SAFE Note Conversion Calculator
The formula
What the safe conversion tells you
A SAFE is priced two ways — valuation cap and discount — and converts at whichever favors the holder. This identifies the binding term and the resulting stake.
Calculation: Conversion basis = min(cap, round post × (1 − discount)); ownership = SAFE ÷ basis. Enter your inputs and every substitution is shown below the result.
Reading the result
The tie-point line tells you which term governs your round: most hot caps bind only until rounds run past them, then the discount takes over.
Rules of thumb: Caps typically 40–70% of expected round post; discounts 15–25%
Limitations and best practice
Post-money SAFEs (YC 2018) count the SAFE against the founders' slice directly, and stacked SAFEs dilute geometrically — model the whole class, not one note.
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
What if several SAFEs stack?
Do SAFEs accrue interest?
Source & methodology
Y Combinator post-money SAFE (2018).
SAFE Note Conversion explained: formula, worked example and honest limits
A conversion is trivial until it is wrong, and wrong conversions are invisible unless the factor is printed. There are plenty of pages about SAFE Note Conversion; 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.
What makes SAFE Note Conversion 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.
A calculation like this one is worth roughly as much as a careful sentence: it forces several vague considerations into one comparable quantity. Once SAFE Note Conversion is on the table, the argument can stop being about impressions.
Every figure in the prose is generated by the engine rather than written beside it — the worked example resolves to SAFE stake at conversion = 5.1 % on the default inputs, and the sensitivity section ranks the inputs that move the result — Valuation cap 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.
Inside the SAFE Note Conversion calculation: formula and every input
Here is the complete model this tool runs — Conversion basis = min(cap, round post × (1 − discount)); ownership = SAFE ÷ basis — 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.
SAFE investment ($) (example value 315,000) is a measured number in the unit named by the label; the formula does not convert for you. Replace the example with the figure from your own records — the tool recomputes instantly and the printed steps follow your numbers.
Valuation cap ($) (example value 6,174,258) is a plain measured quantity — the unit shown in the label is the unit the formula expects. If you are unsure what belongs in this field, look at the printed steps: the substitution shows exactly how the engine uses it.
Discount (%) (example value 18) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. Rates are the most mis-transcribed input on any page like this; copy it from the document rather than retyping from memory.
Round post-money ($) (example value 16,997,821) is a plain measured quantity — the unit shown in the label is the unit the formula expects. This input feeds the formula directly; a defensible figure here is worth more than false precision anywhere else.
SAFE Note Conversion on the example inputs: the complete substitution
Rather than describe the calculation, here it is end to end — every substitution in order, starting from the inputs above. Starting figures: SAFE investment ($), Valuation cap ($), Discount (%), Round post-money ($). The computed SAFE stake at conversion comes out at 5.1 %, which the interpretation band labels “The valuation cap binds — the discount is a dead letter”.
- Discounted post = $16,997,821 × (1 − 18%) = $13,938,213; vs cap $6,174,258 → basis $6,174,258
- Ownership = $315,000 ÷ $6,174,258 = 5.1%
Conversion basis (effective post) — $6,174,258. If your inputs change, this is usually the first companion figure to move.
Effective per-$ terms vs round investors — 63.7 %. Read next to the headline, this is the figure that shows the shape of the trade-off.
Round post at which cap and discount tie — $7,529,583. If your inputs change, this is usually the first companion figure to move.
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: SAFE Note Conversion at ±10 % and ±20 % of the key input
The honest version of any estimate is a corridor, and this one is cheap to produce: SAFE Note Conversion was recomputed at 5 points along the dominant input, with every other field left untouched.
| Valuation cap setting | SAFE stake at conversion |
|---|---|
| 80 % of the example value | 6.4 % |
| 90 % of the example value | 5.7 % |
| example inputs | 5.1 % |
| 110 % of the example value | 4.6 % |
| 120 % of the example value | 4.3 % |
The corridor runs from 4.3 % to 6.4 % across that band — which is the range worth planning inside rather than the single 5.1 % point estimate. Reproduce it in the form above by editing Valuation cap alone; the substitution steps will follow your figures exactly.
