SAFE & Convertible Note Calculator

Both SAFEs and convertible notes are early-stage investment instruments that convert into equity later. But they have fundamental structural differences that affect both the investor and the founder.

Key differences:

• Debt vs. not-debt — A convertible note is a loan. It accrues interest, has a maturity date, and technically must be repaid if it never converts. A SAFE is not debt — it has no interest, no maturity, and no repayment obligation. If the company never raises another round, SAFE holders may get nothing.
• Interest accrual — Convertible notes accrue interest (typically 4-8% annually). When the note converts, both the principal and accrued interest convert into equity. This means note holders get slightly more shares than the principal alone would buy. SAFEs have no interest component.
• Maturity date — Notes have a maturity date (usually 18-24 months). If the company hasn't raised a priced round by then, the note is technically due. In practice, most notes get extended, but it gives investors leverage. SAFEs have no maturity — they sit there indefinitely until a conversion event.
• Legal complexity — Convertible notes require more documentation (promissory note, sometimes a note purchase agreement). SAFEs are typically a single, standardized 5-page document.
• Balance sheet treatment — Notes appear as liabilities on the balance sheet. SAFEs are treated as equity (or sometimes a hybrid) for accounting purposes. This matters for companies applying for loans or contracts that look at debt levels.

When to use which: SAFEs dominate in Silicon Valley and among YC-style startups. Convertible notes are more common in regions where investors want the security of a debt instrument, or when the company is further along and investors want interest accrual as extra compensation for the risk. Both can include a valuation cap and discount rate.

A valuation cap is the maximum company valuation at which a SAFE or convertible note will convert into equity. It protects early investors from getting a bad deal if the company raises its next round at a much higher valuation.

How it works in practice:

• Cap sets a ceiling on conversion price — Suppose you invest $100K with a $5M valuation cap. If the company raises its Series A at a $20M pre-money valuation, your SAFE doesn't convert at $20M. It converts as if the company were valued at $5M — your cap — giving you 4x more shares than a Series A investor would get per dollar invested.
• Cap price = valuation cap / pre-money shares — The conversion price under the cap is calculated by dividing the valuation cap by the number of shares outstanding before the new round. This gives you the effective price per share.
• The cap only matters if the next round valuation exceeds it — If the Series A is priced at $3M pre-money (below your $5M cap), the cap is irrelevant and you convert at the actual round price (possibly with a discount).

Why caps matter so much: The valuation cap is the single most important economic term in a SAFE. A $5M cap vs. a $10M cap means the early investor gets roughly 2x more shares for the same investment amount. For founders, a lower cap means giving up more ownership. For investors, a lower cap means more upside protection. Most SAFE negotiations center on this number.

Common cap ranges by stage: Pre-seed SAFEs typically have caps of $3M-$10M. Seed-stage SAFEs range from $8M-$25M. These numbers vary wildly by market conditions, geography, and sector. In hot markets, uncapped SAFEs (no valuation cap at all) are common but highly unfavorable to investors.

A discount rate gives the SAFE or note holder the right to convert at a price that is lower than what new investors pay in the next round. It rewards early investors for taking on more risk by investing before the company had a priced round.

The mechanics:

• Discount is applied to the next round price — If the Series A price per share is $10 and your SAFE has a 20% discount, you convert at $10 × (1 - 0.20) = $8.00 per share. You get 25% more shares per dollar invested compared to Series A investors.
• Common discount rates — Most SAFEs and convertible notes use a 15-25% discount. 20% is the most standard. Some aggressive investors negotiate 25-30%, while some hot-market SAFEs have no discount at all.
• Discount alone provides no upside protection — If you only have a discount (no cap), your conversion price rises proportionally with the next round valuation. A 20% discount on a $100M round still means a high conversion price. That's why most investors want both a cap and a discount.

Discount vs. cap — which applies? When a SAFE has both a valuation cap and a discount, the investor gets whichever produces the lower price per share (and therefore more shares). This calculator computes both paths side by side so you can see which one wins for your specific scenario.

Important nuance: The discount becomes irrelevant when the valuation cap is significantly below the next round valuation. For example, if your cap is $5M and the Series A is at $50M, the cap price will almost certainly be lower than the discounted price. The discount mainly matters when the next round is close to or below the cap, which happens more often than investors expect.

When a SAFE or convertible note includes both a valuation cap and a discount rate, the investor receives whichever conversion price is lower — meaning whichever path produces more shares. The investor always gets the better deal.

How to determine which wins:

• Calculate the cap price — Valuation cap divided by pre-money shares outstanding. Example: $5M cap / 10M shares = $0.50 per share.
• Calculate the discount price — Next round price per share multiplied by (1 minus discount rate). Example: $2.00 Series A price × (1 - 0.20) = $1.60 per share.
• Take the minimum — In this example, $0.50 (cap) beats $1.60 (discount), so the investor converts at $0.50. The cap wins by a wide margin because the Series A valuation ($20M implied) is far above the $5M cap.

