VC Deal Math for Founders: The Complete Quick-Reference Guide
Every formula you need — pre/post-money, SAFEs, convertible notes, dilution, liquidation preferences, anti-dilution — with worked examples you can actually follow.
You're about to close a round. The term sheet has numbers on it. You nod along in the meeting, then Google furiously afterward.
We've all been there. This guide is the thing you bookmark so you stop Googling.
1. The Basics: Pre-Money, Post-Money, and What You're Selling
Two numbers define every priced round:
- Pre-money valuation — what the company is worth before the investment
- Post-money valuation — what it's worth after
The relationship is simple:
Post-Money = Pre-Money + Investment Amount
From there, everything else falls out:
Investor Ownership % = Investment ÷ Post-Money
Share Price = Pre-Money ÷ Pre-Money Shares Outstanding
New Shares Issued = Investment ÷ Share Price
Worked Example
You're raising $2M at an $8M pre-money valuation. You have 10,000,000 shares outstanding.
| Calculation | Result | |
|---|---|---|
| Post-money | $8M + $2M | $10M |
| Investor ownership | $2M ÷ $10M | 20% |
| Founder ownership | $8M ÷ $10M | 80% |
| Share price | $8M ÷ 10,000,000 | $0.80 |
| New shares issued | $2M ÷ $0.80 | 2,500,000 |
| Total shares after | 10,000,000 + 2,500,000 | 12,500,000 |
Sanity check: Investor holds 2,500,000 of 12,500,000 shares = 20%. ✓
2. The Option Pool Shuffle
This is the single most common way founders get diluted more than they expect.
Here's how it works: the investor says, "We want a 15% option pool." Sounds reasonable. But the pool gets created before the investment, meaning it comes out of the founders' share, not the investors'.
The stated pre-money includes the unissued option pool. So:
Effective Pre-Money = Stated Pre-Money − Option Pool Value
The investor's ownership is calculated on the post-money, which already bakes in the pool. They don't get diluted by it. You do.
Worked Example
Same deal: $2M investment, $8M stated pre-money, investor wants a 15% post-money option pool.
Post-money = $10M. A 15% pool = $1,500,000 worth of options.
| Without Pool | With Pool Shuffle | |
|---|---|---|
| Stated pre-money | $8M | $8M |
| Option pool value | — | $1,500,000 |
| Effective pre-money (founders) | $8M | $6,500,000 |
| Post-money | $10M | $10M |
| Investor owns | 20% | 20% |
| Option pool | 0% | 15% |
| Founders own | 80% | 65% |
The investor's 20% didn't change. The pool's 15% came entirely from you.
Your effective valuation isn't $8M. It's $6.5M. That's $1.5M in dilution the term sheet doesn't make obvious.
What to do: Negotiate the pool size down to what you'll actually need for the next 12–18 months of hiring. Every unnecessary percentage point comes directly from your pocket.
3. Post-Money SAFE Math
The post-money SAFE (YC's current standard) is elegant once you understand the core mechanic:
Ownership % = SAFE Investment ÷ Valuation Cap
That's it. The cap is a post-money number, so the math is a simple division.
The critical insight: multiple SAFEs dilute the founders, not each other. Each SAFE locks in its ownership percentage against the cap. If you sell two SAFEs, both percentages come from the founders' share.
Worked Example
You raise $500K on a post-money SAFE with a $5M cap.
Ownership at conversion = $500K ÷ $5M = 10%
Now say you raise another $300K SAFE at the same $5M cap:
Second SAFE ownership = $300K ÷ $5M = 6%
When both convert at a priced round:
| Holder | Ownership |
|---|---|
| SAFE investor 1 | 10% |
| SAFE investor 2 | 6% |
| Founders (pre-round) | 84% |
The founders absorbed all 16% of dilution. The two SAFE investors didn't dilute each other at all.
Discount SAFEs
Some SAFEs have a discount instead of (or in addition to) a cap. At conversion:
Conversion Price = Round Price × (1 − Discount %)
A 20% discount means the SAFE holder pays 80¢ on the dollar for shares. They convert at whichever method (cap or discount) gives them more shares — i.e., the lower effective price.
