error in Prior price per share alone moves it by ≈9.7 %.
Is Anti-Dilution (Broad) accurate?
The arithmetic is exact: CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice) is evaluated with full floating-point precision and every substitution is printed in the worked example. What limits accuracy is input quality and the model’s assumptions, so treat the 18.56 $ result as the correct answer to the question you typed — and check the assumptions section before acting on it.
What does 18.56 $ tell me about the business?
It answers the narrow question mechanically and the broad question only in context: Anti-Dilution (Broad) is one dashboard light, and it pairs with unit economics and cash timing before any bet the business size.
Broad vs narrow?
Narrow-based counts fewer shares and bites harder — the same numbers can differ by points of ownership.
Who pays for anti-dilution?
Common stockholders: the adjustment is a pure transfer from founders and employees to prior preferred.
Do I need an account to use this Anti-Dilution (Broad) calculator?
No, and no data leaves the tab. The engine runs in the page itself, which is why the worked example, the bands and the sensitivity ranking all respond instantly to your keystrokes.
The vocabulary of Anti-Dilution (Broad)
- Shares before adjustment
- 328,748 on the example inputs — a companion figure printed beside the headline of Anti-Dilution (Broad) so that no result is read in isolation.
- Shares after adjustment
- 336,625 for the Anti-Dilution (Broad) worked case; it sits next to the main result because it carries context the headline leaves out.
- Reprice severity
- 2.3 % in the default Anti-Dilution (Broad) calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Adjusted conversion price
- The primary output of this tool: 18.56 $ for the default inputs, computed exactly from CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice).
- Worked example
- The calculation written out in full so that nothing on this page has to be taken on trust.
- Verdict band
- The plain-language label — here “Prior holders gain 7,877 extra shares (+2.4%)” — mapping the computed figure onto experience-based ranges for Business & Entrepreneurship.
- Sensitivity (±10 %)
- How far the Anti-Dilution (Broad) moves when a single input is nudged ten percent either way; the ranked list on this page is computed live from this engine.
Method, sources and what this tool cannot tell you
The model is published arithmetic implemented exactly as written: CP₂ = CP₁ × (Out + NewMoney÷CP₁) ÷ (Out + NewMoney÷newPrice). Source of record: NVCA model certificate of incorporation. Any other implementation of this model should return the same figure for the same inputs. If one does not, the difference is in its assumptions — which this page prints and that one probably does not.
Nothing here replaces a qualified professional, and nothing here is approximate either — the arithmetic is exact, and the honesty is in the inputs you supply. The sensitivity table above is part of that promise rather than a bonus: it lets you see how much of the result depends on how carefully you measured.
After the number: what to do with it
Save the number together with its inputs and today’s date; an Anti-Dilution (Broad) 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.