Rule of 40 Calculator
The formula
What the rule of 40 tells you
The software industry's favorite trade-off test: growth plus margin should clear 40 — the market pays for either, but demands at least one.
Calculation: Rule of 40 score = growth % + profit margin %. Enter your inputs and every substitution is shown below the result.
Reading the result
The last line is the strategic content: it prices exactly how much growth you must give up to fund profitability, or vice versa.
Rules of thumb: Public SaaS above 40 trade at meaningful premiums; sub-20 companies compress hard
Limitations and best practice
Definitional drift: EBITDA vs FCF margins differ by capex and SBC; compare within one definition and one season.
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
Does it apply to all software?
What if we are at 15?
Source & methodology
Emergence Capital / OpenView origin; SaaS public-market convention.
Rule of 40: what this tool answers
You are here because you need a specific number, and you want to see how it was produced before you rely on it. Searchers land on a Rule of 40 page for three reasons — to plan, to compare options, and to check that somebody else’s arithmetic is honest. This tool serves all three, and everything after the calculator explains the model instead of hiding it.
A calculation like this one is worth roughly as much as a careful sentence: it forces several vague considerations into one comparable quantity. Once Rule of 40 is on the table, the argument can stop being about impressions.
In plain terms, Rule of 40 answers the question "Rule of 40 score?". The measurement matters because it converts a situation that feels complicated — several inputs pulling in different directions — into a single number you can act on. Within Business & Entrepreneurship, Startup Metrics is the context where this figure is quoted most often, and professionals treat it as a first-pass screen rather than a verdict.
Every figure in the prose is generated by the engine rather than written beside it — the worked example resolves to rule of 40 score = 92.0 on the default inputs, and the sensitivity section ranks the inputs that move the result — Year-over-year revenue growth first, at ≈10.9 % of the headline for a ten-percent error either way in that input. Read the sections in order and you will be able to reproduce every figure by hand.
Inside the Rule of 40 calculation: formula and every input
One formula, published in full: Rule of 40 score = growth % + profit margin %. Anything you can read, you can reproduce in a spreadsheet, and that reproducibility is the whole point of printing it rather than hiding it behind a button.
Year-over-year revenue growth (%) (example value 100) is a measured number in the unit named by the label; the formula does not convert for you. Rates are the most mis-transcribed input on any page like this; copy it from the document rather than retyping from memory.
EBITDA (or FCF) margin (%) (example value -8) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. Check the convention first: if the source says “6.5 % per year”, type 6.5 and let the formula do the rest.
Rule of 40 with real numbers, step by step
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: Year-over-year revenue growth (%), EBITDA (or FCF) margin (%). The endpoint of that chain is 92.0 of rule of 40 score, sitting in the “Elite growth-plus-profit profile” band.
- Score = 100% growth + (-8% margin) = 92.0
Growth contribution — 100.0 %. This is the number experienced users quote when the headline alone would mislead.
Profit contribution — -8.0 %. If your inputs change, this is usually the first companion figure to move.
Max growth acceptable at 40 score — 48.0 %. Compare it against the main result of 92.0 before drawing conclusions.
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.
The Rule of 40 corridor: your result across a realistic band
The honest version of any estimate is a corridor, and this one is cheap to produce: Rule of 40 was recomputed at 5 points along the dominant input, with every other field left untouched.
| Year-over-year revenue growth setting | Rule of 40 score |
|---|---|
| 80 % of the example value | 72.0 |
| 90 % of the example value | 82.0 |
| example inputs | 92.0 |
| 110 % of the example value | 102.0 |
| 120 % of the example value | 112.0 |
Across 5 settings of Year-over-year revenue growth, the result spans 72.0 to 112.0. 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 Year-over-year revenue growth alone; the substitution steps will follow your figures exactly.
Sensitivity: which inputs change Rule of 40 the most
This list was computed for this specific engine just now: each numeric input was nudged ±10 % while every other field held its example value, and the rule of 40 score was recalculated from scratch. For Rule of 40 the ranking is measured rather than guessed, and it belongs to these defaults: shift the starting point and the order can shift with it.
- Nudge Year-over-year revenue growth by ±10 % and Rule of 40 lands between 82.0 and 102.0 (sensitivity ≈10.9 %)
- EBITDA (or FCF) margin: ten percent up gives 91.2, ten percent down gives 92.8 — ≈0.9 % of the rule of 40 score either way
Year-over-year revenue growth is the dominant lever here: ten percent either way moves the result by about 10.9 %, from 82.0 to 102.0. Measure that input from a document rather than from memory, and treat EBITDA (or FCF) margin as the second priority (≈0.9 % 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 Rule of 40 verdict
Nobody acts on a bare figure — they act on a figure with a comparison attached. On the example inputs the band reads “Elite growth-plus-profit profile”; your own figures place you on a different rung of the same ladder. Before treating the band as fact, note its width: ten percent either way on Year-over-year revenue growth already spans 82.0 to 102.0. 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.
Where Rule of 40 sits next to similar measures: this tool answers “how much is the Rule of 40”, while the related calculators answer “what do I do about it”. Reading the result alone tends to over-weight a single snapshot; pairing it with the companion tools above turns the number into a decision.
Common mistakes with Rule of 40 (and the fix)
Definitional drift: EBITDA vs FCF margins differ by capex and SBC; compare within one definition and one season. 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.
Using stale inputs. Rule of 40 is only as current as the numbers behind it — an estimate carried over from a previous season, rate table or report quietly biases every output. Re-measure the inputs first; that single habit fixes more bad Rule of 40 figures than any formula change.
One mistake is specific to this engine: assuming every input matters equally. The computation above shows Year-over-year revenue growth dominating — a careful figure there beats false precision everywhere else.
