Startup Investment Calculator

📘 What This Calculator Estimates

This calculator models a single angel or seed investment from check to exit. It takes your check size, the company's pre-money valuation, an assumed exit value, and your expected dilution before exit, then returns your ownership percentage, your diluted ownership, exit proceeds, ROI multiple, IRR over a 7-year horizon, and four exit scenarios (bear, base, bull, and home run).

The mechanics: your ownership is your check divided by the post-money valuation. Future rounds dilute that stake — the dilution slider (10-70%) estimates how much of your position later investors, option pool top-ups, and new shares will consume before the exit. The scenarios then show what your diluted stake is worth at 50% of your exit assumption, the base case, 3x, and 10x.

How to read the results: an IRR above 20-25% is the working bar for early-stage checks, which means the exit multiple needs to clear roughly 3-4x over seven years. If the base case shows a multiple below 2x, the round is priced for a modest outcome — fine for income investors, wrong for angel portfolios that depend on a few 10x winners. Always stress-test the exit value: small changes in exit assumptions move proceeds far more than small changes in check size.

Use Cases

• Angels sizing a check: see how much ownership your typical check buys at realistic valuations.
• Comparing rounds: run the same check size through two different valuations and dilution assumptions.
• Syndicate participation: model what a smaller pro-rata follow-on does to your blended position.
• Setting expectations: the scenario table makes the power-law reality of angel investing concrete before you write the check.

Tip: pair the math with momentum. GitDealFlow tracks commit velocity, contributor growth, and repository expansion across 4,200+ startups and sends five names every Sunday — engineering acceleration typically precedes fundraises by 21-47 days, which is exactly the window where valuations are still reasonable.

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❓ Frequently Asked Questions

What is dilution and why does the slider matter?

Dilution is the reduction in your ownership percentage caused by new shares issued in later rounds and option pool top-ups. A 30% dilution assumption means your pre-exit stake shrinks by roughly a third. Early-stage investors typically model 20-50% total dilution between their entry and a Series B/C exit.

Why does the calculator use a 7-year horizon?

Angel and seed investments are illiquid and typically return between 7 and 10 years after the check is written. Seven years is a standard midpoint for computing an IRR on early-stage venture positions.

Is this calculator financial advice?

No. It is a scenario tool for education and planning. Real outcomes depend on liquidation preferences, participation rights, follow-on rounds, and market conditions — review any investment with qualified advisors.