Cap table & dilution calculator
Model your round in seconds: see founder ownership after, who really pays for the option pool, the SEIS/EIS split and investor relief, and where your stake lands at Series A.
The standard play: SEIS for the first £250k, EIS for the rest. SEIS shares must be issued first.
Questions founders ask
How does the option pool shuffle dilute founders?+
When the option pool is created or topped up before the round prices (pre-money), it dilutes only the existing shareholders — the founders — not the incoming investor. A larger pre-money pool quietly transfers 8–12% of founder equity, which is why investors often push for a bigger pool. Switch the calculator to a post-money pool to see the difference.
How do I split a round between SEIS and EIS?+
A company can raise up to £250,000 in total under SEIS, which gives investors 50% income-tax relief. The standard structure is to allocate the first £250,000 of your round to SEIS, then EIS (30% relief) for the rest. SEIS shares must be issued before EIS shares. The calculator does this split for you and shows the relief.
What are the per-investor SEIS and EIS limits?+
An individual investor can put up to £200,000 per tax year into SEIS and up to £1m per tax year into EIS (£2m if at least £1m goes into knowledge-intensive companies). These are per-investor limits, separate from the company's SEIS £250,000 lifetime cap.
How much do founders typically get diluted?+
A UK seed round typically dilutes founders 15–25%, and a Series A another 20–30%. Use the Series A projection to see where your ownership lands after the next round.
Is this a substitute for a real cap table?+
No. It's a fast way to model dilution and the SEIS/EIS split before you negotiate. For your legal cap table and share issues, keep a proper register that matches what's on the public record.