PEG Ratio Calculator
The formula
What the peg ratio tells you
The P/E with growth held accountable — one point of multiple demanded per point of growth, popularized by Peter Lynch as the sanity check on growth stocks.
Calculation: PEG = P/E ÷ expected growth rate. Enter your inputs and every substitution is shown below the result.
Reading the result
PEG near 1 is the fairness line; sub-1 is the classic buy screen. But the growth number is a forecast, so the ratio inherits every optimism in it.
Rules of thumb: <1 cheap; 1–1.5 fair; 2+ expensive on growth-adjusted terms
Limitations and best practice
Single-year growth spikes make anything look cheap — analysts use 3–5-year forward growth for a reason, and sell-side estimates trend wish-fulfillment.
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 PEG handle dividends?
Where does PEG break down?
Source & methodology
Peter Lynch, One Up on Wall Street; standard growth-adjusted screening.
PEG Ratio: what this tool answers
This page was written for one job: turning your own inputs into a defensible figure, with the working shown. PEG Ratio 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 PEG ratio in real time, and see every substitution printed below.
In plain terms, PEG Ratio answers the question "PEG ratio?". 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, Financial Analysis is the context where this figure is quoted most often, and professionals treat it as a first-pass screen rather than a verdict.
Like most useful measures, PEG Ratio is a summary, and summaries hide as much as they reveal. The companion outputs and the input table are here to reopen what the headline compressed.
What makes a calculation page trustworthy is that its copy is derived from its own arithmetic: here PEG ratio = 1.20 ×, recomputed every time a field changes, and the sensitivity section ranks the inputs that move the result — Expected earnings growth first, at ≈11.1 % 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.
Every input in PEG Ratio, and what it does to the answer
One formula, published in full: PEG = P/E ÷ expected growth rate. 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.
P/E ratio (example value 24) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. This input feeds the formula directly; a defensible figure here is worth more than false precision anywhere else.
Expected earnings growth (%) (example value 20) is a quantity rather than a category — precision here is cheap and worth having. Enter it exactly as your document states it — quoted annual, monthly and effective rates are three different numbers.
PEG Ratio with real numbers, step by step
Rather than describe the calculation, here it is end to end — every substitution in order, starting from the inputs above. Starting figures: P/E ratio, Expected earnings growth (%). The computed PEG ratio comes out at 1.20 ×, which the interpretation band labels “Fairly priced for its growth rate”.
- PEG = 24.0 ÷ 20% = 1.20
- A P/E of 24 is only defensible if 24% growth is real and lasting
Growth-adjusted P/E at parity (PEG=1) — 20.0 ×. Compare it against the main result of 1.20 × before drawing conclusions.
Premium factor over parity — 1.20 ×. Compare it against the main result of 1.20 × before drawing conclusions.
Break-even growth for today’s P/E — 24.0 %. Compare it against the main result of 1.20 × before drawing conclusions.
Keep this worked example open while you enter your own figures: matching the shape of the substitution is the fastest way to spot a unit or convention mistake.
Scenario table: PEG Ratio at ±10 % and ±20 % of the key input
The honest version of any estimate is a corridor, and this one is cheap to produce: PEG Ratio was recomputed at 5 points along the dominant input, with every other field left untouched.
| Expected earnings growth setting | PEG ratio |
|---|---|
| 80 % of the example value | 1.50 × |
| 90 % of the example value | 1.33 × |
| example inputs | 1.20 × |
| 110 % of the example value | 1.09 × |
| 120 % of the example value | 1.00 × |
Across 5 settings of Expected earnings growth, the result spans 1.00 × to 1.50 ×. 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 Expected earnings growth alone; the substitution steps will follow your figures exactly.
The levers behind PEG Ratio, ranked by effect
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 PEG ratio was recalculated from scratch. It is the fastest honest answer to “what matters most in PEG Ratio?” — and it is specific to these defaults, because sensitivity moves with the starting point.
- Expected earnings growth: ten percent up gives 1.09 ×, ten percent down gives 1.33 × — ≈11.1 % of the PEG ratio either way
- P/E ratio +10 % → PEG Ratio = 1.32 × · −10 % → 1.08 × (the PEG ratio shifts ≈10.0 %)
Expected earnings growth is the dominant lever here: ten percent either way moves the result by about 11.1 %, from 1.09 × to 1.33 ×. Measure that input from a document rather than from memory, and treat P/E ratio as the second priority (≈10.0 % 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.
Is your PEG Ratio good — reading the result bands
The value above only becomes useful the moment you know what it is being measured against. On the example inputs the band reads “Fairly priced for its growth rate”; your own figures place you on a different rung of the same ladder. How much of that band is luck? On Expected earnings growth alone ten percent either way covers 1.09 × to 1.33 ×. 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.
The comparison worth making is not with somebody else’s PEG Ratio but with the version of your own situation measured last quarter — same formula, same conventions, different inputs.
How people get PEG Ratio wrong
Single-year growth spikes make anything look cheap — analysts use 3–5-year forward growth for a reason, and sell-side estimates trend wish-fulfillment. 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.
Reading PEG Ratio as a promise rather than a conditional. Every number here is of the form “if these inputs, then this result”; when an input moves, the honest response is to recompute rather than to defend the old figure.
This model has its own particular trap: Expected earnings growth carries ≈11.1 % of the response per ten percent of error, so effort spent elsewhere is largely decorative.
A final trap is presentation: reporting PEG Ratio 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.
Before you trust your PEG Ratio: 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.
