Pre-Money / Post-Money Valuation Calculator
Startup valuation arithmetic.
Calculate pre-money valuation, dilution, and price per share for a VC deal from investment amount and post-money valuation.
What this tool does
This calculator performs the core arithmetic of seed and early-stage funding rounds. It takes an investment amount, post-money valuation, and founder share count to compute pre-money valuation, new investor ownership percentage, dilution to existing shareholders, and the implied price per share. The post-money valuation is the primary driver—it anchors both the pre-money figure and investor stake. Results illustrate how capital infusion affects ownership splits and per-share economics in a single round. This is useful for modelling funding scenarios or understanding term sheet mechanics. The calculator assumes a single investor, no employee option pool adjustments, and no other share classes or preferences—it models basic equity math only and does not account for tax treatment, legal costs, or future dilution from subsequent rounds.
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Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Pre-money/post-money valuation calculator computes the core arithmetic of every venture capital deal. Pre-money valuation = company value before investment. Post-money valuation = pre-money + investment. Investor ownership % = investment / post-money. Founder dilution = same as investor ownership.
Example: founders raise 2M at 10M post-money valuation. Pre-money = 8M. Investor gets 2M / 10M = 20% ownership. Founders diluted from 100% to 80%. If founders held 1M shares pre-round, price per share = 8M / 1M = 8. Investor receives 250,000 new shares (2M / 8).
Watch for valuation games: 'we raised at 10M valuation' could mean either pre or post. Pre-money is the headline founders prefer (sounds bigger). Post-money is what investors track. Clarifying which one is meant avoids confusion. Down rounds (post-money lower than previous post-money) trigger anti-dilution provisions, often punishing founders heavily through ratchet adjustments.
Run it with sensible defaults
Using investment amount of 2,000,000, post-money valuation of 10,000,000, founder shares pre-round of 1,000,000, the calculation works out to 8,000,000.00. The defaults are meant as a starting point, not a recommendation.
The levers in this calculation
The inputs — Investment Amount, Post-Money Valuation, and Founder Shares Pre-Round — do not pull with equal force. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.
How the math works
Pre-money = post-money - investment. Investor % = investment / post-money. Price per share = pre-money / founder shares pre-round.
Why run this
Running the numbers makes the trade-offs concrete. Small changes in the inputs can move the result more than intuition suggests, which is hard to judge without working it out.
What this doesn't capture
This is a simplified model that holds its assumptions constant. Real outcomes vary with market conditions, costs, taxes, and timing, so the figure is best read as one scenario rather than a forecast.
£2,000,000 at £10,000,000 post-money on 1,000,000 shares = $8,000,000.00.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
The calculator computes pre-money valuation by subtracting the investment amount from the post-money valuation. It then determines the investor's ownership percentage by dividing the investment by the post-money valuation. The price per share is derived by dividing the pre-money valuation by the number of founder shares outstanding before the round. The model treats the post-money valuation as fixed and assumes all investment proceeds are allocated toward equity issuance. It does not account for transaction costs, legal fees, dilution from future rounds, option pools, or variations in share class structures. Results represent the arithmetic relationship between these inputs at a single point in time.
References
Frequently Asked Questions
Pre-money or post-money?
What's a fair valuation?
Anti-dilution protection?
Option pool impact?
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