What's the difference between a pre-money and post-money SAFE?

Pre-money SAFEs convert based on the cap before the SAFE investment counts. Post-money SAFEs (the current Y Combinator standard) include the SAFE itself in the cap, making dilution more predictable. Most new SAFEs are post-money.

Should I use a cap or a discount?

Most SAFEs have a cap only, discount only, or both. A cap protects the investor if your valuation skyrockets. A discount rewards early risk. Many investors prefer cap-only SAFEs for simplicity.

When does a SAFE convert?

SAFEs typically convert upon: (1) a priced equity round (Series A), (2) an acquisition, or (3) an IPO. Each scenario has different conversion mechanics specified in the SAFE.

Do SAFEs have expiration dates?

Unlike convertible notes, SAFEs don't have maturity dates. They stay outstanding until a conversion event happens, which could be years away.

How much dilution will my SAFE cause?

For post-money SAFEs: divide the SAFE amount by the cap. A $500K SAFE at a $5M cap means 10% dilution. For pre-money SAFEs, the math is more complex and depends on your Series A price.

SAFE Agreement Guide: How Startup SAFEs Work

What Is a SAFE Agreement?

A SAFE (Simple Agreement for Future Equity) is an investment contract that gives investors the right to receive equity in a future priced round. Created by Y Combinator in 2013, SAFEs have become the dominant instrument for early-stage startup fundraising, largely replacing convertible notes for pre-seed and seed investments.

The "simple" in SAFE is accurate—these agreements are typically five pages compared to the dozens of pages required for a priced equity round. SAFEs don't have interest rates, maturity dates, or the debt-like characteristics of convertible notes. They're cleaner, faster, and more founder-friendly.

When you raise money on a SAFE, you're not selling equity immediately. You're giving investors a contract that converts into equity during your next priced financing round (typically a Series A), at a price determined by that round's valuation with some investor-favorable adjustments.

How SAFEs Work: The Mechanics

Here's the basic flow of a SAFE investment:

Day 1: An investor gives you $500,000 in exchange for a SAFE with a $10 million valuation cap.

Day 1 to Series A: You use that money to build your company. The SAFE sits quietly—no payments, no interest, no action required.

Series A: You raise a Series A at a $20 million pre-money valuation. The SAFE now converts. Because your SAFE had a $10 million cap, the investor's $500,000 converts as if the valuation were $10 million (not $20 million), giving them 5% of the company instead of 2.5%.

The investor took early risk when your company was worth much less. The valuation cap rewards that risk by guaranteeing a maximum price for their conversion, regardless of how high your Series A valuation goes.

Key Terms You Need to Know

Valuation Cap

The maximum valuation at which the SAFE converts to equity. If your Series A valuation exceeds the cap, SAFE investors convert at the cap, getting more shares for their money. This is the most important term in any SAFE—it effectively sets the maximum price the investor pays for their eventual shares.

Discount Rate

A percentage discount SAFE investors receive on the Series A price. A 20% discount means if Series A investors pay $1.00 per share, SAFE investors pay $0.80 per share. Discounts can exist alongside or instead of valuation caps.

Post-Money vs. Pre-Money SAFEs

Y Combinator's current SAFE template is "post-money," meaning the cap includes the SAFE investment itself. This makes dilution calculations more predictable. Older "pre-money" SAFEs excluded the investment amount, making cap table math more complex. Most SAFEs issued today are post-money.

Pro Rata Rights

The right to invest in future rounds to maintain ownership percentage. Some SAFEs include pro rata rights; others don't. Investors value these rights because they can continue investing in winners.

MFN (Most Favored Nation)

A provision that allows SAFE investors to adopt the terms of any subsequent SAFE with better terms. If you issue a SAFE with a $10M cap, then later issue one with an $8M cap, MFN holders can switch to the $8M cap.

Types of SAFEs

Valuation Cap, No Discount

The most common structure. Investors get a maximum conversion price but no additional discount. Clean and simple.

Discount, No Valuation Cap

Investors get a percentage discount to the Series A price with no cap on valuation. This is more founder-friendly at high valuations but less common.

Valuation Cap AND Discount

Investors get the better of the cap OR the discount, not both. If the cap provides a better price than the discount, they use the cap, and vice versa.

MFN, No Cap or Discount

Used when you can't agree on valuation. The SAFE converts at whatever terms your next investor accepts. Rare and typically only used for very early checks.

SAFE vs. Convertible Note: Key Differences

Debt vs. Equity: Convertible notes are debt instruments that convert to equity. SAFEs are equity instruments from day one. This distinction matters for accounting, bankruptcy, and legal treatment.

Interest: Convertible notes accrue interest (typically 4-8% annually) that converts to additional shares. SAFEs have no interest.

Maturity Date: Convertible notes have a maturity date when they must be repaid or converted. SAFEs have no maturity—they sit indefinitely until a conversion event occurs.