Where SAFE Note Conversion is fragile — and where it is not
Generic advice says “it depends on your inputs”; this section says exactly how much. Each field was perturbed by ±10 % in isolation and the SAFE stake at conversion recomputed, so the ranking below is measured rather than asserted. For SAFE Note Conversion 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 Valuation cap by ±10 % and SAFE Note Conversion lands between 4.6 % and 5.7 % (sensitivity ≈11.1 %)
- Nudge SAFE investment by ±10 % and SAFE Note Conversion lands between 4.6 % and 5.6 % (sensitivity ≈10.0 %)
Valuation cap is the dominant lever here: ten percent either way moves the result by about 11.1 %, from 4.6 % to 5.7 %. Spend your verification effort there first, and treat SAFE investment 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.
What a SAFE Note Conversion of 5.1 % means in practice
The value above only becomes useful the moment you know what it is being measured against. The verdict attached to the default calculation — “The valuation cap binds — the discount is a dead letter” — is one band on a ladder your own figure may sit somewhere else on. How much of that band is luck? On Valuation cap alone ten percent either way covers 4.6 % to 5.7 %. 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.
Placing this figure in context: calculators of this kind differ less in arithmetic than in what they choose to ignore. This one keeps SAFE investment ($) explicit so that the omissions are visible rather than hidden in a preset.
Common mistakes with SAFE Note Conversion (and the fix)
Post-money SAFEs (YC 2018) count the SAFE against the founders' slice directly, and stacked SAFEs dilute geometrically — model the whole class, not one note. 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.
Leaving a line out of the input. An omitted fee, tax or headcount is not a rounding error — it is a structural optimism bias.
Attention is also misallocated between fields. Having measured this engine, we can say where it belongs: Valuation cap first, everything else second.
A final trap is presentation: reporting SAFE Note Conversion 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.
A quick check for any SAFE Note Conversion figure
- Verify each input against its original source document, not memory.
- Re-run the calculation with a ±10 % stress on the two most sensitive inputs.
- Check Valuation cap before anything else: it is the measured dominant input, ≈11.1 % of SAFE Note Conversion per ten percent.
- Record the date and the inputs alongside the number so future-you knows what was assumed.
- Recompute once with the dominant input deliberately set low, and see whether the decision changes.
- Run the ±10 % stress on the top two levers and check that your conclusion survives both.
Step by step: getting a trustworthy SAFE Note Conversion 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 SAFE Note Conversion takes a minute to learn and applies to every input above.
Step 1 — one document, one pass. Open the statement, label or record that holds safe investment ($), valuation cap ($), discount (%), round post-money ($) and transcribe straight into the form. Transcription from a single source removes the mismatch errors that appear when figures are assembled from three different places. Repeating a calculation with the same numbers proves only that the arithmetic is reliable — which is worth knowing.
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. The inputs are the part of the work that nobody else can do for you.
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. One decimal place more than your data supports is one decimal place of fiction.
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. The inputs are the part of the work that nobody else can do for you.
Step 5 — record the context, not just the number. Note today’s date and the inputs alongside the 5.1 % output. Six months from now the context is what turns this figure into a trend. Write the assumptions in the same file as the result, and future arguments take minutes instead of meetings.
Where SAFE Note Conversion matters in practice
Numbers earn their keep in conversations, and SAFE Note Conversion 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 anyone translating a figure between units or systems. In professional Startup Metrics practice the pattern is always the same — screen with SAFE Note Conversion, then invest slow analysis only in whatever survives the screen. A figure nobody can reproduce is a figure nobody will act on twice.
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. When two sources disagree, it is almost never the arithmetic that differs.
