ToolNestFree Cap Table Dilution Simulator
Last updated: October 22, 2026
Quick answer: Every funding round shrinks your slice of the company — the question is by how much, and whether the math still works for you. This free cap table dilution calculator models your startup's equity across multiple funding rounds: enter your starting cap table, any SAFEs or convertible notes, and each round's pre-money valuation, new money, and option-pool top-up. The simulator converts the notes, prices each round, and shows a round-by-round waterfall — your ownership percentage, your stake's dollar value, and your cumulative dilution after every round. Everything runs in your browser; nothing is uploaded or stored.
1. Starting cap table
Shareholders before any new rounds. The first row is tracked as your stake through every round.
2. SAFEs / convertible notes
These convert into shares at the first round, at the better of the valuation cap or the discount.
3. Funding rounds
Model up to 3 rounds in sequence. The new option-pool % is the target pool after the round (carved from pre-money, as investors require).
🔒 100% Private: Data never leaves your device.
Simplified model for planning, not legal or tax advice: SAFEs convert at the first round; option-pool top-ups are carved from pre-money (the investor-favorable convention); anti-dilution provisions, liquidation preferences, and secondary sales are not modeled. Confirm final numbers with your lawyer before signing.
✓ Free forever · ✓ No signup · ✓ Tool inputs stay in your browser — never sent to our servers.
How to Use the Cap Table Dilution Simulator
- Enter your starting cap table: each shareholder's name and share count. The first row is tracked as your stake through every round.
- Add any SAFEs or convertible notes with their principal, valuation cap, and discount — they convert into shares at the first round, at the lower of the cap price or the discounted round price.
- Model up to 3 rounds in sequence: round name, pre-money valuation, new money raised, and the target option-pool % after the round (the pool top-up is carved from pre-money, as investors require).
- Click Simulate dilution to see the round-by-round waterfall: price per share, new shares issued, dilution per round, your ownership %, and your stake's dollar value.
- Read the verdict badge: founder-friendly, typical early-stage, or heavy dilution — then tweak the numbers to compare term sheets before you sign.
Why Use Our Cap Table Dilution Simulator?
- Multi-round waterfall — model up to 3 sequential rounds and watch your ownership % and stake value evolve round by round.
- SAFE / note conversion — converts at the first round at the better of valuation-cap price or discounted round price.
- Option-pool top-ups — carved from pre-money the way investors require; see exactly how much of the dilution the pool causes.
- Dilution verdict badge — flags whether your cumulative dilution is founder-friendly, typical, or heavy for early-stage rounds.
- 100% client-side — sensitive cap-table numbers never leave your browser; no signup, no account.
Common Use Cases
- Comparing two term sheets: Run the same round at a $20M pre-money with a 15% pool vs. a $25M pre-money with a 20% pool — the higher valuation isn't always the better deal once the pool math is in.
- SAFE stack check: See exactly how your pre-seed SAFEs convert at the seed round — founders are often surprised how much the cap-vs-discount math moves their percentage.
- Option-pool negotiation: Model 10% vs. 15% pool top-ups to quantify, in your own percentage points, what the investor's pool demand actually costs you.
- Multi-round planning: Project your ownership through Seed, A, and B now, so you know whether you'll still clear the ownership threshold the next investor expects.
- Board and investor conversations: Walk in with a round-by-round waterfall instead of a single percentage — it shows you've modeled the economics, not just the headline valuation.
- Down-round scenario planning: Model the same $5M raise at a $25M pre-money and at a $10M pre-money before a bridge decision: 16.7% dilution versus 33.3% changes whether the bridge is worth taking at all.
- Pro-rata decisions: Work out what holding your percentage costs: if the round issues 2.5M new shares and you own 10%, you need 250,000 shares at the round price to stay flat — the waterfall shows the alternative (8% after a 20% round) so the choice is priced, not guessed.
- Hiring-plan pool sizing: Translate a hiring plan into pool math: if you need to hire five senior people, model a 10% pool against a 15% pool and see the founder-percentage cost of each before the investor's pool demand becomes a term-sheet argument.
Cap Table Dilution Simulator vs Alternatives
- calculatorshub.net's cap table dilution calculator: A quick single-round tool: enter existing and new shares, get a dilution percentage. Ours models up to 3 sequential rounds with SAFE conversion and option-pool top-ups — the full waterfall, not one number.
- Carta's cap table tools: The industry standard for managing a real cap table — deep, audited, and built for compliance. It's a platform with signup, not a quick what-if modeler. Ours is the scratchpad you use before anything goes into Carta.
- A spreadsheet / YC post-money SAFE template: Maximum flexibility and the founder community's default. But one formula typo silently corrupts everything, and multi-round waterfalls get fragile fast. Ours encodes the standard conventions (pool from pre-money, cap-vs-discount conversion) so the math can't drift.
