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Pro-rata Investment Calculator

How much an existing investor needs to put in at the next round to maintain their ownership percentage. Useful for both founders modeling investor behavior and investors deciding whether to follow on.
Pro-rata investment to maintain percentage
$640K
Post-money valuation
$38.0M
Ownership if you skip
6.32%
Dilution if you skip
1.68%
How it worksTo maintain your ownership %, you need to invest your pro-rata share of the new round (your % × round size). At 8.0% ownership and a $8.0M round, that's $640K.
When to exercise pro-rata
  • • If the company is performing well and the next round price is justified.
  • • If you have capital reserves and following on is a strategic priority.
  • • Decline if the next round is a flat or down round and you no longer have conviction.
  • • Lead investors usually have pro-rata rights; small angels often don't (or shouldn't expect to).

What is the pro-rata investment calculator?

Pro-rata rights let an existing investor put in enough money at the next round to maintain their current ownership percentage. Without pro-rata, every new round dilutes them.

The math is simple: pro-rata investment = current ownership % × new round size.

Why this matters for founders & operators

For investors, pro-rata is a major part of total returns. The best fund returns historically come from doubling down on winners — pro-rata is the mechanic that makes that possible.

For founders, pro-rata determines how much room you have for new investors at each round. If existing investors take significant pro-rata, the new round has less allocation available — which can be good (signals confidence) or bad (limits new lead options).

How to use this calculator

  1. 1
    Enter current ownership

    Your fully-diluted ownership today, post any prior dilution.

  2. 2
    Enter the next round terms

    Pre-money valuation and round size from the term sheet.

  3. 3
    Read the pro-rata investment

    How much you (or the investor you're modeling) need to put in to maintain percentage.

  4. 4
    Compare to dilution if skipped

    If you don't take pro-rata, your ownership drops by the dilution percentage. Sometimes that's worth it; sometimes not.

FAQ

Do all investors have pro-rata rights?+
Lead investors at every round typically do. Smaller angels and follow-on investors sometimes don't, depending on the term sheet's 'major investor' threshold.
What's a 'super pro-rata'?+
Super pro-rata gives an investor the right to invest MORE than their pro-rata share at the next round. Less common, controversial, and usually only granted to top-tier leads.
Should I always exercise my pro-rata?+
No. Exercise when you still have conviction in the company and have capital. Decline when the company is struggling or the new round is overpriced.
Do pro-rata rights survive forever?+
Usually they sunset at IPO or at a specific round threshold (e.g., 'pro-rata rights apply until Series B+'). Negotiable.