Important Note : This calculator estimates simple equity-valuation math for a priced round. It does not model option pools, SAFEs, convertible notes, liquidation preferences, anti-dilution rights, debt, taxes, legal terms, or fully diluted cap table effects.

Use this Pre & Post-Money Valuation Calculator to estimate startup valuation, investor equity, investment amount, and founder ownership after a funding round. Enter any two values, such as investment amount and investor ownership, and the calculator solves the related pre-money and post-money valuation math.

Reviewed by: AjaxCalculators Editorial Team
Last updated: April 26, 2026
Method source: Standard startup financing relationships using post-money valuation, pre-money valuation, investment amount, and investor ownership percentage
Editorial standards: AjaxCalculators Editorial Policy

What This Pre & Post-Money Valuation Calculator Calculates

This calculator estimates:

• Pre-money valuation
• Post-money valuation
• Investment amount
• Investor’s equity percentage
• Founder ownership after the round
• Step-by-step valuation derivation
• Sanity check for the calculated values

The live tool lets you enter any two of the following values: investment, investor’s equity, pre-money valuation, or post-money valuation. The other two values update from the core startup-financing formulas.

What Pre-Money and Post-Money Valuation Mean

Pre-money valuation is the estimated equity value of a company before a new investment round is added.

Post-money valuation is the estimated equity value of the company after the new investment is included.

For example, if a startup has a pre-money valuation of $4 million and raises $1 million, the post-money valuation is $5 million.

How the Pre & Post-Money Valuation Calculator Works

1) Post-Money Valuation Formula

The core relationship is:

Post-money valuation = Pre-money valuation + Investment

This means the new cash investment is added to the company’s pre-money equity valuation to estimate the post-money valuation.

2) Investor Equity Formula

Investor ownership is based on the investment amount divided by the post-money valuation.

Investor equity = Investment ÷ Post-money valuation

To display the result as a percentage:

Investor equity % = Investment ÷ Post-money valuation × 100

3) Founder Ownership After the Round

In a simple round with no other dilution effects, founder ownership after the round can be estimated as:

Founder ownership = 100% − Investor equity %

For example, if the investor receives 20% of the company after the round, the remaining post-money ownership is 80% before considering other shareholders, option pools, or additional securities.

4) Solve Post-Money From Investment and Equity

If you know how much an investor is investing and what ownership percentage they will receive, you can solve post-money valuation as:

Post-money valuation = Investment ÷ Investor equity

For example, if an investor puts in $1 million for 20%, the implied post-money valuation is:

$1,000,000 ÷ 0.20 = $5,000,000

5) Solve Pre-Money From Post-Money and Investment

If post-money valuation and investment are known, pre-money valuation is:

Pre-money valuation = Post-money valuation − Investment

6) Solve Investment From Pre-Money and Investor Equity

If pre-money valuation and investor equity are known, the required investment can be solved by rearranging the ownership formula:

Investment = Investor equity × Pre-money valuation ÷ (1 − Investor equity)

This formula treats investor equity as a decimal. For example, 20% should be entered as 0.20 in the formula.

Why Pre-Money vs Post-Money Matters

Pre-money and post-money valuation are important because they affect how much ownership the investor receives and how much ownership existing shareholders keep.

A $1 million investment at a $5 million post-money valuation gives the investor 20% ownership. But a $1 million investment at a $5 million pre-money valuation gives a $6 million post-money valuation, so the investor receives about 16.67% ownership.

This is why founders and investors should be clear about whether a valuation is being discussed on a pre-money or post-money basis.

Assumptions and Important Notes

• This calculator uses simple priced-round equity valuation math.
• It assumes the investment is new cash added to the company.
• It assumes investor equity is based on investment divided by post-money valuation.
• It treats pre-money and post-money values as equity valuation, not enterprise value.
• It does not model option pool expansion, employee stock option plans, warrants, convertible notes, SAFEs, valuation caps, discounts, liquidation preferences, anti-dilution provisions, debt, or multiple share classes.
• It does not create a full cap table.
• It does not determine whether a startup valuation is fair, realistic, or investable.
• Actual fundraising terms should be reviewed with qualified legal, tax, accounting, or startup-finance professionals.

