Option pool (ESOP) calculator

An employee share option plan sets aside shares for staff, usually as an option pool. Investors often ask for the pool to be topped up before they invest, inside the pre-money.

The formula

Option pool = pool wanted × shares after the round − pool you have

Worked example: 142,857 new pool shares

The example uses the guide's seed round, £200,000 for 20%, with a matching cap table, exit, fund and market.

A 10% pool after the round needs 142,857 new shares
At £0.70 a share, that is £100,000 of the pre-money

Try it with your numbers

Work out your option pool

It starts on the example. Replace any figure with your own; nothing you type leaves your browser.

Your deal numbers

Start with any one figure. Each one you add works out more below. Your numbers are kept in this browser only.

What this calculation uses

Pre-money valuation (needed)

You can type 2m or 750k.

New investment (needed)

Shares in issue (needed)

Options already granted

Unallocated option pool

In shares. 0 if you have none.

Option pool wanted after the round (needed)

Add more of your numbers

Open a group to fill it in. Everything you add shows up in the list below the calculator.

An investment offer

Investment offered

For this share of the company

Your round

Your own shares

Money converting at the round

Amount converting

From an ASA, SAFE or loan note.

Valuation cap

Leave blank for no cap.

Discount

Interest a year (loan notes)

Months since the note was issued

A sale of the company

Sale price of the company

What the preferred investor put in

What the preferred investor owns

1x2x

Participating preference

What the founders own

An investor's return

Amount invested

Share bought

Later dilution

30 means later rounds shrink that share by 30%.

Sale price at the exit

Years to the exit

The next round

Share you own now

Size of the next round

Its pre-money valuation

Last round's post-money

New round's pre-money

A venture fund

Fund size (committed)

Paid in by investors so far

Invested in companies so far

Paid back to investors

Value of what the fund still holds

Your market

Potential customers

What one pays a year

Share you can serve

Share of those you could win

A SEIS, EIS or VCT investment

Amount an investor puts in

Shares that vest

Shares or options granted

Vesting period

Cliff

Months worked so far

Your option pool

142,857

new pool shares

A 10% pool after the round needs 142,857 new shares
At £0.70 a share, that is £100,000 of the pre-money

Formula: Pool wanted × shares after the round − pool you have.

Effective pre-money: £700,000; what existing shareholders really get

How to read your result

The effective pre-money is what existing shareholders really get once the pool is paid for. Size the pool to your hiring plan rather than a round number.

Watch out for

The pool size and the scheme are separate decisions. In the UK, EMI options can be tax-advantaged for employees.

Last checked 24 October 2026. Estimates only, not financial, tax or legal advice: check your accounts and documents, and take advice before you act. More terms in the startup glossary.