How much does a founder get diluted by a seed round?

By the round's share of the post-money valuation, plus whatever the option pool takes. Raising 2 million on an 8 million pre-money sells 20% of the company. Add a 10% pool out of the pre-money and the founders are at 70%, not 80%, while the investor still holds exactly 20%.

What is the difference between a pre-money and a post-money SAFE?

Who absorbs the dilution when several SAFEs convert. A post-money SAFE fixes the holder's percentage against the table after every SAFE has converted, so other SAFEs dilute the founders instead. Pre-money SAFEs dilute each other. On the same cap and amount, post-money always costs the founders more.

How does a SAFE convert at a priced round?

At the better of its valuation cap and its discount, measured in shares. The cap route prices the money against the cap; the discount route prices it at a percentage off what the new investor pays. The holder takes whichever gives more shares. An uncapped SAFE only has the discount.

Who pays for the option pool increase in a round?

Whoever the term sheet says. A pre-money pool sits inside the pre-money valuation, so the existing holders fund it and the new investor's percentage is unchanged. A post-money pool dilutes everyone including the money that has just come in. The gap is usually several points of founder ownership.

Does this calculator model liquidation preferences?

No. It models ownership only. Preferences, participation, anti-dilution ratchets and pro-rata rights do not move a percentage on the cap table, but they decide who gets paid what at an exit, and a 1x participating preference can matter far more than a couple of points of ownership.

Is anything I type here sent anywhere?

No. The whole calculation runs in your browser. There is no account, no backend and no analytics on the numbers themselves. Nothing is uploaded, and nothing is stored between visits, so closing the tab loses the model. Copy the figures out if you want to keep them.

Equity calculator

Model what SAFEs, priced rounds and option pool increases do to your cap table. Add the events in the order they happen and see every stakeholder's ownership before and after, how much dilution the founders take, and what changes when a pool comes out of the pre-money instead of the post.

1. Where you are today

Enter the cap table as it stands, on a fully diluted basis. Use one currency throughout. Only the ratios move the answer, so the choice of currency never changes a percentage.

Current valuation (409A or last post-money)

Stakeholder

Type

2. What happens next

Add the events in the order they happen. SAFEs sit outstanding until the next priced round and convert into it. A pre-money pool increase is folded into the next priced round, so the existing holders pay for it; a post-money one applies where it sits and dilutes everyone on the table at that point, including money that has just come in.

No events yet. Add a SAFE, a priced round or a pool increase to see what it does to the table.

3. The cap table after all of it

Stakeholder	Type	Shares	Before	After	Change
Founder	Founder	1,000,000	100.00%	100.00%	+0.00 pp
Fully diluted total		1,000,000	100.00%	100.00%

Founders go from 100.00% to 100.00%, 0.00 percentage points of dilution across 0 events.

Shares at the start: 1,000,000
Shares at the end: 1,000,000
Price per share today: 8
Price per share, last priced round: —

What these numbers assume

Everything is fully diluted and one class of share. Authorised but unissued shares, warrants, restricted stock and the difference between common and preferred are all ignored.
A SAFE takes the better of its cap and its discount, measured in shares: whichever route gives the holder more shares is the one used.
Post-money SAFE means post the SAFE money. The holder’s percentage is fixed against the table once every SAFE has converted and the pool has been topped up, but before the new round’s money, so other SAFEs dilute the founders rather than the SAFE holder. A pre-money SAFE converts against a table that excludes the converting SAFEs, so pre-money SAFEs do dilute each other.
A pre-money pool increase sits inside the next priced round’s pre-money valuation, which is why the new investor’s percentage does not move when you change it. A post-money increase dilutes everyone on the table where it sits. With no round in between, the two are the same thing.
Liquidation preferences, participation rights, anti-dilution ratchets, pro-rata rights and interest on convertible notes are not modelled. For a note, enter the principal plus accrued interest as the amount. None of these change ownership percentages, but all of them change who gets paid what at an exit.
Share counts are rounded to whole shares for display and percentages to two decimal places, so a column can read a hundredth of a point away from 100%.
This is planning, not legal, tax or investment advice. Before you sign anything, have the actual documents modelled by your lawyer and your accountant. The terms in a real SAFE or share purchase agreement can differ from the conventions used here.
Nothing you type leaves your browser. The whole calculation runs on this page and nothing is sent anywhere or stored.