Worked Example

Suppose a startup has a $4,000,000 pre-money valuation and raises a $1,000,000 investment.

Step 1: Calculate post-money valuation
Post-money valuation = 4,000,000 + 1,000,000 = $5,000,000

Step 2: Calculate investor equity
Investor equity = 1,000,000 ÷ 5,000,000 = 0.20

Step 3: Convert to percentage
0.20 × 100 = 20%

Step 4: Estimate founder ownership after the round
Founder ownership = 100% − 20% = 80%

So, after a $1 million investment at a $4 million pre-money valuation, the company has a $5 million post-money valuation, the investor owns 20%, and the remaining post-money ownership is 80% before any other cap table effects.

Worked Example: Find Valuation From Investment and Equity

Suppose an investor offers $500,000 for 10% of a startup.

Step 1: Convert equity to decimal
10% = 0.10

Step 2: Calculate post-money valuation
Post-money valuation = 500,000 ÷ 0.10 = $5,000,000

Step 3: Calculate pre-money valuation
Pre-money valuation = 5,000,000 − 500,000 = $4,500,000

This means a $500,000 investment for 10% implies a $5 million post-money valuation and a $4.5 million pre-money valuation.

How to Use This Pre & Post-Money Valuation Calculator

1. Select the currency symbol you want to display.
2. Choose the amount scale, such as units, thousands, millions, or billions.
3. Enter any two known values: investment, investor equity, pre-money valuation, or post-money valuation.
4. Let the calculator solve the remaining two values.
5. Review the quick summary, founder ownership estimate, sanity check, and step-by-step derivation.
6. Use the PDF download option if you want to save the result summary.

How to Interpret the Result

Investment is the new money added during the financing round.

Investor’s equity is the ownership percentage the investor receives after the round.

Pre-money valuation is the company’s estimated value before the new investment.

Post-money valuation is the company’s estimated value after the new investment is included.

Founder ownership after the round is the remaining ownership after subtracting the investor’s new equity percentage in a simplified model.

Sanity check helps confirm whether the calculated values satisfy the relationship between investment, pre-money valuation, post-money valuation, and investor ownership.

Pre-Money vs Post-Money Example Difference

The same investment can produce different ownership percentages depending on whether the valuation is quoted as pre-money or post-money.

This difference matters during fundraising negotiations because it changes dilution and ownership.

Practical Uses of a Pre & Post-Money Valuation Calculator

• estimate investor ownership from a funding offer
• convert between pre-money and post-money valuation
• understand founder dilution in a simple priced round
• check whether a term sheet quote is pre-money or post-money
• estimate implied valuation from investment and equity percentage
• compare different fundraising offers
• prepare basic startup financing examples for discussion

Common Mistakes to Avoid

• Do not confuse pre-money valuation with post-money valuation.
• Do not calculate investor ownership using pre-money valuation when the deal is based on post-money ownership.
• Do not ignore option pool increases, because they can affect founder dilution.
• Do not treat a simple calculator result as a full cap table.
• Do not assume equity percentage alone explains all investor economics, because liquidation preferences and share rights can matter.
• Do not confuse equity valuation with enterprise value.
• Do not use this calculator as legal, tax, accounting, or investment advice.

Formula Summary

References

1. AjaxCalculators live Pre & Post-Money Valuation Calculator
2. Corporate Finance Institute: Pre-money valuation definition and post-money formula
3. Carta: Pre-money vs post-money valuations and investor ownership
4. Investopedia: Pre-money vs post-money valuation explanation

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Disclaimer: This calculator is for educational and planning use only. Startup financing terms can be affected by securities law, tax rules, option pools, SAFEs, convertible notes, liquidation preferences, anti-dilution rights, preferred shares, voting rights, debt, and other legal documents. This tool does not provide legal, tax, accounting, investment, or fundraising advice. For real financing decisions, review the full term sheet and cap table with qualified professionals.