Startup Equity Split Calculator
Startup & Fundraising
Quick Answer
Describe each co-founder's role, contribution, and commitment. Paste into Claude or ChatGPT. Get equity split scenarios with vesting recommendations and dilution analysis through future rounds.
What You Get
An equity split analysis covering contribution-based allocation scenarios, standard vesting schedule recommendations, cliff and acceleration provisions, dilution impact through multiple funding rounds, and a plain-English explanation of the equity structure.
Who Is This For
Founding teams negotiating their initial equity split, startup advisors helping founders structure co-founder agreements, and early-stage startups setting up their cap table.
About This Template
Co-founder equity splits are one of the most consequential decisions a founding team makes — and one of the hardest to reverse. A fair split accounts for past contributions, future roles, opportunity cost, and commitment level. This template guides founding teams through their individual contributions and roles, then uses AI to produce equity split scenarios based on different allocation methodologies, vesting schedule recommendations, and a long-term analysis of how the initial split affects control through multiple funding rounds.
Fill In Your Details
Your company name
For each founder: name, role, past contributions, future commitment, salary deferral. e.g. Founder A: CEO, full-time from start, $0 salary, prior industry connections
Who contributed the original idea, any existing IP, prior work that forms the basis of the company
e.g. 10 percent of fully diluted shares for future employees
e.g. Seed $1M, Series A $5M, Series B $15M
Gather these details then use them to fill in the prompt below.
AI Prompts
Generate equity split analysis
Paste this prompt into Claude or ChatGPT with your founder details filled in.
You are a startup lawyer helping a founding team determine their equity split. Using the information below, produce an equity split analysis. Company: [company_name] Founders: [founders] IP contribution: [intellectual_property] Option pool: [option_pool_size] Future rounds: [future_rounds] Produce: 1. Contribution Assessment — evaluate each founder's contributions across idea, IP, commitment, salary deferral, and domain expertise 2. Equity Split Scenarios — 3 allocation models: equal split, contribution-weighted, and dynamic split 3. Recommended Split — your recommended allocation with rationale 4. Vesting Schedule — recommended vesting structure with cliff and acceleration provisions 5. Option Pool Impact — how the pool interacts with founder equity 6. Dilution Through Future Rounds — show founder ownership at current, post-seed, post-Series A, and post-Series B 7. Plain English Summary — what this split means for each founder in practical terms Flag any red flags: unequal commitment levels, missing vesting, or IP ownership issues. Be specific about the numbers.
Sample Output
This is an example of what AI produces when you use this template.
Equity Split Scenarios
Scenario 1 — Equal Split (50/50): Simple and preserves co-founder relationship but does not account for Founder A's full-time commitment versus Founder B's planned part-time role for first 6 months. Scenario 2 — Contribution-Weighted: Founder A 55%, Founder B 45% based on weightings: idea (equal), IP (Founder A advantage), commitment (Founder A full-time from day 1), domain expertise (Founder B advantage). Scenario 3 — Dynamic Split: 50/50 initially with 5 percent of Founder B's shares reallocating to Founder A if Founder B does not transition to full-time by month 6. Recommended: Scenario 2 at 55/45 with 4-year vesting and 1-year cliff.
Dilution Through Future Rounds
Current split: Founder A 55%, Founder B 45% (100% combined before option pool). After 10% option pool: Founder A 49.5%, Founder B 40.5%. Post-Seed ($1M at $8M pre): Founder A 44%, Founder B 36%, Option pool 10%, Seed investors 10%. Post-Series A ($5M at $20M pre): Founder A 34.1%, Founder B 27.9%, Option pool 10%, Seed 7.7%, Series A 20%. Post-Series B ($15M at $60M pre): Founder A 23.9%, Founder B 19.5%, Option pool 8%, Seed 5.4%, Series A 14%, Series B 20%. Combined founder ownership of 43.4% post-Series B is healthy and above the threshold that typically concerns later-stage investors.