When the discount wins instead: The discount path wins when the next round valuation is close to or below the valuation cap. For example, if the cap is $10M and the Series A is at $8M pre-money, the cap price might be $1.00 but the discount price (at 20% off) would be $0.80. In this case, the discount rate provides the better deal.

A practical rule of thumb: If the next round valuation is more than about 1.5x the cap, the cap will almost certainly produce the lower price. The discount only becomes the winning path when the company raises at a modest step-up from where you invested. This calculator shows both paths side by side so there is no guessing.

In 2018, Y Combinator introduced the post-money SAFE, which replaced the original pre-money SAFE as their standard template. The difference is subtle but has a major impact on dilution math.

Pre-money SAFE (original):

• The valuation cap applies to the pre-money valuation — the value of the company before the new investment comes in.
• SAFE investors and the new round investors dilute each other. The SAFE holder's final ownership depends on how much the new round raises.
• Founders cannot easily calculate how much dilution SAFEs will cause until the next round terms are finalized.

Post-money SAFE (YC standard since 2018):

• The valuation cap applies to the post-money valuation — the value of the company after including all SAFE investments.
• The SAFE holder's ownership percentage is calculable immediately: ownership = investment amount / post-money valuation cap. A $500K investment on a $5M post-money cap means exactly 10% ownership on a fully-diluted basis.
• Multiple SAFEs dilute each other and the founders, but the new round investors are not affected by pre-existing SAFEs.

Why this matters: On a post-money SAFE, every additional SAFE the company sells increases total dilution to the founders. If a company sells $1M of SAFEs on a $10M post-money cap, founders have given up 10%. If they sell another $1M SAFE at the same cap, founders have now given up 20%. With pre-money SAFEs, additional SAFEs dilute everyone (including other SAFE holders), making the math less predictable.

This calculator uses the pre-money SAFE framework, which is simpler and still widely used outside the YC ecosystem. The core cap-vs-discount conversion logic works the same regardless of pre-money or post-money structure.

An MFN (Most Favored Nation) clause is a provision sometimes included in SAFEs that protects early investors if the company later issues SAFEs with better terms. It essentially says: "if anyone after me gets a better deal, I automatically get those same terms."

How MFN works:

• Investor A gets an MFN SAFE — Suppose Investor A invests $250K on a SAFE with no valuation cap and no discount, but with an MFN clause.
• Company later issues a SAFE with better terms — Six months later, the company raises more money on a SAFE with a $6M valuation cap. The MFN clause triggers.
• Investor A can adopt the new terms — Investor A's SAFE is automatically amended to include the $6M cap, matching the better deal that the later investor received.

When MFN clauses appear: MFN SAFEs are most common when a company is raising its first capital and the valuation is genuinely uncertain. The first check-writer might accept an uncapped SAFE with MFN protection, knowing that the market will eventually set a cap as more investors come in.

Limitations: MFN only protects against future SAFEs — it does not apply to the terms of the priced round itself. If the Series A comes in at a valuation far above what the MFN investor hoped, they do not get a retroactive cap. MFN also does not typically apply to SAFEs issued to accelerators or as part of a different financing structure.

For founders: Be careful stacking MFN SAFEs. Every MFN SAFE you issue is a blank check on dilution — you will not know the true cost until you set final terms on a later SAFE or priced round.

SAFEs and priced rounds serve different purposes at different stages. Neither is universally better — the right choice depends on the company's stage, the amount being raised, and the leverage dynamics between founders and investors.

SAFEs make more sense when:

• Raising a small amount (under $2M) — The legal costs and time required for a priced round ($15-50K in legal fees, 4-8 weeks of negotiation) are disproportionate for small raises. A SAFE can be signed in a day with near-zero legal costs.
• The company is very early stage — When there is no revenue, no product-market fit, and no reliable way to set a valuation, a SAFE defers the valuation question to a future round when more data exists.
• Speed matters — If a company needs to close capital quickly (bridge financing, time-sensitive opportunity), SAFEs eliminate the back-and-forth of negotiating a full term sheet.
• Rolling close is desired — SAFEs let companies accept investments from multiple investors over weeks or months without coordinating a single close date.

Priced rounds make more sense when:

• Raising $3M+ from institutional investors — VCs investing larger checks typically want board seats, protective provisions, and clear cap table structure that only a priced round provides.
• The company has meaningful traction — With real revenue and growth data, there is no reason to defer the valuation. A priced round gives everyone certainty about ownership.
• SAFE debt is piling up — If a company has multiple outstanding SAFEs, the cap table becomes opaque. A priced round cleans everything up by converting all outstanding SAFEs and establishing clear ownership.
• Tax considerations — In some jurisdictions, a priced round lets investors claim tax benefits (like QSBS in the US) that may not be available with SAFEs.

The practical reality: Most startups use SAFEs for their pre-seed and seed raises, then switch to priced rounds at Series A and beyond. The transition typically happens when the raise size exceeds $2-3M and at least one lead investor wants formal governance rights.