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SAFE Note Conversion Calculator

Simulate SAFE note conversions by calculating the exact share price an angel investor receives at a Series A round, including both the Valuation Cap and Discount methods.

Original SAFE Terms

$
$
%

Hypothetical Series A Details

$
Logic Engine: Synthetically generating standard VC Share Price: $1.00. The algorithm executes a dual-path calculation testing the $5,000,000.00 Valuation threshold against the 20% discount vector to output maximum share dilution.

SAFE Conversion Price

$0.50
Determined via: Valuation Cap method

Total Shares Granted

200,000
Post-Series A Ownership: 1.96%

Pricing Vector Comparison

Standard VC Price:$1.00
Theoretical Discount Price:$0.80
Theoretical Cap Price:$0.50
Executed Winner (Lowest):$0.50
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What is The Mathematics of SAFE Notes?

Introduced by Y-Combinator in 2013, the Simple Agreement for Future Equity (SAFE) is the absolute standard for early-stage startup investing. It is not debt and not equity — it is a mathematical warrant that forces a startup to grant the investor shares at a systematically cheaper price during the Series A round.

Mathematical Foundation

Conversion Price=min⁡(Valuation CapTotal Shares,  Series A Price×(1−Discount))\text{Conversion Price} = \min \left( \frac{\text{Valuation Cap}}{\text{Total Shares}}, \; \text{Series A Price} \times (1 - \text{Discount}) \right)
Valuation Cap\text{Valuation Cap}= The maximum valuation at which the investor's money converts. Protects the angel if the startup explodes in value before Series A.
Discount\text{Discount}= A flat percentage off the Series A price if the startup's valuation does not hit the Cap threshold.

Laws & Principles

  • The Lower Of Rule: If a SAFE has both a Cap and a Discount, the investor always converts at whichever method produces the cheapest share price — maximizing equity for the early risk-taker.
  • Zero Downside Protection: If the startup fails before a priced round, the SAFE is legally worthless. The investor loses 100% of cash with no debt claim.
  • Pre- vs Post-Money SAFEs: Since 2018, YC defaults to Post-Money SAFEs, which are more dilutive to founders because the investor's ownership percentage is locked in at signing.

Step-by-Step Example Walkthrough

" $100k SAFE with $5M Cap and 20% discount. Series A: $10M pre-money, 10M shares outstanding. "

  1. Series A share price: $10M / 10M shares = $1.00/share
  2. Discount method: $1.00 x (1 - 0.20) = $0.80/share
  3. Cap method: $5M / 10M shares = $0.50/share
  4. Winner (lower): $0.50 via Cap method
Final Result: $100k / $0.50 = 200,000 shares. At the standard VC price they would have gotten only 100,000 shares.

Quick Answer: How does the SAFE Note Conversion Calculator work?

This tool simulates the SAFE note conversion at a hypothetical Series A priced round. Enter the original SAFE terms (investment amount, valuation cap, discount rate) and the Series A details (pre-money valuation, shares outstanding). The calculator runs both the Cap method and Discount method, selects the winner per the "Lower Of" rule, and outputs your conversion price, shares granted, and post-Series A ownership percentage — instantly in your browser.

SAFE Conversion Formula — Step by Step

Step 1 — Calculate Series A Share Price (Baseline)

Series A Price = Pre-Money Valuation ÷ Total Shares Outstanding

Step 2 — Test Both SAFE Mechanisms

Cap Price = Valuation Cap ÷ Total Shares

Discount Price = Series A Price × (1 − Discount %)

Step 3 — Select the Lower Price (Investor Wins)

Conversion Price = min(Cap Price, Discount Price)

Step 4 — Calculate Shares Granted

Shares = Investment Amount ÷ Conversion Price

Real-World Scenarios

✓ Cap Wins — Rocket Ship Startup

Valuation dramatically exceeded the cap at Series A

  1. Angel SAFE: $250,000 | $5M Cap | 20% Discount
  2. Series A: $25M pre-money, 10M shares
  3. Series A Price: $25M / 10M = $2.50/share
  4. Discount Price: $2.50 × 0.80 = $2.00/share
  5. Cap Price: $5M / 10M = $0.50/share (wins!)
  6. Shares: $250k / $0.50 = 500,000 shares

→ The Cap protects the angel massively. At the standard $2.50 VC price, they'd only get 100,000 shares. The cap gives them 5x more equity for the same investment.

