Pre-money, post-money & dilution
A round is priced by two numbers: post-money = pre-money + investment, and the new investor owns investment ÷ post-money. Every existing holder is then diluted by the pre ÷ post ratio. The Shark-Tank lens: an offer of “X dollars for Y%” implies post-money = X ÷ Y% and pre-money = post − X.
Post-money (after Round 1)A$10.0m
Founder stake 80.0%Round 1 investor 20.0%
Round 1 pre-moneyA$8.0m
Round 1 investmentA$2.0m
Post-money is A$10.0m, so the round 1 investor owns 20.0% and the founders keep 80.0%. A bigger cheque at the same pre-money hands the investor a larger slice.
Scope: priced equity only. SAFEs, convertible notes, option pools, and anti-dilution are out of scope.
Try this. Raise more at the same pre-money (push Round 1 investment up while pre-money holds) and watch the founder slice shrink. Then turn on Round 2: a strong up-round (high Round 2 pre-money) dilutes the founder far less than a flat or down round at the same investment.