Startup Dilution Calculator
See what founders keep after every SAFE, priced round and option pool top-up. Built on the cap table sheet from our financial models, with 2026 medians as the starting point.
Last updated: September 2026
Contributed and reviewed by: Igor Shaverskyi
Created by: Waveup finance and content teams
Start from the 2026 medians and replace them with your own round plan. Ownership is fully diluted and includes the unallocated option pool.
Valuation is pre-money for a priced round and the post-money cap for a SAFE. Pool after is the unallocated pool you agree to show after the round, as a share of fully diluted equity.
Swipe sideways to see the later rounds.
| Ownership after | Founding | Pre-seed | Seed | Series A | Series B |
|---|---|---|---|---|---|
| Founder 1 | 55.0% | 47.7% | 33.9% | 25.8% | 21.8% |
| Founder 2 | 45.0% | 39.0% | 27.7% | 21.1% | 17.9% |
| Option pool | – | – | 12.0% | 15.0% | 15.0% |
| Pre-seed investors | – | 13.3% | 9.5% | 7.2% | 6.1% |
| Seed investors | – | – | 16.9% | 12.8% | 10.9% |
| Series A investors | – | – | – | 18.0% | 15.2% |
| Series B investors | – | – | – | – | 13.1% |
| Founders together | 100.0% | 86.7% | 61.6% | 46.9% | 39.7% |
| Raised in the round | – | $2.0M | $4.1M | $14.4M | $25.0M |
| Post-money valuation | – | $15.0M | $24.3M | $80.0M | $191.0M |
| Price per share | – | $1.30 | $1.50 | $3.75 | $7.58 |
| Pool top-up in the round | – | – | 12.0% | 5.9% | 2.3% |
Post-money SAFEs sell a fixed share of the company (amount ÷ cap) and convert before the next priced round. Pool top-ups are agreed as a share of the post-round fully diluted equity. Read the mechanics in our dilution guide.
How to use the dilution calculator
Type in the rounds you plan to raise and the calculator rebuilds your cap table after each one: what the new investors get, how the option pool top-up lands, and what the founders keep. The defaults are the 2026 medians from Carta's benchmark data, the same figures we use in our guide to dilution per round, so the first thing you see is what a typical software company gives up between founding and Series B.
Three things to check as you play with it:
- Raise what the milestone needs. A bigger round at the same valuation is more dilution, not more safety. Set the raise to the cash that gets you to the next proof point, then look at the price.
- Watch the pool, not just the investor. The option pool top-up is the dilution founders forget. Switch the pool timing between "in the pre-money" and "after the round" to see who pays for it.
- Convert the SAFEs before you price. Every post-money SAFE sells a fixed share of the company at signing. Enter them as their own round so the seed price reflects them.
How the maths works
Ownership is measured on a fully diluted basis, which means every share that exists or is promised counts in the denominator: founders, investors, and the whole option pool, allocated or not. A priced round sets a pre-money valuation, and the price per share is that valuation divided by the shares that exist before the new money comes in. When the term sheet asks for the pool to be topped up "in the pre-money", those new pool shares are added before the price is set, so the top-up comes out of the existing holders and the investor pays the lower price. Sized after the round, the top-up dilutes everyone, the new investor included. That is the difference the timing switch shows.
A post-money SAFE is simpler and harsher: the holder owns the investment divided by the cap, locked at signing, and later SAFEs dilute the founders rather than the earlier SAFE holders. The calculator converts each SAFE into shares before the next priced round, which is how it plays out on a real cap table.
What the benchmarks say
On the 2026 medians a founding team gives up a little under a fifth of the company at seed and roughly the same again at Series A, with the pool top-ups on top. The dilution guide walks through the round-by-round numbers with sources, and the seed round benchmarks page covers round sizes and valuations in more depth. If the calculator shows you under 40% after Series A, the fix is usually the round plan, not the negotiation.
Frequently asked questions
How much dilution is normal per round?
Around 15 to 20% at seed and Series A, falling to 10 to 15% at Series B and under 10% from Series C on, before option pool top-ups. The dilution guide has the 2026 medians by stage with sources.
Does the option pool count as dilution?
Yes. The pool is part of the fully diluted share count, so a top-up reduces every existing holder's percentage. When it is sized in the pre-money, the founders and earlier investors absorb all of it; the new investor's percentage is unaffected.
How does a SAFE convert into equity?
A post-money SAFE converts at the next priced round into a share of the company equal to the amount invested divided by the valuation cap, or at the round price if that is lower. The calculator models the cap case, which is the usual outcome when the round is priced above the cap.
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 money raised. The investor's ownership is the raise divided by the post-money. Our post-money valuation guide covers the calculation and the traps.
Can I model my own cap table with this?
Yes for the round plan, no for the fine print. Preference stacks, pro rata rights, convertible notes with discounts and interest, and secondary sales need a full model. That is the work we do inside a financial model for a raise, and it is where the cap table sheet this calculator is based on lives.
Planning a round? Waveup has supported founders through 884 projects since 2014, with $3B+ raised by clients. See how we run a raise.