Equity Dilution Calculator

When new shares are issued, the total share count grows, so the same shares you hold now represent a smaller slice — your stake scales by existing ÷ (existing + new). That is cap-table dilution.

Your numbers

Current stake(%)Existing shares()New shares issued()

Stake after dilution

Dilution

What it means

After the new round your stake drops from 10% to 8% (−2 points).

Formula

Stake after dilution = Current stake × Existing shares ÷ (Existing shares + New shares issued)

Real rounds can be more complex with preferred-stock conversion or option-pool top-ups. This assumes a simple common-stock cap table.

What to enter

Input	Default	Accepted range
Current stake (%)Your ownership percentage before the new round.	10	0 ~ 100
Existing sharesTotal shares outstanding before the new issuance.	1,000,000	1 and up
New shares issuedShares newly issued in this round.	250,000	0 and up

Step by step

FormulaStake after dilution = Current stake × Existing shares ÷ (Existing shares + New shares issued)

With the default numbersStake after dilution = 10 × 1,000,000 ÷ (1,000,000 + 250,000)

AnswerStake after dilution = 8 %

Quick reference table

Results when only Current stake (%) changes and everything else stays put.

Current stake (%)	Stake after dilution (%)	Dilution (%)
5	4	1
7.5	6	1.5
10	8	2
15	12	3
20	16	4

What each result means

Result	At default values
Stake after dilution (%)The percentage your unchanged holding represents after the new shares exist.	8
Dilution (%)How many percentage points the stake fell by.	2

Common mistakes

Real rounds can be more complex with preferred-stock conversion or option-pool top-ups. This assumes a simple common-stock cap table.

Glossary

Current stake: Your ownership percentage before the new round.
Existing shares: Total shares outstanding before the new issuance.
New shares issued: Shares newly issued in this round.
Stake after dilution: The percentage your unchanged holding represents after the new shares exist.
Dilution: How many percentage points the stake fell by.

Frequently asked questions

QHow is Equity Dilution Calculator calculated?

Stake after dilution = Current stake × Existing shares ÷ (Existing shares + New shares issued) — When new shares are issued, the total share count grows, so the same shares you hold now represent a smaller slice — your stake scales by existing ÷ (existing + new). That is cap-table dilution.

QCan you walk through an example?

With Current stake 10%, Existing shares 1,000,000, New shares issued 250,000, the answer is Stake after dilution 8%.

QWhat do I need to enter?

Enter Current stake, Existing shares, New shares issued. The result recalculates as you type, and an empty box counts as zero.

QHow much does the answer move if I change a number?

Changing only Current stake (%) moves the answer to Current stake (%) 5 → Stake after dilution (%) 4 and Current stake (%) 20 → Stake after dilution (%) 16. The table below lays out five steps.

QHow are the numbers rounded?

Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.

QAnything to watch out for?

Real rounds can be more complex with preferred-stock conversion or option-pool top-ups. This assumes a simple common-stock cap table.

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Tax rates and interest conventions differ by country and product — check your contract for real transactions.