- Check Expected earnings growth before anything else: it is the measured dominant input, ≈11.1 % of PEG Ratio per ten percent.
- 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.
- Confirm the answer against one independent method or published benchmark for PEG Ratio.
Step by step: getting a trustworthy PEG Ratio 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 PEG Ratio takes a minute to learn and applies to every input above.
Step 1 — start from evidence. The inputs behind PEG Ratio are p/e ratio, expected earnings growth (%). Write them down with their source next to each one; if you cannot name where a figure came from, that is the input most likely to be wrong. A calculation you cannot explain to somebody else is a calculation you cannot defend.
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. Most surprises in numbers are surprises about inputs, not about formulas.
Step 3 — isolate your variables. Change one field, observe, revert. The live sensitivity list does the ranking for the default inputs; verify it against your own, because dominance shifts when the starting point shifts. Half of a good calculation is knowing which input you would hate to be wrong about.
Step 4 — compute a corridor, not a point. Three runs — worst, likely, best — turn PEG Ratio from a snapshot into a range. Plan against the pessimistic end and treat the optimistic end as the upside story. A figure with a date beside it becomes evidence; without one it stays an anecdote.
Step 5 — record the context, not just the number. Note today’s date and the inputs alongside the 1.20 × output. Six months from now the context is what turns this figure into a trend. The inputs are the part of the work that nobody else can do for you.
From calculation to decision: where PEG Ratio earns its keep
Most Financial Analysis disagreements are arithmetic disagreements in disguise. When PEG ratio of 1.20 × 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. Compare the calculation to the rough guess you arrived with, and ask why they differ.
The companion outputs — Growth-adjusted P/E at parity (PEG=1) and Premium factor over parity — 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. Comparisons are cheap: run the identical calculation for the alternative and look at the gap.
There is a personal-administration use people overlook: periodic self-checking. PEG Ratio quietly drifts as life changes — rates move, bodies change, costs compound — and re-running it a few times a year catches drift while correction is still cheap. A calculation you cannot explain to somebody else is a calculation you cannot defend.
PEG Ratio — frequently asked questions
What affects PEG Ratio the most?
PEG Ratio is driven above all by Expected earnings growth. Perturbing only that field by ten percent either way produced 1.09 × against the 1.20 × baseline — a ≈11.1 % response, while P/E ratio manages ≈10.0 %.
Which matters more: p/e ratio or expected earnings growth?
Expected earnings growth, by a factor of about 1.1. Concretely: ten percent on Expected earnings growth is worth ≈11.1 % of PEG Ratio, the same nudge on P/E ratio only ≈10.0 %. That ranking is re-computed for each page from that page’s own defaults.
What is a typical PEG Ratio?
On the worked example above PEG Ratio comes out at 1.20 ×. Treat that as one point on a distribution rather than a norm: the bands, the companion outputs and the sensitivity ranking tell you how wide the plausible range really is.
How do I calculate PEG Ratio by hand?
PEG = P/E ÷ expected growth rate is the entire method. Work the inputs in that order — PEG = 24.0 ÷ 20% = 1.20 — and you will reach 1.20 × on the default figures, the same number this tool prints.
What happens to PEG Ratio if expected earnings growth changes by 10 %?
The engine was re-run with that field moved by ten percent while everything else stayed fixed: the PEG ratio goes across 1.09 × to 1.33 ×, a swing of roughly 11.1 % around the 1.20 × baseline. That ratio is the practical definition of how much this input matters.
Is the PEG Ratio result of 1.20 × good or bad?
Neither, on its own — the label “Fairly priced for its growth rate” 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 Expected earnings growth alone moves it by ≈11.1 %.
What affects PEG Ratio the most?
Sensitivity depends on where you start, but the inputs P/E ratio and Expected earnings growth (%) typically move PEG Ratio further than the rest because they enter the formula multiplicatively. If you can only measure two things well, measure those and hold the others at conservative defaults.
Should I use PEG Ratio before launching?
Yes — a PEG Ratio run on honest inputs before spending is the cheapest consulting an entrepreneur can buy. Re-run at every pricing change; the number moves more often than founders expect.
Does PEG handle dividends?
Not natively — a high-dividend slow grower looks expensive; some add dividend yield to the growth denominator for total-return PEG.
Where does PEG break down?
Negative growth, hypergrowth off small bases, and any company whose growth will mean-revert within the multiple’s horizon.
Does this PEG Ratio 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.
Key terms on this page
- Growth-adjusted P/E at parity (PEG=1)
- 20.0 × on the example inputs — a companion figure printed beside the headline of PEG Ratio so that no result is read in isolation.
- Premium factor over parity
- 1.20 × in the default PEG Ratio calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Break-even growth for today’s P/E
- 24.0 % for the PEG Ratio worked case; it sits next to the main result because it carries context the headline leaves out.
- PEG ratio
- The primary output of this tool: 1.20 × for the default inputs, computed exactly from PEG = P/E ÷ expected growth rate.
- Worked example
- Every substitution in order, from the example inputs to 1.20 × — the audit trail for the headline figure.
- Verdict band
- The interpretation attached to a result (“Fairly priced for its growth rate” on these inputs), which turns a bare number into a position on a scale.
- Sensitivity (±10 %)
- How far the PEG Ratio 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 PEG Ratio model comes from
There is no black box on this page — the engine evaluates PEG = P/E ÷ expected growth rate. Source of record: Peter Lynch, One Up on Wall Street; standard growth-adjusted screening. 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.
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 PEG Ratio 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.