Complexity: Convertible notes typically run 8-15 pages with more negotiated terms. SAFEs are 5-6 pages with standardized language.

Founder Preference: SAFEs are generally more founder-friendly due to no interest, no maturity pressure, and simpler terms.

Calculating SAFE Conversion: A Worked Example

Let's walk through a realistic scenario:

SAFE Round:

Investor A: $500,000 SAFE at $8M post-money cap
Investor B: $300,000 SAFE at $10M post-money cap
Investor C: $200,000 SAFE at $10M post-money cap with 20% discount

Series A:

$3M raised at $15M pre-money valuation
Post-money valuation: $18M
Price per share: $1.50

Conversion Calculations:

Investor A converts at the $8M cap (better than Series A price): $500,000 ÷ ($8M ÷ shares outstanding) = 6.25% ownership

Investor B converts at the $10M cap: $300,000 ÷ ($10M ÷ shares outstanding) = 3% ownership

Investor C compares cap vs. discount: 20% discount on $1.50 = $1.20 per share. The $10M cap might give a better or worse price depending on the cap table—whichever is lower applies.

The actual math involves more variables (option pool, multiple SAFE holders, etc.), but this illustrates the concept.

Common Mistakes to Avoid

Setting the Cap Too High

A valuation cap is not your company's valuation—it's the maximum price investors will pay. Setting it too high provides little benefit to early investors who took the most risk. This can make future fundraising harder and create misaligned expectations.

Setting the Cap Too Low

Conversely, a cap that's too low gives away excessive equity. If you raise $1M at a $4M cap, you've sold 25% of your company before you've priced a round. Be thoughtful about how much dilution you're accepting.

Stacking Too Many SAFEs

Each SAFE represents future dilution. If you raise $2M across multiple SAFEs at various caps, that's a lot of equity converting at your Series A. Model out the dilution before accepting more SAFE money.

Ignoring the Option Pool

Series A investors typically require an option pool (10-20% of the company) carved out before their investment. This dilutes everyone, including SAFE holders. Factor the option pool into your dilution calculations.

Not Using Standard Documents

YC's SAFE documents are free and widely accepted. Don't let investors propose heavily modified versions with unusual terms. Stick to standard documents to avoid hidden gotchas.

Forgetting Pro Rata Implications

If you grant pro rata rights to SAFE investors, they have the right to invest in your Series A. This can complicate your Series A negotiations and limit how much new investors can buy.

Negotiating SAFE Terms

What's Negotiable

The valuation cap is the primary negotiation point. Discount rates are somewhat negotiable. Pro rata rights can be included or excluded. Side letters for information rights or board observer seats are sometimes negotiated.

What's Not Negotiable

Don't modify the core SAFE mechanics. Conversion triggers, definition of equity financing, and other structural elements should remain standard. Any investor pushing for non-standard changes deserves extra scrutiny.

Multiple SAFEs at Different Caps

It's common to raise from multiple investors at different caps. Earlier investors might get lower caps (rewarding their earlier risk). Later investors might pay higher caps as the company has de-risked. Just keep the cap table manageable.

When SAFEs Convert

SAFEs typically convert upon:

Equity Financing: A priced round meeting a minimum threshold (often $1M or more). This is the expected conversion event.

Liquidity Event: An acquisition or IPO. SAFE holders either convert at the cap or receive a return of their investment (typically 1x), depending on the SAFE terms.

Dissolution: If the company shuts down, SAFE holders may receive their investment back if any assets remain, but they're typically behind creditors.

Actionable Advice

For Founders

Use Y Combinator's standard SAFE documents without modification. Model your dilution carefully before accepting investment—use a cap table tool to see how SAFEs affect ownership at various Series A scenarios. Don't optimize for the highest possible cap; optimize for the right investors at fair terms.

For Investors

Understand that SAFEs are not debt and have no downside protection beyond your pro rata return in a dissolution. The valuation cap is your primary protection against overpaying. Negotiate pro rata rights if you want to maintain your position in future rounds.

Build Your Cap Table Correctly

Track every SAFE with its key terms: investment amount, cap, discount, date, and investor. Your lawyer and future investors will need this information. Many founders use cap table software like Carta, Pulley, or AngelList to manage this.

Red Flags in SAFE Negotiations

Watch out for investors who:

Propose heavily modified SAFE documents
Insist on board seats for SAFE-sized investments
Require unusual control provisions or consent rights
Push for uncapped SAFEs in your first round
Demand full ratchet anti-dilution protection

These requests are non-standard and may indicate an investor who will be difficult to work with.

The Bottom Line

SAFEs have made early-stage fundraising faster, cheaper, and more founder-friendly. They eliminate the complexity of priced rounds while still providing a fair mechanism for investors to get equity.

But "simple" doesn't mean you can ignore the details. Understand your valuation cap, model your dilution, and use standard documents. A SAFE signed today determines how much of your company you own when you raise your Series A.

Take the time to get it right. The decisions you make in your first fundraise compound over the life of your company.