This dilution calculator shows what your round really means for your cap table. Enter your round size and pre-money valuation, add your shareholders, option pool and any ASAs or SAFEs, and see your post-money valuation, how much equity you're selling and how everyone's ownership changes. You can download the whole thing as a CSV.
1The round
2Current shareholders
Everyone who holds shares today and how many each holds. Only know percentages? Enter them as shares out of 100.
| Name | Shares | Remove |
|---|---|---|
3Option pool
4ASAs and SAFEs converting in this round
Each one converts at whichever gives the holder more shares: the round price less the discount, or the valuation cap. Leave the cap blank if there isn't one. Remove the example if you don't have any.
5New investors in this round (optional)
Name who's putting money in. Anything left of the round size shows as "Other new investors".
| Name | Amount (£) | Remove |
|---|---|---|
6Results
Cap table before and after the round
| Name | Type | Price per share | Shares before | % before | Shares after | % after | Value after |
|---|---|---|---|---|---|---|---|
| Founder 1 | Shareholder | – | 5,000 | 50.00% | 5,000 | 32.50% | £812,500 |
| Founder 2 | Shareholder | – | 4,000 | 40.00% | 4,000 | 26.00% | £650,000 |
| Angel investor | Shareholder | – | 1,000 | 10.00% | 1,000 | 6.50% | £162,500 |
| ASA investor | ASA / SAFE (discount) | £130.00 | – | – | 769 | 5.00% | £125,000 |
| Lead investor | New money £300,000 | £162.50 | – | – | 1,846 | 12.00% | £300,000 |
| Other new investors | New money £200,000 | £162.50 | – | – | 1,231 | 8.00% | £200,000 |
| Issued shares | 10,000 | 100.00% | 13,846 | 90.00% | £2,250,000 | ||
| Option pool | Options (+1,538 new) | – | 0 | 0.00% | 1,538 | 10.00% | £250,000 |
| Fully diluted total | 10,000 | 100.00% | 15,385 | 100.00% | £2,500,000 |
New investors pay £162.50 per share: the £2,000,000 pre-money valuation divided by 12,308 shares before the new money (existing shares, the new option pool and ASA conversions).
- ASA investor: round price £162.50 less 20% = £130.00, and pre-money cap £2,500,000 ÷ 11,538 shares = £216.67. The discount gives the lower price, so it converts at £130.00: £100,000 ÷ £130.00 = 769 shares, worth £125,000 at the round price.
How to use the calculator.
- The round: how much new money you're raising and the pre-money valuation you've agreed or are aiming for. You can type amounts like 500k or 1.5m.
- Current shareholders: everyone who holds shares today. Shares give the most accurate answer, but percentages out of 100 work too.
- Option pool: any existing pool, and the size investors want it to be after the round.
- ASAs and SAFEs: anything converting in this round, with its discount and valuation cap.
- New investors: optional. Name who's investing to see each of them in the cap table.
The results and cap table update as you type. Use Download as CSV to save your inputs and the before and after cap table, ready to open in Excel or Google Sheets.
How the calculations work.
- Post-money valuation is the pre-money valuation plus the new money raised.
- Price per share is the pre-money valuation divided by the fully diluted shares before the new money. That includes the option pool and any ASAs or SAFEs converting in the round.
- New shares issued are the new money divided by the price per share.
- Equity sold is the new investors' shares as a share of the total after the round.
Existing shareholders keep the same number of shares, but because new shares are created, each of them owns a smaller percentage. That's dilution. With no option pool or ASAs, raising £500,000 at a £2,000,000 pre-money valuation means a £2,500,000 post-money valuation and 20% sold to new investors.
Option pools and the "effective" pre-money.
Investors usually ask for an option pool so you can hire, and they usually want it created before the round, inside the pre-money valuation. That means the new options dilute existing shareholders only, not the new investors.
The same is true of ASAs and SAFEs converting in the round. So the headline pre-money valuation and the value of the shares existing shareholders actually hold can be quite different. The calculator shows this as the effective pre-money for existing shareholders. It's worth knowing before you agree a valuation.
ASAs and SAFEs.
An Advance Subscription Agreement (ASA) is the UK's most common way to take investment before a priced round. The investor pays now and receives shares when the next round happens, usually at a discount to the round price, sometimes with a valuation cap. SAFEs are the US equivalent and work in a similar way. UK founders raising from SEIS or EIS investors generally use ASAs, because SAFEs aren't designed for those schemes. Our guide to advance subscription agreements covers the terms and HMRC rules in full.
- Discount: the holder converts at the round price less the discount, for example 20% off.
- Valuation cap: the holder converts as if the valuation were no higher than the cap.
- Both: the holder gets whichever gives them more shares. The calculator shows which one applied.
- Pre-money or post-money cap: a pre-money cap is divided by the shares before the round. A post-money cap, as used in Y Combinator's SAFE, fixes the holder's percentage of the company before the new money comes in, so it's more dilutive for founders.
ASAs also have a longstop date. If there's no priced round by then, the ASA converts anyway at a pre-agreed backstop valuation. In the UK the longstop is usually six months after the ASA is signed, which keeps it within HMRC's rules for SEIS and EIS. SAFEs can run for much longer, and often have no fixed conversion date at all.
This calculator models conversion in a priced round. If your ASA is converting at its longstop instead, the backstop valuation sets the price, so check the terms of your agreement.
Exactly how a cap is applied can vary from one agreement to another, so check the wording in yours.
How much equity should you give away at pre-seed?.
At pre-seed, you can typically expect to give away somewhere between 10% and 20% of the company, and sometimes up to 25%. Where you land depends on how much you need to raise, your traction and how competitive the round is. For the data behind these ranges and how dilution builds up to Series A, read our guide to how much equity to give away at pre-seed.
If you're raising from SEIS or EIS investors (see our SEIS and EIS guide), also keep an eye on individual holdings. An investor generally can't hold more than 30% of the company, including their associates, and still claim the tax relief.
What this doesn't include.
The calculator models a straightforward priced round. It doesn't cover different share classes, liquidation preferences, warrants, interest on convertible loan notes or anti-dilution rights. Any of these can change the numbers, so check your actual cap table with your lawyer or accountant before you agree terms.
Getting your round ready? Our guides to pre-seed funding, pre-money vs post-money valuation, cap tables, the fundraising data room and getting warm introductions are a good next step.
Questions founders ask.
Pre-money valuation is what the company is valued at before the new investment. Post-money valuation is the pre-money valuation plus the new money raised.
Divide the new investors' shares by the total shares after the round. With no option pool or ASAs, that's simply the amount raised divided by the post-money valuation: £500,000 raised at a £2,000,000 pre-money valuation is £500,000 ÷ £2,500,000, or 20%.
Typically between 10% and 20%, and sometimes up to 25%, depending on how much you need to raise, your traction and how competitive the round is.
At the next priced round, the ASA converts into shares at the round price less any discount, or at the valuation cap if that gives the investor more shares. If there's no priced round by the longstop date, usually six months after signing in the UK, it converts at a pre-agreed backstop valuation instead. SAFEs can run for longer and often have no fixed conversion date.
Usually, yes. Investors normally ask for the pool to be created before the round, which means it dilutes existing shareholders but not the new investors.