MFN (Most Favored Nation)
An MFN SAFE has no cap or discount but includes a clause: if you later issue a SAFE with better terms, the MFN holder can adopt those terms. It's a placeholder that upgrades automatically.
4. Pre-Money SAFEs (The Old Way)
Before YC introduced the post-money SAFE in 2018, SAFEs used a pre-money cap. The difference:
- Pre-money SAFE: Cap applies to the company's value before SAFE money is added. Investor ownership depends on how much total SAFE money was raised — you can't calculate the percentage until all SAFEs convert.
- Post-money SAFE: Cap applies to the company's value including SAFE money. Each investor's percentage is deterministic from day one.
Pre-money SAFEs created an awkward problem: every additional SAFE diluted the existing SAFE holders, not just the founders. Nobody could tell what they actually owned until the priced round. Founders couldn't model their cap table. Investors couldn't either.
The post-money SAFE fixed this by making ownership math simple and deterministic. That's why it became the standard. If someone hands you a pre-money SAFE today, ask why.
5. Convertible Note Math
Convertible notes are debt that converts to equity. They work similarly to SAFEs but add two complications: interest and a maturity date.
The interest accrues and increases the amount that converts into equity:
Conversion Amount = Principal × (1 + Interest Rate × Time in Years)
At conversion, the note converts at the lower of two prices (whichever gives the investor more shares):
Cap Price = Valuation Cap ÷ Pre-Money Shares
Discount Price = Round Share Price × (1 − Discount %)
The note converts at whichever price is lower.
Worked Example
- Note: $100,000 principal, 6% annual interest, 20% discount, $4M cap
- Converts after 18 months at a Series A with a $6M pre-money valuation
- Pre-money shares outstanding: 4,000,000
- Series A share price: $6M ÷ 4,000,000 = $1.50/share
Step 1: Accrued interest
$100,000 × (1 + 0.06 × 1.5) = $100,000 × 1.09 = $109,000 converts
Step 2: Cap price
$4,000,000 ÷ 4,000,000 = $1.00/share
Step 3: Discount price
$1.50 × (1 − 0.20) = $1.50 × 0.80 = $1.20/share
Step 4: Use the lower price → $1.00 (cap price wins)
Step 5: Shares issued
$109,000 ÷ $1.00 = 109,000 shares
If the investor had paid the Series A price: $109,000 ÷ $1.50 = 72,667 shares. The cap gave them 50% more shares — that's the reward for the early risk.
6. Dilution Across Rounds
Every round dilutes everyone who came before. The formula is straightforward:
Ownership After Round = Previous Ownership × (1 − New Investor %)
Stack this across rounds to see what you'll own at any future point.
Full Worked Waterfall: Seed → Series A → Series B
Starting point: Founder owns 100%.
Seed Round
- Raise $1M at $4M pre ($5M post)
- Create 10% option pool (pre-money shuffle)
- Investor gets: $1M ÷ $5M = 20%
| Holder | After Seed |
|---|---|
| Founder | 70% |
| Option pool | 10% |
| Seed investor | 20% |
Series A
- Raise $5M at $15M pre ($20M post)
- Expand option pool to 15% post-money (need 5% incremental, created pre-money)
- Series A investor gets: $5M ÷ $20M = 25%
Everyone from before gets diluted by the new 25% + 5% pool expansion = 30%:
| Holder | After Seed | × (1 − 0.30) | After A |
|---|---|---|---|
| Founder | 70% | × 0.70 | 49.0% |
| Seed option pool | 10% | × 0.70 | 7.0% |
| Seed investor | 20% | × 0.70 | 14.0% |
| New option pool expansion | — | — | 5.0% |
| Series A investor | — | — | 25.0% |
| Total | 100% | 100% |
Series B
- Raise $20M at $80M pre ($100M post)
- No new pool expansion
- Series B investor gets: $20M ÷ $100M = 20%
Everyone diluted by 20%:
| Holder | After A | × 0.80 | After B |
|---|---|---|---|
| Founder | 49.0% | × 0.80 | 39.2% |
| Seed option pool | 7.0% | × 0.80 | 5.6% |
| Seed investor | 14.0% | × 0.80 | 11.2% |
| Series A pool expansion | 5.0% | × 0.80 | 4.0% |
| Series A investor | 25.0% | × 0.80 | 20.0% |
| Series B investor | — | 20.0% | |
| Total | 100% | 100% |
The founder went from 100% → 70% → 49% → 39.2%. That's normal. At a $100M post-B valuation, 39.2% = $39.2M in value. Dilution isn't the enemy — dilution without value creation is.
