What is Fully Diluted Shares?
Short answer: Fully diluted shares are the shares outstanding plus the additional shares assumed to arise from specified options, warrants, convertible securities and equity reserves. The measure is a modelling convention, not a single universal legal or accounting number. A term sheet, cap table, earnings-per-share calculation and acquisition agreement may each use a different definition for a different purpose.
The starting point is issued and outstanding shares by class. Potential additions can include granted options, restricted share units, warrants, convertible notes, SAFEs and an unallocated option pool. Some calculations use the treasury-stock method for in-the-money options, while private financing cap tables often count the full underlying shares. Instruments with caps, discounts or variable conversion formulas need scenario-specific share counts. Authorised but unissued shares are not automatically included. Preference rights and voting differences also remain important even when all securities are shown on an as-converted basis.
How it works
Write the convention at the top of the model. Reconcile issued shares to the statutory register. Add each award and instrument once, using the correct conversion price and measurement date. Separate granted awards from the remaining pool. Identify cancelled, expired and out-of-the-money instruments rather than netting them silently. For a financing price, divide pre-money valuation by the contractually agreed pre-money fully diluted denominator. For holder ownership, divide the holder's shares on the same basis by the total. Add columns for issued, as-converted and financing-definition totals so users do not substitute one for another.
Fully diluted ownership = holder shares on the stated diluted basis / total fully diluted shares on the same basis
Example
A company has 5,000,000 ordinary shares and 1,000,000 preferred shares outstanding. Employees hold 300,000 granted options, and 200,000 shares remain in the pool. A note would convert into 250,000 shares at the modelled round price, and warrants cover 100,000 shares. Under a convention that includes all those items at gross underlying share count, fully diluted shares are 6,850,000. A founder with 3,000,000 ordinary shares owns 50% of the 6,000,000 issued shares but 43.80% on this fully diluted basis. If the term sheet excludes the unallocated pool, its denominator is 6,650,000 and the percentage is 45.11%.
Why it matters
The denominator drives financing price per share, reported ownership, option-pool planning and acquisition proceeds models. Investors use it to confirm the stake they are buying and the overhang from existing instruments. Founders use it to see dilution before accepting a term sheet. Buyers use a security-by-security schedule to determine what must be acquired, cancelled or paid out. A clean cap table should therefore preserve source documents and show alternative definitions, especially when a headline percentage will be communicated to the board or used in definitive agreements.
Fully diluted does not mean that every instrument will legally convert or receive value. Conditions, vesting, performance targets, exercise prices, caps and expiration dates matter. The accounting calculation for diluted earnings per share can exclude antidilutive instruments and apply prescribed methods that differ from transaction modelling. Tax and company-law treatment also varies. Do not infer liquidation proceeds from a fully diluted percentage where preference classes exist. Before closing, counsel, finance and the cap-table administrator should reconcile the stated convention to charter documents, award plans, board approvals, side letters and every outstanding security.