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·2 min read

Post-money SAFE dilution at Series A: exact founder ownership impact

Model stacked post-money SAFEs, cap vs discount, MFN elections, and option pool expansion to see founder dilution at Series A close.

TL;DR outcome

  • Post-money SAFEs can take a larger ownership slice at Series A than founders expect, especially when caps are tight and pool top-up is pre-money.
  • MFN elections can materially improve conversion economics for eligible SAFE holders.
  • A pre-money option pool increase shifts dilution mostly to existing holders; post-money top-up shifts more to the new investor.

The question

When your SAFEs convert at Series A, how much of founder dilution comes from SAFEs themselves, how much from the pool expansion, and how much from new money?

Inputs that drive the answer

  • Share base before financing: founders, existing holders, and unallocated pool.
  • Each SAFE term set: amount, cap, discount, and MFN eligibility.
  • Series A terms: pre-money valuation and round size.
  • Option pool target and whether top-up is pre-money or post-money.

Interactive model

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How to read the output

  • Headline gives founder ownership after close versus pre-close.
  • Secondary cards show SAFE ownership and Series A ownership.
  • Worked example provides the exact share issuance and ownership checkpoints.
  • Breakpoints show cap-vs-discount crossover valuations and founder ownership thresholds.

Worked example interpretation

In the base preset, you can see the ownership transfer in sequence:

  1. SAFEs convert and reduce founder percentage first.
  2. Pool top-up then expands the denominator.
  3. Series A shares are issued at the priced-round share price.

That sequence is why founders often underestimate dilution when all three happen at once.

Common mistakes

  1. Modeling SAFEs one at a time instead of as a stacked conversion.
  2. Ignoring MFN elections in term comparisons.
  3. Treating pre-money and post-money pool top-ups as equivalent.
  4. Quoting dilution from dollars raised alone without conversion mechanics.

Checklist before signing the term sheet

  • Confirm SAFE stack terms in one table, not separate docs.
  • Confirm whether pool top-up is pre-money or post-money.
  • Run at least three valuation scenarios (downside/base/upside).
  • Share the exported table with founders and board before close.

References

Last updated

  • 2026-03-13: initial publication with stacked SAFE + MFN + pool top-up model.