How the model works

Everything runs off share counts, not percentages, which is the only way a stack of SAFEs and a pool increase come out right. Each event is applied in order. A SAFE does nothing on its own: it sits outstanding until a priced round, then converts alongside every other outstanding SAFE. A priced round issues shares at the pre-money valuation divided by the fully diluted count at that moment, so the new investor ends up with the round amount over the post-money valuation.

The pool, the SAFE conversion and the round price all depend on each other. A bigger pool means more shares, which means a lower price per share, which means the round buys more shares, so the page solves them together rather than in one pass. That is the part most spreadsheets get subtly wrong.

Four things worth checking before you sign

The pool shuffle is where founders lose points quietly

A term sheet that reads 'a 10% option pool will be in place at closing' almost always means pre-money, which is the existing holders paying for the next two years of hiring out of their own stake. The investor's percentage is identical either way, which is why it is easy to skim past.

Stacked SAFEs are worse than they look

Each post-money SAFE takes a fixed slice of the table after all SAFEs convert, so a fourth SAFE does not dilute the first three. It dilutes the founders. Four 1 million SAFEs on a 10 million cap is 40% gone before a priced round has happened, not something in the twenties.

A low cap and a big discount are not the same lever

The cap only binds when the round prices above it; the discount only binds when the round prices below the cap-implied valuation. Which one wins depends on a number you do not know yet. Model both ends of the range you think the next round lands in.

Ownership is not the same as proceeds

This page stops at percentages. Preference stacks, participation and seniority decide the split at an exit, and in a modest outcome they can leave common holders with a fraction of what the percentage suggests. Model the waterfall separately before you treat a percentage as money.

How to use it

Enter today’s cap table on a fully diluted basis, including any option pool already in place as its own row.
Add the events in the order they will happen. Order matters: the same pool increase before and after a round gives different answers.
Run the round twice, once at the valuation you hope for and once at the one you would accept, and look at the founder line in both.
Take the result to your lawyer and your accountant against the actual documents. The conventions here are standard, but the terms you sign are what count.

Built in-house by Plaitr from the standard conventions for SAFE conversion and option pool sizing: a SAFE converts at whichever of its cap and its discount gives the holder more shares, a post-money SAFE is measured against the table after all SAFEs convert but before the new money, and a pre-money pool sits inside the pre-money valuation. Real documents vary, and this is planning, not legal, tax or investment advice. Nothing you type leaves your browser: the whole calculation runs locally and nothing is stored.

Questions

How much does a founder get diluted by a seed round?: By the round's share of the post-money valuation, plus whatever the option pool takes. Raising 2 million on an 8 million pre-money sells 20% of the company. Add a 10% pool out of the pre-money and the founders are at 70%, not 80%, while the investor still holds exactly 20%.
What is the difference between a pre-money and a post-money SAFE?: Who absorbs the dilution when several SAFEs convert. A post-money SAFE fixes the holder's percentage against the table after every SAFE has converted, so other SAFEs dilute the founders instead. Pre-money SAFEs dilute each other. On the same cap and amount, post-money always costs the founders more.
How does a SAFE convert at a priced round?: At the better of its valuation cap and its discount, measured in shares. The cap route prices the money against the cap; the discount route prices it at a percentage off what the new investor pays. The holder takes whichever gives more shares. An uncapped SAFE only has the discount.
Who pays for the option pool increase in a round?: Whoever the term sheet says. A pre-money pool sits inside the pre-money valuation, so the existing holders fund it and the new investor's percentage is unchanged. A post-money pool dilutes everyone including the money that has just come in. The gap is usually several points of founder ownership.
Does this calculator model liquidation preferences?: No. It models ownership only. Preferences, participation, anti-dilution ratchets and pro-rata rights do not move a percentage on the cap table, but they decide who gets paid what at an exit, and a 1x participating preference can matter far more than a couple of points of ownership.
Is anything I type here sent anywhere?: No. The whole calculation runs in your browser. There is no account, no backend and no analytics on the numbers themselves. Nothing is uploaded, and nothing is stored between visits, so closing the tab loses the model. Copy the figures out if you want to keep them.

Run the payment, not just the maths

Plaitr runs bank rails and stablecoin rails from one account, so you can pick whichever is cheaper per payment and keep the books reconciled either way.

See the product →