People also ask about SAFE Note Conversion
What affects SAFE Note Conversion the most?
Measured on this engine, Valuation cap is the dominant lever: moving it ±10 % shifts the SAFE stake at conversion across 4.6 % to 5.7 % — about 11.1 % of the headline, with SAFE investment next at ≈10.0 %. The ranked list in the sensitivity section is computed live, not asserted from a template.
Which matters more: safe investment or valuation cap?
By the numbers, Valuation cap: a ten-percent change in it moves the result ≈11.1 %, versus ≈10.0 % for SAFE investment. Spend your measuring effort in that order — precision on the weaker lever buys almost nothing.
What is a typical SAFE Note Conversion?
On the worked example above SAFE Note Conversion comes out at 5.1 %. 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 SAFE Note Conversion by hand?
Conversion basis = min(cap, round post × (1 − discount)); ownership = SAFE ÷ basis is the entire method. Work the inputs in that order — Discounted post = $16,997,821 × (1 − 18%) = $13,938,213; vs cap $6,174,258 → basis $6,174,258 — and you will reach 5.1 % on the default figures, the same number this tool prints.
What happens to SAFE Note Conversion if valuation cap changes by 10 %?
On these inputs a ±10 % change in valuation cap takes SAFE Note Conversion to 4.6 % against the 5.1 % example — around 11.1 % of the headline. The same test on every other field is in the sensitivity section.
Is the SAFE Note Conversion result of 5.1 % good or bad?
Good and bad are comparisons, so the honest test is three questions: where does your own SAFE Note Conversion sit against the 5.1 % reference above, how far would a plausible input error move it (≈11.1 % per ten percent on Valuation cap), and what does the alternative option compute to?
Can SAFE Note Conversion be negative or empty?
Yes, and that is informative rather than broken: a negative SAFE Note Conversion usually means the inputs encode an outflow or a shortfall, and the verdict band above labels exactly that situation instead of hiding it.
Should I use SAFE Note Conversion before launching?
Yes — a SAFE Note Conversion 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.
What if several SAFEs stack?
Each converts on its own best terms; cumulative dilution surprises founders who modeled one note at a time.
Do SAFEs accrue interest?
No — that is the point of the instrument; the economics live entirely in the conversion terms.
Do I need an account to use this SAFE Note Conversion 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.
Glossary for SAFE Note Conversion
- Conversion basis (effective post)
- $6,174,258 in the default SAFE Note Conversion calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Effective per-$ terms vs round investors
- 63.7 % for the SAFE Note Conversion worked case; it sits next to the main result because it carries context the headline leaves out.
- Round post at which cap and discount tie
- $7,529,583 in the default SAFE Note Conversion calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- SAFE stake at conversion
- The primary output of this tool: 5.1 % for the default inputs, computed exactly from Conversion basis = min(cap, round post × (1 − discount)); ownership = SAFE ÷ basis.
- Worked example
- The step-by-step substitution printed above, so the arithmetic can be re-derived by hand or in a spreadsheet.
- Verdict band
- The plain-language label — here “The valuation cap binds — the discount is a dead letter” — mapping the computed figure onto experience-based ranges for Business & Entrepreneurship.
- Sensitivity (±10 %)
- How far the SAFE Note Conversion 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 SAFE Note Conversion model comes from
Everything above runs on one stated formula, applied without hidden coefficients: Conversion basis = min(cap, round post × (1 − discount)); ownership = SAFE ÷ basis. Source of record: Y Combinator post-money SAFE (2018). 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. Nothing is smoothed, weighted or adjusted behind the scenes; where judgement enters, this page says so and names the input responsible.
What to do with your SAFE Note Conversion next
Sanity-check the magnitude after converting — most unit errors are off by a factor you can spot with a glance.
The audience here is anyone translating a figure between units or systems. Everything you need to defend the result — formula, substitution, sensitivity, source — is printed above, so the only remaining variable is the honesty of your inputs.