Come up with "weak", "normal", and "blowout" revenue numbers for 1 year, 2 years, 4 years. You'll probably have to both ask your prospective employer and do a little research, but these aren't sensitive numbers. If the startup you're applying for can't tell you what "the number" is, they're doing it wrong, and you should be wary. You only really need one set of numbers; then discount (say 50%) for "weak", and premium (say 100%) for "blowout".
Now you have a spreadsheet with 3 columns for the years by 3 rows for the scenarios.
Do another grid below that for "deal size" (again by the three years). Instead of "weak", "normal", "blowout", do "2x", "5x", "10x" (crazy successful startups beat 10x, but it's in reality silly to do financial planning based even on a 5x return). Fill the cells in the grid with revenue x2, x5, x10; that's total deal size.
Subtract from each cell the amount the company has taken in funding (prefs might be even worse than that, but just assume 1x).
Now take the % of the company you're getting in equity and work out your take.
Divide each of those "take home" cells by 4, because that's how long you have to work to get all your shares.
If you want to get a little fancier:
If they haven't taken an A round, ding your equity by some % in year 1.
If they haven't taken a B round, ding your equity by some % in year 2.
Come up with "weak", "normal", and "blowout" revenue numbers for 1 year, 2 years, 4 years. You'll probably have to both ask your prospective employer and do a little research, but these aren't sensitive numbers. If the startup you're applying for can't tell you what "the number" is, they're doing it wrong, and you should be wary. You only really need one set of numbers; then discount (say 50%) for "weak", and premium (say 100%) for "blowout".
Now you have a spreadsheet with 3 columns for the years by 3 rows for the scenarios.
Do another grid below that for "deal size" (again by the three years). Instead of "weak", "normal", "blowout", do "2x", "5x", "10x" (crazy successful startups beat 10x, but it's in reality silly to do financial planning based even on a 5x return). Fill the cells in the grid with revenue x2, x5, x10; that's total deal size.
Subtract from each cell the amount the company has taken in funding (prefs might be even worse than that, but just assume 1x).
Now take the % of the company you're getting in equity and work out your take.
Divide each of those "take home" cells by 4, because that's how long you have to work to get all your shares.
If you want to get a little fancier:
If they haven't taken an A round, ding your equity by some % in year 1.
If they haven't taken a B round, ding your equity by some % in year 2.