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Free Cap Table / Equity Dilution Calculator
Walk through your cap table from founding through Series A. Models founder split, pre-priced-round option pool (dilutes founders), SAFE conversion at min(cap, pre-money), and priced rounds where investor % = raise / post-money. Shows the full ownership table at each stage.
Founders
Founder %s are normalized to sum to 100 automatically.
Option pool
Typical: 10-15%. Investors often require the pool be created BEFORE their round (dilutes founders, not investors). 0 to skip.
SAFE / convertible notes
SAFEs convert at min(valuation cap, next priced round pre-money) per standard YC SAFE.
Seed round
Set raise to 0 to skip. Post-money = pre-money + raise.
Series A
Final ownership
47.6%
Founder total after 3 dilution events.
Founder total at end
47.6%
Founding
| Stakeholder | Ownership % |
|---|---|
| Alice | 50.00% |
| Bob | 50.00% |
Option pool (10%)
| Stakeholder | Ownership % |
|---|---|
| Alice | 45.00% |
| Bob | 45.00% |
| Option Pool | 10.00% |
Seed
Post-money: $10,000,000 · Raised: $2,000,000
| Stakeholder | Ownership % |
|---|---|
| Alice | 33.35% |
| Bob | 33.35% |
| Option Pool | 7.41% |
| SAFE 1 | 5.88% |
| Seed Investors | 20.00% |
Series A
Post-money: $28,000,000 · Raised: $8,000,000
| Stakeholder | Ownership % |
|---|---|
| Alice | 23.82% |
| Bob | 23.82% |
| Option Pool | 5.29% |
| SAFE 1 | 4.20% |
| Seed Investors | 14.29% |
| Series A Investors | 28.57% |
Founders
47.6%
Investors
47.1%
📐 Open methodology, sources & limitations
Formula
Founders: initial split normalized to sum to 100%. Option pool (pre-money): dilution factor = 1 − poolPct/100 every existing holder × dilution factor; Option Pool added at poolPct. SAFE conversion at a priced round: effective pre = min(SAFE valuation cap, round pre-money) SAFE ownership %= principal ÷ (effective pre + principal) Priced round (Seed / Series A): post-money = pre-money + new raise investor % = new raise ÷ post-money total new % = investor % + Σ SAFE % existing holders × (1 − total new % / 100); new holders added.
Assumptions
- Single class of stock — no common vs preferred distinction.
- The option pool is created entirely pre-money, so it dilutes founders only (not the incoming investor).
- SAFEs convert at min(valuation cap, priced-round pre-money) — the standard YC post-money SAFE interpretation.
- Option pool input is clamped to a 0–50% range; founder splits are normalized to total 100%.
- Ownership percentages are recomputed and re-normalized to ~100% after every round.
Sources
- Y Combinator — Post-Money SAFE primer and conversion mechanics
- Standard venture-financing dilution math (pre-money / post-money ownership)
This tool does NOT model:
- Multi-tier valuation caps and discount rates on convertible notes
- MFN (most-favored-nation) clauses
- Anti-dilution provisions (full-ratchet or weighted-average)
- Liquidation preferences (1x, participating, multiples)
- Warrants, secondary sales, and share buybacks
- Multiple share classes and pro-rata participation rights
Last reviewed: 2026-05-20
This methodology section exists so you can verify the math. We show our formulas because you deserve to know how a number was calculated. This is calculation transparency, not financial advice.
How dilution works
Every time your startup raises money or issues equity to employees, existing holders get diluted. A typical two-cofounder startup going through a seed + Series A with a SAFE and an option pool ends up with founders holding roughly 50-55% combined, investors holding 30-40%, and option pool 10-15%. This calculator walks through each round and shows the ownership table at each stage.
The basic dilution formula
When new shares are issued (new investor money or new option pool), existing holders shrink proportionally. If new shares = X% of post-money cap table, every existing holder loses (X%) of their ownership in relative terms. Mathematically: new_ownership = old_ownership × (1 − newSharesPct).
Option pool — the pre-money trick
Investors usually require an option pool to be created BEFORE their round closes, sized to fund 12-18 months of new hires. The pool comes out of the pre-money valuation, which means it dilutes FOUNDERS and not the new investor. Pool size 10-15% is standard for early-stage rounds. Negotiating this number with your lead investor is one of the highest-leverage moments in a fundraise.
SAFE conversion math
A SAFE (Simple Agreement for Future Equity) is essentially a deferred equity purchase. It converts to actual shares at the next priced round. Conversion price = min(SAFE valuation cap, priced round pre-money) — meaning if the priced round is at $20M pre and your SAFE has a $10M cap, the SAFE holder gets equity as if they invested at $10M. Their effective ownership = SAFE principal ÷ ($10M + SAFE principal).
Multiple SAFEs with different caps and discount rates can stack and create surprisingly large dilution at the priced round. The "SAFE math" is the most error-prone part of cap-table modeling; getting it wrong is one of the most common founder mistakes.
Typical Series A founder dilution
For a healthy seed→Series A trajectory: founders start at 100%, drop to ~85% after option pool, ~65% after seed, ~45% after Series A. By Series C, founders typically hold 15-25% combined. The trade-off: dilution is the cost of capital — venture-funded startups that succeed make founders rich on the smaller percentage of a much bigger pie.
Frequently Asked Questions
How is dilution calculated?+
When new shares are issued (new investor money or option pool), existing holders shrink proportionally. New_ownership = old_ownership × (1 − newSharesPct). The new investor gets newMoney / postMoney of the company; everyone else gets diluted by that ratio.
What's a typical Series A dilution?+
Investors typically take 15-25% of the company in a priced round. With a 10-15% option pool added pre-round, total dilution event is 25-40% per priced round. Founders post-Series A typically hold 40-55% combined; post-Series B, 25-40%; post-Series C, 15-25%.
How does a SAFE convert?+
Standard YC SAFE converts at the next priced round at the LESSER of (a) the SAFE valuation cap or (b) the round's pre-money valuation. Effective ownership = SAFE principal ÷ (conversion price + SAFE principal). Multiple SAFEs with different caps stack and can create surprising dilution.
What's the option pool trap?+
Investors typically require the option pool to be created BEFORE their investment closes, sized to fund 12-18 months of hiring. Because the pool is "pre-money", it dilutes FOUNDERS and not the new investor. Negotiating pool size (10% vs 15% vs 20%) is one of the highest-leverage moments in a fundraise.
Pre-money vs post-money?+
Pre-money = company valuation BEFORE the round's new investment. Post-money = pre-money + new investment. Investor ownership = newInvestment / postMoney. A "$10M raise at $40M pre" means the investor invests $10M, the post-money is $50M, and the investor owns 20% (10/50).
What about liquidation preferences?+
Not modeled here. Most VC rounds include a "1× non-participating" preference, meaning investors get their money back first in a sale before founders see anything. For exit waterfall modeling, use Carta or a dedicated cap-table tool.
Should I do a SAFE or priced round?+
SAFEs are faster and cheaper to close ($1-3k in legal fees vs $30-50k for a priced round), making them dominant at pre-seed and seed. Priced rounds offer more certainty on dilution and are typically required at Series A+. Up to ~$3M raise, SAFE is usually right; above that, priced makes sense.
Is my data stored?+
No. All cap-table modeling runs in your browser. Founder names, financials, and round data never touch any server.
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