7. Liquidation Preferences
Liquidation preferences determine who gets paid, and how much, when the company is sold.
1x Non-Participating (Standard)
The investor chooses the better of:
- (a) Getting their money back (1x their investment), OR
- (b) Converting to common stock and taking their pro-rata share
They don't get both. This is founder-friendly and the market standard.
1x Participating ("Double Dip")
The investor gets both:
- (a) Their money back first, AND THEN
- (b) Their pro-rata share of whatever's left
This is investor-friendly. It's called "double dip" because they dip into the proceeds twice.
Worked Example
- Exit price: $50M
- Series A: $10M invested for 25% ownership
- Founders + others: 75%
Scenario 1: 1x Non-Participating Preferred
Option A — take the liquidation preference: $10M Option B — convert and take 25% of $50M: $12.5M
Investor picks Option B ($12.5M). Founders get the other 75%: $37.5M.
Scenario 2: 1x Participating Preferred
Step 1 — investor gets $10M off the top. Remaining: $40M. Step 2 — investor gets 25% of the remaining $40M: $10M. Investor total: $20M. Founders get: $30M.
| Non-Participating | Participating | |
|---|---|---|
| Investor gets | $12.5M | $20.0M |
| Founders get | $37.5M | $30.0M |
That's a $7.5M difference on the same exit. Participating preferences matter.
When Non-Participating Hurts
At a $30M exit (lower outcome):
- Non-participating: Investor picks max of $10M vs 25% × $30M = $7.5M → takes $10M. Founders get $20M.
- Participating: $10M + 25% × $20M = $10M + $5M = $15M. Founders get $15M.
The lower the exit, the more participating preferences bite.
Multiples
A 2x liquidation preference means the investor gets $20M back before anyone else sees a dime (on a $10M investment). Multiples above 1x are uncommon in healthy markets and a sign of a tough negotiation. Push back hard.
8. Anti-Dilution Protection
Anti-dilution provisions protect investors when you raise a future round at a lower valuation (a "down round"). They adjust the investor's conversion price downward, giving them more shares.
Full Ratchet
The conversion price drops to the new round's price, period. Brutal for founders.
New Conversion Price = Down Round Price
Broad-Based Weighted Average (Standard)
The most common (and fairest) formula:
Adjusted Price = Old Price × (A + B) ÷ (A + C)
Where:
- A = total shares outstanding before the new round (fully diluted)
- B = shares that would have been issued at the old price (New Money ÷ Old Price)
- C = shares actually issued at the new (lower) price (New Money ÷ New Price)
Narrow-Based Weighted Average
Same formula, but A only counts the specific investor's series of preferred stock, not all shares outstanding. This produces a lower adjusted price (more favorable to the investor) than broad-based.
Down Round Worked Example
- Series A: $5M invested at $1.00/share → 5,000,000 shares
- Total shares outstanding (fully diluted): 10,000,000
- Series B (down round): $3M raised at $0.50/share
Full Ratchet:
New conversion price = $0.50. Series A investor now has:
$5M ÷ $0.50 = 10,000,000 shares (doubled from 5M)
Broad-Based Weighted Average:
- A = 10,000,000 (total shares before B)
- B = $3,000,000 ÷ $1.00 = 3,000,000
- C = $3,000,000 ÷ $0.50 = 6,000,000
Adjusted Price = $1.00 × (10,000,000 + 3,000,000) ÷ (10,000,000 + 6,000,000)
= $1.00 × 13,000,000 ÷ 16,000,000
= $0.8125
Series A shares after adjustment: $5,000,000 ÷ $0.8125 = 6,153,846 shares
| Method | Adjusted Price | Series A Shares | Extra Shares |
|---|---|---|---|
| No protection | $1.00 | 5,000,000 | — |
| Broad-based weighted avg | $0.8125 | 6,153,846 | +1,153,846 |
| Full ratchet | $0.50 | 10,000,000 | +5,000,000 |
Full ratchet gave the Series A investor 5M extra shares. Broad-based weighted average gave them ~1.15M. That difference comes directly from the founders. Always push for broad-based weighted average.
