How It Works
This calculator works in 4 steps.
Enter common shares
Type issued common stock.
Add each instrument
Add preferred series, options, warrants, RSUs, and convertibles as rows.
Set ratios and inclusion
Type each conversion ratio and mark whether the row counts, per the governing definition.
Read the total
The calculator returns the fully diluted count and each holder group's percentage.
The Formula
The formula sums common shares and every included instrument multiplied by its conversion ratio.
FD = S_common + Σ (Nᵢ × rᵢ) for included instruments% = 100 × (group shares) / FD- S_common:
- Issued common shares
- Nᵢ:
- Units of instrument i
- rᵢ:
- Shares per unit of instrument i
8,000,000 common, 2,000,000 preferred at 1:1, 2,000,000 granted and reserved options, 150,000 warrants, and 100,000 RSUs total 12,250,000 fully diluted shares.
Conversion Table
The conversion table totals a 6-line sample capitalization.
| Instrument | Units | Shares counted |
|---|---|---|
| Common stock (issued) | 8,000,000 | 8,000,000 |
| Preferred stock (as converted, 1:1) | 2,000,000 | 2,000,000 |
| Options granted | 1,200,000 | 1,200,000 |
| Options reserved, unallocated | 800,000 | 800,000 |
| Warrants | 150,000 | 150,000 |
| RSUs unvested | 100,000 | 100,000 |
| Total fully diluted | — | 12,250,000 |
What Is the Fully Diluted Share Count Calculator?
The Fully Diluted Share Count Calculator is a tool that adds up all shares now held plus every item you list that can turn into shares. That includes preferred stock, options, warrants and RSUs. The user chooses which instruments to include; definitions vary by document.
Startup term sheets often count the unused option pool. Public firms follow other rules. Each item gets its own line and ratio. That way the total matches the terms in your deal papers.
Common Uses
There are 5 main uses of this calculator.
Round pricing
Founders set price per share from fully diluted shares.
Ownership reporting
Companies report fully diluted ownership to investors.
Option grant sizing
HR teams express grants as a percent of fully diluted shares.
M&A analysis
Acquirers compute per-share deal value.
Valuation inputs
Firms that set 409A values need this share data.