△ Discount Wins — Modest Valuation Growth

Company grew, but not above the cap threshold

  1. Angel SAFE: $100,000 | $5M Cap | 20% Discount
  2. Series A: $4M pre-money, 5M shares
  3. Series A Price: $4M / 5M = $0.80/share
  4. Discount Price: $0.80 × 0.80 = $0.64/share (wins!)
  5. Cap Price: $5M / 5M = $1.00/share (worse)
  6. Shares: $100k / $0.64 = 156,250 shares

→ The discount wins when the Series A valuation is below the cap. The angel still gets a 20% better price than the institutional VC, rewarding their early-stage risk.

SAFE Note Terms — Quick Reference

SAFE Term Typical Range Effect
Valuation Cap$1M – $20MLower cap = more founder dilution if startup succeeds
Discount Rate10% – 30%Higher discount = cheaper price at conversion
No Cap, No DiscountRareInvestor converts at exact Series A price — no benefit
Post-Money SAFEYC Standard (2018+)Investor's % locked in — founder absorbs all dilution
Pre-Money SAFELegacy (pre-2018)Dilution shared between investor and founder at Series A

Pro Tips & Founder Pitfalls

Do This

  • ✓Model your cap table before signing multiple SAFEs. Each SAFE is a future dilution event. Stack several $500k SAFEs with low caps and your Series A equity can be decimated by conversion before the VC even writes their check.
  • ✓Set the cap at 3-5x your current estimated value. A cap set too low locks in massive dilution if you succeed. A cap set too high offers no meaningful protection to the investor. The 3-5x multiple is the market-standard compromise.

Avoid This

  • ✗Do not sign post-money SAFEs if you plan to raise multiple SAFE rounds. Post-money SAFEs lock investors' ownership percentages, meaning all dilution from subsequent SAFEs falls entirely on the founders. A string of post-money SAFEs can leave founders with catastrophic equity depletion before Series A.
  • ✗Do not assume a SAFE has investor protections in bankruptcy. Unlike convertible notes (which are debt), SAFEs have zero legal claim on company assets if the startup fails. Investors must explicitly understand this before signing — they lose 100% with no recourse.

Frequently Asked Questions

What happens to a SAFE if the startup never raises a Series A?

If the startup is acquired before a Series A, the SAFE typically converts at the cap price or the investor may be entitled to a return premium (commonly 1-2x their investment) depending on the SAFE's acquisition terms. If the startup goes bankrupt with no acquisition, the SAFE is legally worthless — it is not debt, so investors have no creditor priority. This is the fundamental "unlimited upside, total downside" risk structure of early-stage angel investing.

What's the difference between a SAFE and a convertible note?

A convertible note is debt with a maturity date and interest rate. If the startup does not raise a qualifying round before maturity, the note may be legally "called" — investors can demand repayment and potentially bankrupt the company. A SAFE has no maturity date and no interest accrual. It is simpler, cheaper to issue, and removes the existential threat of a maturity deadline. Most founders prefer SAFEs for this reason; most sophisticated investors understand the tradeoff.

Can founders negotiate the valuation cap on a SAFE?

Yes — the valuation cap is fully negotiable. It is not set by law but by the supply-and-demand dynamics of the fundraise. A founder with high traction and multiple interested investors can negotiate a higher cap (less dilution). A pre-revenue startup with an unproven idea will accept a lower cap to attract capital. The market standard for angel-stage SAFEs is caps at 3-5x the startup's current estimated value, but cap structures vary widely by sector and deal heat.

Why does this calculator use "Total Outstanding Shares" instead of a post-money valuation?

The SAFE conversion price formula divides the valuation cap by the total shares outstanding (the "Company Capitalization"), not a post-money valuation. This is because share price = value / shares. The total outstanding share count determines what each share is worth at the Series A price. Using shares instead of a post-money valuation ensures the math is consistent whether the Series A includes new share issuances or not, and matches the Y-Combinator SAFE legal standard.

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