The above answers that it is $8M pre + $2M investment = $10M post with 20% owned by the investors is correct. Note that the supposedly brilliant investors on Shark Tank always calculate it incorrectly. If someone came to them saying I'm seeking $2M for 20%, they'd say "how can you justify a $10M valuation?" The proper answer would be ""I'm not, I'm justifying an $8M valuation, and your $2M would bring that up to $10M, with $2M in assets sitting in the bank."