9. Pro Rata Rights & Pay-to-Play
Pro Rata Rights
Pro rata gives an existing investor the right (not obligation) to invest in future rounds to maintain their ownership percentage.
Pro Rata Amount = Investor Ownership % × New Round Size
If an investor owns 15% and you're raising a $10M Series B, their pro rata allocation is:
15% × $10M = $1.5M
If they invest $1.5M, they maintain 15% (before dilution from the rest of the round). If they pass, they get diluted like everyone else.
Pro rata is valuable in hot rounds. It guarantees a seat at the table when other investors want in and the round is oversubscribed.
Pay-to-Play
Pay-to-play provisions say: if you don't exercise your pro rata (or some minimum portion), you lose something — typically your preferred stock converts to common stock.
That means losing:
- Liquidation preference
- Anti-dilution protection
- Any other preferred-stock rights
It's a forcing mechanism. It keeps investors from sitting on their preferences while refusing to support the company in a tough round. It's most common (and most useful) in down rounds.
For founders: Pay-to-play is generally founder-friendly. It prevents zombie investors from blocking deals while hoarding liquidation preferences they haven't earned through continued support.
10. Quick Reference Cheat Sheet
Cut this out and tape it to your monitor.
Valuation
| Formula | |
|---|---|
| Post-Money | Pre-Money + Investment |
| Investor % | Investment ÷ Post-Money |
| Share Price | Pre-Money ÷ Shares Outstanding |
| Shares Issued | Investment ÷ Share Price |
Option Pool
| Formula | |
|---|---|
| Effective Pre-Money | Stated Pre-Money − Pool Value |
| Pool Value | Pool % × Post-Money |
Post-Money SAFE
| Formula | |
|---|---|
| Ownership % | SAFE Amount ÷ Valuation Cap |
| Discount Conversion Price | Round Price × (1 − Discount %) |
Convertible Notes
| Formula | |
|---|---|
| Conversion Amount | Principal × (1 + Rate × Years) |
| Cap Price | Cap ÷ Pre-Money Shares |
| Discount Price | Round Price × (1 − Discount %) |
| Shares Issued | Conversion Amount ÷ min(Cap Price, Discount Price) |
Dilution
| Formula | |
|---|---|
| Ownership After | Previous % × (1 − New Investor %) |
Liquidation Preferences
| Formula | |
|---|---|
| Non-Participating | max(Preference, Ownership % × Exit) |
| Participating | Preference + Ownership % × (Exit − Total Preferences) |
Anti-Dilution (Broad-Based Weighted Average)
| Formula | |
|---|---|
| Adjusted Price | Old Price × (A + B) ÷ (A + C) |
| A | Total shares outstanding (fully diluted) |
| B | New $ ÷ Old Price |
| C | New $ ÷ New Price |
Pro Rata
| Formula | |
|---|---|
| Pro Rata Amount | Ownership % × New Round Size |
The Bottom Line
Deal math isn't hard. It's just not taught anywhere, so it feels opaque the first time you see a term sheet.
The founders who understand these formulas don't just negotiate better — they make better decisions about when to raise, how much to raise, and what terms actually matter versus what's just noise.
Bookmark this page. Pull it up before your next term sheet negotiation. And if the math on a term sheet doesn't add up — now you'll know.
Need help reviewing a term sheet or modeling your cap table? Flux works with founders at every stage. Reach out — we like talking deal math.
Need legal guidance for your startup?
Book a free intro call and see how Flux can help.
Book a Free Call