Business Tools
Use this startup dilution calculator to estimate how an investment and option pool change ownership percentages.
Live calculator
$9,500,000.00 post-money valuation.
Current ownership after investor dilution.
15.74% total point reduction from current ownership.
This does not model liquidation preferences, SAFEs, convertible notes, pro rata rights, anti-dilution terms, or pre-money option pool negotiation details.
Use this for planning and comparison. Contracts, collections, payables, tax timing, payroll, refunds, one-time bills, seasonality, and accounting treatment can change the real business result.
Quick answer
Startup Dilution Calculator calculates ownership after dilution from pre-money valuation, investment amount, option pool increase, and current ownership. The visible formula is Investor ownership = investment / (pre-money valuation + investment).
Formula
Investor ownership = investment / (pre-money valuation + investment)This simplified calculator does not model SAFEs, notes, preferences, pro rata rights, anti-dilution clauses, or detailed cap table terms.
How to use
Example
Calculator use
Before relying on it
Details
Keep pre-money valuation and investment amount aligned to the same scenario so ownership after dilution represents a consistent calculation.
The tool applies Investor ownership = investment / (pre-money valuation + investment) to the entered values, then keeps ownership after dilution, examples, assumptions, and limits visible for review.
Benchmarks
A broad planning signal when investment is small relative to valuation.
Investment size, valuation, and pool expansion all change ownership.
Whether the pool is created pre-money or post-money can materially change dilution.
Calculator accuracy
Investor ownership = investment / (pre-money valuation + investment)
Pre-money valuation, Investment amount, Option pool increase, Current ownership
Business results depend on contracts, accounting treatment, taxes, payment timing, refunds, collections, and operating assumptions.
June 6, 2026
Toolkit Shelf. Startup Dilution Calculator. Last reviewed June 6, 2026. https://toolkitshelf.com/tools/startup-dilution-calculator
FAQ
Startup dilution is the reduction in ownership percentage when new shares, investor ownership, or option pools are added.
No. Option pool timing and negotiation terms matter. This calculator is a simplified planning estimate.
No. Use a detailed cap table model or legal/finance advice for actual fundraising terms.
No. Business tools are scenario planners. Contracts, taxes, payment timing, accounting treatment, refunds, and legal requirements can change decisions.
Save the assumptions, compare a conservative scenario, and review the result with actual books, contracts, or an advisor before making a high-stakes decision.