"We'll invest $1M at a $4M pre-money." Sounds simple, but the difference between pre-money and post-money valuation determines how much of your company you are giving away. Get the math wrong and you could be diluted far more than you expected. This guide breaks down the formulas, shows real-world examples, covers option pool placement, and explains the subtle differences between priced rounds and post-money SAFEs.
The basic formula
Post-Money Valuation = Pre-Money Valuation + Investment Amount
Investor Ownership % = Investment Amount ÷ Post-Money Valuation
Pre-money valuation is the agreed value of the company before the investment. Post-money valuation is the value after the investment (pre-money + new money). The investor's ownership percentage is their investment divided by the post-money valuation.
Worked example
| Scenario A | Scenario B | |
|---|---|---|
| Pre-money valuation | $4,000,000 | $6,000,000 |
| Investment amount | $1,000,000 | $1,000,000 |
| Post-money valuation | $5,000,000 | $7,000,000 |
| Investor ownership | 20.0% | 14.3% |
| Founder ownership (after) | 80.0% | 85.7% |
Same investment, but a $2M difference in pre-money valuation changes founder ownership by nearly 6 percentage points. Over multiple rounds, these differences compound significantly.
The option pool trap
One of the most common negotiation traps involves where the option pool is carved from. Most investors will require you to establish (or increase) an employee option pool as a condition of the investment. The critical question is: is the option pool included in the pre-money or post-money valuation?
Pool in pre-money (investor-friendly)
The option pool is carved out of the founders' shares before the investor's money comes in. This effectively lowers the real pre-money valuation for founders. If the pre-money is $4M and includes a 15% option pool, the founder's effective pre-money is only $3.4M.
Pool in post-money (founder-friendly)
The option pool dilutes everyone equally — founders and investors. This preserves founder ownership but reduces the investor's effective ownership. This structure is less common but better for founders.
Negotiation tip
When an investor proposes a "pre-money" valuation, always ask: "Does that include the option pool?" If yes, calculate your effective pre-money by subtracting the pool. Then negotiate from there. You can also negotiate the pool size — most investors ask for 15–20%, but if you have already hired your key team, argue for 10–12%.
Post-money SAFEs: a different calculation
Y Combinator's post-money SAFE changed how many early-stage rounds are structured. Unlike a traditional priced round, a post-money SAFE defines the investor's ownership as a percentage of the post-money valuation including the SAFE itself but excluding the option pool.
Example: a $500K post-money SAFE with a $5M valuation cap gives the investor 10% ownership ($500K ÷ $5M). The option pool is on top of this, meaning founders are diluted by both the SAFE and the pool.
The advantage of post-money SAFEs is clarity — the investor knows exactly what percentage they are getting. The disadvantage for founders is that multiple SAFEs stack, and each one defines ownership based on the same post-money cap, which can lead to more total dilution than expected when they all convert in a priced round.
Multi-round dilution: how it compounds
| Round | Pre-money | Raised | Post-money | New investor % | Founder % (after) |
|---|---|---|---|---|---|
| Founding | — | — | — | — | 100.0% |
| Option pool (15%) | — | — | — | 15.0% | 85.0% |
| Seed | $4M | $1M | $5M | 20.0% | 68.0% |
| Series A | $15M | $5M | $20M | 25.0% | 51.0% |
A solo founder who starts at 100% ownership is down to ~51% after just a seed round and Series A. Understanding pre-money vs post-money is essential to modeling these scenarios accurately.
How eSignHub helps with fundraising math
eSignHub's cap table tools let you model fundraising scenarios — plug in different pre-money valuations, investment amounts, and option pool sizes to see exactly how dilution plays out. When you are ready to close, send your subscription agreements and shareholders' agreements through eSignHub for e-signature and track everything in one place.
Not financial advice
This guide is for educational purposes. Consult a qualified financial advisor and legal counsel before making investment decisions.
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