Free Tool

Startup Dilution Calculator
Free Tool

Enter your pre-money valuation, investment amount, and existing cap table to instantly calculate post-money valuation, new shares issued, and how each stakeholder is diluted.

Round details

$10.00M

$2.00M

10%

Current cap table

Founder A4.00M shares
Founder B3.00M shares
Angel Investors1.00M shares
$12.00M
Post-money valuation
$1.2500
Price per share
1.60M
New investor shares
10.56M
Total shares (post)

Ownership before & after

StakeholderBeforeAfterDilution
Founder A50.00%37.88%-12.12%
Founder B37.50%28.41%-9.09%
Angel Investors12.50%9.47%-3.03%
New investors0.00%15.15%
Option pool0.00%9.09%
Total100.00%100.00%

How startup dilution works

What is dilution?

Dilution occurs when a company issues new shares — through a funding round, option pool, or convertible note conversion — reducing existing shareholders' percentage ownership. Your share count stays the same, but the total shares outstanding increases, so each share represents a smaller portion of the company.

How is the post-money valuation calculated?

Post-money valuation = pre-money valuation + investment amount. If your company is valued at $10M pre-money and investors put in $2M, your post-money valuation is $12M and the new investors own $2M / $12M = 16.7% of the company.

What is an option pool and how does it dilute founders?

An option pool is a reserve of shares set aside for future employee equity grants. Investors typically require a 10–20% option pool to be created before the financing closes (the 'pre-money' method), which means existing shareholders — usually founders — bear the full dilution of the option pool creation.

What is a good dilution percentage per round?

Founders typically give up 15–25% of the company in a Seed round and 20–30% in a Series A. The exact percentage depends on the amount raised vs. the valuation. Keeping dilution below 25% per round helps founders maintain meaningful ownership through later stages.

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