Why dilution matters to a first-time founder
Every funding round, option pool and convertible note adds new shares, and the effects compound. A founder who owns 60% and gives up 20% at seed, 20% at Series A and 10% for an option pool ends up with about 35%. Ignore that and you can lose majority control, fall below voting thresholds or receive far less at exit than you assumed. Modelling dilution early shapes how much you raise, at what price and when.
Examples of dilution
You own 50% before a round. The company issues new shares to an investor, and afterwards you own 40%. That dilution is ten percentage points. If the company is worth much more once the investment is in, 40% can be worth more in money than the old 50%. The percentage and the value are separate questions.
Common misunderstanding
People treat every bit of dilution as a loss, or they blame dilution for a deal that was really struck at a low price. The cap table shows you the percentage. The valuation is what tells you whether the smaller slice was a fair exchange.
When to use it
Work through the dilution before you agree a round, hire someone with shares, or set shares aside for future employees. If you do not know your percentage after the deal, you do not yet know what the deal is.