Cap Table: What It Is and Why Every Founder Needs One

In this article: what a cap table is, what it should include, how dilution works, and the common mistakes founders make.

If you are building a startup, understanding your cap table is one of the most important things you can do.

A cap table — short for capitalisation table — is a record of who owns what shares in your company. It is also one of the key tools for managing your startup effectively and demonstrating credibility to investors.

What is a cap table?
A cap table is a document — usually a spreadsheet — that sets out the equity ownership structure of a company. It lists:

– every shareholder in the company
– the number and type of shares they hold
– the percentage of the company those shares represent — typically shown in two ways:
– fully diluted share capital % — ownership of all shares including the unallocated option pool, warrants, and other convertible instruments, as if everything had already been exercised
– issued share capital % — ownership of all shares that have actually been issued to shareholders

Why every founder needs a cap table
A well-maintained cap table does several important jobs.

Ownership clarity
It sets out exactly who owns what, so there are no surprises or disputes — particularly important as the company grows and more shareholders come on board.

Investor confidence
Investors and their legal advisers will ask to see your cap table early in any fundraising conversation. An accurate, up-to-date cap table shows you know what you are doing. An incomplete or inconsistent one raises immediate red flags.

Fundraising planning
One of the key purposes of a cap table is understanding the dilution effect of raising investment — that is, what happens to existing shareholders’ percentage ownership when new shares are issued. Being able to explain this clearly to investors is essential.

Think of your company’s equity as a pie. Each shareholder owns a slice. When you raise investment by issuing new shares, the pie gets divided into more slices — so each existing shareholder’s slice becomes proportionally smaller. That reduction is dilution.

A simple example: you own 50 shares out of 100 total, giving you 50% of the company. You then issue 30 new shares to investors, bringing the total to 130. Your 50 shares now represent 38.46% — a reduction of just over 11 percentage points. That is dilution.

A current cap table is the tool that lets you model this properly before agreeing to any investment terms.

Exit planning
When you come to sell the business, your cap table determines how proceeds are distributed among shareholders. Errors at this stage can have serious financial consequences for everyone involved.

What to include in a cap table
A basic cap table for a startup should include:

– the names of all shareholders — founders, investors, and any other equity holders
– the class and number of shares held by each shareholder, such as ordinary shares or preference shares
– the percentage ownership — split into issued share capital and fully diluted share capital
– the price paid per share and the total amount invested in each round
– any options, warrants, or convertible instruments not yet converted into shares — these are included in your fully diluted figure but not your issued share capital figure

Common cap table mistakes to avoid

Rounding errors
You cannot issue fractions of a share — shares must be whole numbers. This catches founders out more often than you might expect.

Say an investor is putting in £125,000 at a price of £7.43 per share. Dividing £125,000 by £7.43 gives you 16,823.69 shares. You cannot issue 0.69 of a share, so you need to round. The rule is always round down — never up.

In Excel, use: ROUNDDOWN((125000/7.43),0) = 16,823 shares

Rounding up to 16,824 would mean the investor has not fully paid for their shares — they would still legally owe the company money, because all shares must be fully paid on issue.

Leaving it too late
It is easy to think a cap table is something you can deal with later, when the company is more complex. But complexity is exactly what makes it harder to reconstruct. Starting with just two founders is the easiest moment to build good habits. Once you add angel investors, a VC, and an employee option pool, untangling an incomplete cap table is time-consuming and expensive.

Ignoring convertible instruments
CLNs (Convertible Loan Notes), SAFEs (Simple Agreements for Future Equity), and ASAs (Advance Subscription Agreements) are common early-stage funding tools. The money comes in now and converts into shares later — usually at the next priced round, often at a discount or subject to a valuation cap.

Just because they have not yet converted does not mean they should be left off the cap table. They need to appear in your fully diluted view so you are not surprised by the dilution effect when conversion happens.

How to set up and maintain your cap table

Start early
Create your cap table as soon as the company is incorporated, even if it only shows the founding team. It is much easier to build good habits early than to piece the picture together later.

Record every transaction
Every time shares are issued, transferred, or cancelled, update your cap table promptly. Do not let it fall behind events.

Always maintain the fully diluted view
Keep a fully diluted column showing ownership on the assumption that all options and convertible instruments are exercised. This is what investors will focus on.

Keep it consistent with your statutory records
Your cap table must match your Companies House filings and your shareholder register. Inconsistencies between these documents are an immediate red flag for investors and their lawyers.

How Buckworths can help
Advising on investment rounds and helping founders set up and maintain accurate cap tables is central to what we do. If you are preparing to raise investment, structuring a new round, or simply want to make sure your cap table is in good shape, get in touch.

Get in touch with our experts by reaching out to us at [email protected] or 020 7952 1723.