Another is comparing across contexts: a Rule of 40 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 Rule of 40: a short checklist
- Compare the result with one independent method or published benchmark.
- Verify each input against its original source document, not memory.
- Re-verify Year-over-year revenue growth against a source document — ten percent of error there moves the headline by ≈10.9 %.
- Note the date and the inputs beside the number so the figure can be audited later.
- Confirm the example values are plausible for your own situation before replacing them.
- 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 Rule of 40 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 Rule of 40 takes a minute to learn and applies to every input above.
Step 1 — collect, then type. Everything this tool asks for is listed above (year-over-year revenue growth (%), ebitda (or fcf) margin (%)). 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. Most surprises in numbers are surprises about inputs, not about formulas.
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 Rule of 40 score (92.0 for the example values), and note the verdict band. When two sources disagree, it is almost never the arithmetic that differs.
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. If a result feels obviously right, that is the moment to check the inputs hardest.
Step 4 — compute a corridor, not a point. Three runs — worst, likely, best — turn Rule of 40 from a snapshot into a range. Plan against the pessimistic end and treat the optimistic end as the upside story. When two sources disagree, it is almost never the arithmetic that differs.
Step 5 — schedule the next run. In Business & Entrepreneurship the inputs drift quietly. Put a reminder a quarter out, re-enter the same fields, and read the change rather than the level. If a result feels obviously right, that is the moment to check the inputs hardest.
From calculation to decision: where Rule of 40 earns its keep
Numbers earn their keep in conversations, and Rule of 40 is no exception. In Business & Entrepreneurship discussions around Startup Metrics, 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. The test of a good estimate is not that it feels right but that it changes what you do.
The audience for this page is people who need one trustworthy number before their next decision. In professional Startup Metrics practice the pattern is always the same — screen with Rule of 40, then invest slow analysis only in whatever survives the screen. One decimal place more than your data supports is one decimal place of fiction.
Treat Rule of 40 like a smoke alarm rather than a painting — its value is in being tested periodically, not in being admired once. Say the answer out loud before you save it; if it sounds wrong, the model did not change, your understanding did.
People also ask about Rule of 40
What affects Rule of 40 the most?
The short answer: Year-over-year revenue growth. The longer answer is the sensitivity table on this page, where every numeric input was probed by ten percent and the rule of 40 score recalculated — Year-over-year revenue growth moved it furthest, by roughly 10.9 % (82.0 to 102.0).
Which matters more: ebitda (or fcf) margin or year-over-year revenue growth?
By the numbers, Year-over-year revenue growth: a ten-percent change in it moves the result ≈10.9 %, versus ≈0.9 % for EBITDA (or FCF) margin. Spend your measuring effort in that order — precision on the weaker lever buys almost nothing.
What is a typical Rule of 40?
With the example inputs on this page the result is 92.0, labelled “Elite growth-plus-profit profile”. “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 Rule of 40 by hand?
Rule of 40 score = growth % + profit margin % is the entire method. Work the inputs in that order — Score = 100% growth + (-8% margin) = 92.0 — and you will reach 92.0 on the default figures, the same number this tool prints.
What happens to Rule of 40 if year-over-year revenue growth changes by 10 %?
On these inputs a ±10 % change in year-over-year revenue growth takes Rule of 40 to 102.0 against the 92.0 example — around 10.9 % of the headline. The same test on every other field is in the sensitivity section.
Is the Rule of 40 result of 92.0 good or bad?
The tool answers “what”, not “whether”: 92.0 carries the verdict “Elite growth-plus-profit profile” for the default case, which is a starting interpretation rather than a verdict on your situation. Re-run with your own figures and compare the bands.
What does 92.0 tell me about the business?
It answers the narrow question mechanically and the broad question only in context: Rule of 40 is one dashboard light, and it pairs with unit economics and cash timing before any bet the business size.
How do I calculate Rule of 40 manually?
Write down the inputs, then follow the printed steps in order — Rule of 40 score = growth % + profit margin %. A spreadsheet replicates it with two or three cells. The manual route is worth doing once to build intuition; after that the calculator saves time and eliminates transcription slips.
Does it apply to all software?
Primarily SaaS with subscription revenue; transactional and usage-based models need adapted margins.
What if we are at 15?
Common in early growth stage — the rule becomes binding as an IPO and public-market filter.
Does this Rule of 40 tool store my numbers?
No. The entire calculation runs in your browser session; nothing entered above is transmitted or saved, which is the correct behaviour for sensitive Business & Entrepreneurship figures and the reason you can re-run this page as often as you like.
What the labels on this page mean
- Growth contribution
- 100.0 % for the Rule of 40 worked case; it sits next to the main result because it carries context the headline leaves out.
- Profit contribution
- -8.0 % in the default Rule of 40 calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Max growth acceptable at 40 score
- 48.0 % in the default Rule of 40 calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Rule of 40 score
- The primary output of this tool: 92.0 for the default inputs, computed exactly from Rule of 40 score = growth % + profit margin %.
- Worked example
- The calculation written out in full so that nothing on this page has to be taken on trust.
- Verdict band
- A named zone on the range of plausible results; the example inputs land in “Elite growth-plus-profit profile”, and your inputs may not.
- Sensitivity (±10 %)
- How far the Rule of 40 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 Rule of 40 model comes from
There is no black box on this page — the engine evaluates Rule of 40 score = growth % + profit margin %. Source of record: Emergence Capital / OpenView origin; SaaS public-market convention. 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.
This page is an estimation aid, not professional advice. The design rule is simple: two people entering identical figures must get identical answers. 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.
Turning this Rule of 40 into a decision
Re-run the calculation with your own figures, stress the two most sensitive inputs by ±10 %, and only then act on the result.
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.