SAFE dilution calculator
Work out what your SAFEs actually convert into at a priced round, and what you own once the new money and the option pool are in. Handles pre-money and post-money SAFEs, valuation caps, discounts, several SAFEs at once, and a pool refresh.
Your cap table today
Fully diluted shares before this round: founders, issued options, everything already granted.
Fully diluted today: 10,000,000 shares
SAFEs outstanding
Every SAFE that converts at this round. Leave the cap or the discount blank if the instrument does not have one.
The priced round
The equity round the SAFEs convert into.
Pre-money $12,000,000 · post-money $15,000,000
Set to 0 for no refresh. The top-up comes out of the pre-money.
Ownership after the round
Percentages are of the fully diluted cap table, including the unallocated option pool.
| Holder | Before | Shares after | After | Change |
|---|---|---|---|---|
| Founders | 90.00% | 9,000,000 | 65.17% | −24.83 pts |
| Option pool (unallocated) | 10.00% | 1,380,952 | 10.00% | −0.00 pts |
| Angel SAFEconverted | — | 666,667 | 4.83% | new |
| New investors (this round) | — | 2,761,905 | 20.00% | new |
How each SAFE converted
The cap price and the discount price are both shown. The lower one is the price the investor converts at.
| SAFE | Cap price | Discount price | Converts at | Owns | On paper |
|---|---|---|---|---|---|
| Angel SAFE$500,000 · post-money | $0.7500 | none | $0.7500on the cap | 4.83%666,667 shares | $724,1381.45× the money in |
“On paper” values the converted shares at this round's price. It is not cash, not realised, and not a prediction of anything.
Where the pool landed
- Before
- 1,000,000
- Created now
- 380,952
- After
- 1,380,95210.00%
This is an estimate, not advice. It is a model of the standard SAFE mechanics applied to the numbers you typed, not legal, tax or financial advice, and it does not read your actual documents. A real conversion follows the exact wording of what you signed. Have your lawyer check the numbers before you sign or countersign anything.
Pre-money and post-money SAFEs dilute you differently
The two instruments share a name, a cap and a discount, and then part company on the one question that decides your ownership: which cap table is the conversion price measured against?
Post-money SAFE
The standard since 2018
The holder gets amount divided by cap of the company as it stands after all SAFEs convert and before the new money arrives. That percentage is fixed the day the paper is signed, so a second SAFE does not touch the first one — it comes out of the founders instead. Sign four of them and you have sold four separate slices of yourself.
Pre-money SAFE
The 2013 to 2018 paper
The conversion price is measured against a cap table that excludes every SAFE, so each holder is priced as if the others did not exist. When they all convert together, everyone lands lower than their headline percentage, and the more SAFEs there are, the further the gap opens.
A worked example, using the numbers this calculator ships with: one SAFE of $500,000 on an $8,000,000 cap converting into a $3,000,000 round. On post-money paper the holder is entitled to 6.25% of the pre-financing company. On pre-money paper the same money and the same cap land near 5.88%, because the cap price is struck against a share count that pretends the SAFE is not there. Change the SAFE type in the form above and watch the founder row move.
The option pool is the part founders miss
Almost every term sheet asks for a pool top-up as a condition of the round, and almost every one of them creates it out of the pre-money. That means the pool is not paid for by the investor buying in — it dilutes the people who were already there. Set the target pool above to 0 and then to 10% and watch which rows move: the new investors hold exactly the same percentage either way.
What this calculator assumes
Some parts of a conversion are genuinely ambiguous until you read the signed documents. Rather than pick quietly, here is every choice this model makes.
- The option pool top-up is created out of the pre-money, the standard treatment. Existing shareholders carry it; the incoming investors do not.
- A post-money SAFE converts at cap divided by a capitalisation that includes every converting SAFE and excludes the pool increase made in connection with this round.
- A pre-money SAFE converts at cap divided by a capitalisation that excludes all SAFEs and includes the pool increase promised for this round.
- Cap and discount are compared, and the lower resulting price per share is used.
- The pool target is read as a percentage of the fully diluted cap table after the round. If the pool already clears the target, no new shares are created — nothing is ever clawed back.
- Shares are kept as exact fractions rather than rounded to whole shares, so percentages add to 100 instead of drifting.
What it does not model
These change real outcomes and are deliberately absent, so nothing here should be read as a complete picture of a financing.
- Liquidation preferences, participation rights and the payout waterfall — this is an ownership model, not an exit model.
- Convertible notes with interest or a maturity date.
- Anti-dilution ratchets, MFN clauses and pro-rata side letters.
- Multiple share classes, warrants, secondary sales and vesting schedules.
- Whether a given investor would actually accept these terms.
Questions founders ask
What is the difference between a pre-money and a post-money SAFE?
A post-money SAFE fixes the holder at amount divided by cap of the company as it stands after every SAFE converts and before the new money lands. Post-money SAFEs therefore do not dilute each other — they dilute the founders. A pre-money SAFE is priced off a cap table that excludes all SAFEs, so every extra SAFE lowers what each SAFE holder ends up owning. Identical money on an identical cap can produce clearly different ownership depending on which paper was signed.
Does the valuation cap or the discount apply when a SAFE converts?
Whichever produces the lower price per share for the investor, because a lower price buys more shares for the same money. This calculator works out both prices and labels which one won for each SAFE, so you can see how close the two were and what would flip the result.
How does an option pool refresh change the dilution?
A pool top-up agreed as part of the round is normally created out of the pre-money, so existing shareholders pay for it rather than the incoming investors. It also dilutes post-money SAFE holders here, because the standard post-money SAFE excludes that increase from the capitalisation it measures itself against. Pre-money SAFE holders are left where they were: the increase sits inside their conversion base, so their price per share falls by exactly enough to cancel the effect.
What happens to a SAFE with no cap and no discount?
It is modelled as converting at the priced-round share price — the same terms as the new money — and the result flags that this is what happened. That is the only reading that does not invent a number you never entered.
Does my cap table get sent anywhere?
No. The calculator is JavaScript running inside your own browser tab. Nothing you type is transmitted to SendVC or to anyone else, nothing is written to a database, and nothing is saved on your device — reloading the page clears every field.
Is this legal, tax or financial advice?
No. It is an estimate built from the numbers you typed, using the standard reading of the Y Combinator SAFE instruments. A real conversion follows the exact wording of the documents you signed and of your charter. Have your lawyer confirm the numbers before you sign, countersign or send a term sheet.
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