- Your lawyer's model: Authoritative and deal-specific — the final word before you sign. It's also slow and billable by the hour. Use this simulator to arrive at that conversation already knowing which numbers matter.
- Post-money SAFE calculators (YC SAFE calculator clones): Excellent for one question: what does this stack of SAFEs convert into at this cap? They stop there — one instrument, one round, no pool top-ups, no second round. Ours sequences the SAFEs into the rounds and pools that follow them.
- Venture blogs' dilution tables: Worked examples with fixed numbers (the classic 'founder owns X% after Seed, A, B' posts) are great for learning the shape of dilution. They can't run your numbers — different starting split, different caps, different pools. Ours is the same math with your cap table in it.
Bottom line: for a single back-of-the-envelope dilution percentage, the thin one-round calculators do the job. When you're comparing term sheets or planning across Seed, A, and B — with SAFEs and pool top-ups in the mix — a multi-round waterfall is what actually answers the question.
Frequently Asked Questions
How do you calculate dilution percentage?
Dilution % = new shares issued ÷ total shares after issuance × 100. Example: a company with 10M shares issues 2.5M new shares in a round → 2.5M ÷ 12.5M = 20% dilution. Your ownership drops by the same factor even though your share count doesn't change.
Does dilution mean I lose shares?
No — you keep every share you own. Dilution shrinks your percentage of a bigger pie. If the round raises the company's value enough, your smaller slice can be worth more dollars than your bigger slice was before. That's why the simulator shows both ownership % and stake value.
What is the difference between a priced round and a SAFE?
A priced round sets a valuation and share price now. A SAFE (Simple Agreement for Future Equity) is a promise: money today, shares later — it converts at the next priced round at the lower of the valuation-cap price or the discounted round price. SAFEs defer the valuation argument but add dilution you must model.
What is an option pool top-up and why does it dilute me?
Investors usually require a pool of unissued shares for future hires — often 10–20% at seed — carved out of the pre-money valuation, which means founders absorb it. It shows up in the waterfall as part of each round's dilution.
How much dilution is normal per round?
A rough early-stage pattern: 15–25% per round is typical, with cumulative founder dilution of 40–60% by Series B being common. Below 15% a round is founder-friendly; above 30% a round deserves a hard look at whether the valuation justifies it.
What is the difference between pre-money and post-money valuation?
Pre-money is what the company is worth before the new investment; post-money is pre-money plus the new money. Price per share = pre-money valuation ÷ fully-diluted shares (including the option-pool top-up). The simulator uses this standard convention.
What happens to my ownership if I don't take up my pro-rata in the next round?
It falls by the round's dilution factor. If you own 10% and the round issues new shares equal to 20% of the post-round total, your stake becomes 10% × (1 − 0.20) = 8% — without selling a single share. Taking up your pro-rata means buying 10% of the new shares issued, which holds your percentage flat (at the round price, so it costs real money).
How do down rounds change the dilution math?
A lower valuation means more shares per dollar raised, so the same raise dilutes more. Raising $5M at a $25M pre-money issues shares worth 16.7% of the post-money company; the same $5M at a $10M pre-money issues 33.3% — double the dilution — before any option-pool top-up. That is why founders model the down-round case before signing a bridge, not after.
What are fully diluted shares, and why does the price per share use them?
Fully diluted shares = all issued shares + the unissued option pool + shares from converting SAFEs and notes. Price per share = pre-money valuation ÷ fully diluted shares. Using only issued shares overstates the price and understates everyone's dilution — the pool and the SAFEs are real future shares, so honest math counts them now.
When exactly do SAFEs convert — before or after the new money is priced?
At the round, into the round's share class: the pool top-up and the SAFE conversions set the fully diluted share count, the round price is computed from that count, and then the new money buys shares at that price. The sequence matters — converting after pricing would give the new investors a different (better) deal than the one they signed.
What is anti-dilution protection, and is it in this model?
Anti-dilution provisions adjust earlier investors' conversion price if a later round prices lower: broad-based weighted-average (the common, milder form) blends old and new prices; full-ratchet (rare, harsh) resets the old price to the new low price entirely. This simulator does not model anti-dilution — if your SAFEs or preferred shares carry it, treat the waterfall as a floor on dilution, not the final number.
Do secondary sales dilute me?
No. A secondary sale transfers existing shares from one holder to another — the share count doesn't change, so your percentage doesn't change either. Dilution only happens when the company issues new shares (a priced round, a pool top-up, a SAFE conversion). If the company itself buys back shares, the opposite happens: fewer shares outstanding means your percentage rises.