How much should I invest in a single angel check?

A common practitioner convention is at most 1% of investable net worth per check, within a total private-bet allocation near 5% — each check carrying an equal follow-on reserve. The arithmetic keeps any single zero boring, which is what makes a power-law asset class survivable.

What percentage of net worth should go to angel investing?

Around 5% of investable net worth is the common ceiling for the whole private book — conservative desks run 3%, professionals with strong dealflow more. Past the line, one bad vintage stops being a lesson and starts being a story.

Should I reserve money for follow-on rounds?

Yes — house practice is a 1:1 reserve per check. Winners raise again, and pro-rata rights in them are the early check's main prize; without a reserve you dilute exactly where you least want to.

Angel Check Sizing Calculator — Position Size Against Your Net Worth

The balance sheet, after wiring

The sizing, line by line

Where this check puts you

Your private-bet allocation at every check size, reserve included. The dashed line is your book line; the crossing is the biggest check that stays inside it. Hover to explore.

What zeros cost at this size

Sizing discipline

How we calculate

What is included

The real commitment is the check plus its follow-on reserve (1:1 when the seg is on — the next round arrives whether you budgeted or not). Allocation after = (existing book + commitment) ÷ net worth, read against the book line (5% by convention, adjustable) and the per-check line (a fifth of the book line — 1% at defaults). The zeros table prices the honest scenario: in a power-law asset class, most checks return nothing, and the whole design question is whether that costs you sleep or shrugs.

What is estimated or left out

The instrument sizes; it does not select. Valuation, terms, the founder, and whether angel investing suits you at all are outside it. Staged deployment matters as much as size — ten checks over three vintages beats three checks this quarter at the same total. Marks on the existing book are taken at cost; if you counted the last round’s valuation, re-enter at what you wired.

The formula, in plain words

commitment  = check × (1 + reserve)         reserve ∈ {0, 1}
allocation  = (book + commitment) ÷ net worth
book line   = 5% of net worth (yours to change)
check line  = book line ÷ 5  — one enthusiasm, capped
max check   = (line × net worth − book) ÷ (1 + reserve)

Common questions

How much should I invest in one angel deal?: Practitioner convention: no more than about 1% of investable net worth per check, inside a private-bet book capped near 5% — and each check carries an equal follow-on reserve. At $800k net worth that means $4–8k checks, not the $25k minimum many syndicates float. The minimum being higher than your size is an answer, not an obstacle.
Why reserve for follow-ons at all?: Because the winners raise again, and pro-rata is the one advantage the early check buys. Without a reserve you either dilute in your best positions — giving away the exact power-law tail you invested for — or scramble for cash at the worst moment. Reserving 1:1 up front makes the real cost of the deal visible today.
What returns should I expect from angel investing?: A power law: in a typical portfolio most checks go to zero or near it, a few return the fund, and one — if you’re both good and lucky — pays for the graveyard. That only works across 15–30 checks over several years. Below ten checks it isn’t a portfolio, it’s a lottery ticket with paperwork.

Angel Check Sizing