Seed, Series A and Series B Benchmarks 2026: Average Seed Round Size to Series B Valuation

The average seed round size is one of the most searched fundraising numbers, and one of the hardest to pin down. Every data source gives a different answer, and most posts don’t say which quarter or which companies the number comes from. This report puts the 2026 seed, Series A and Series B benchmarks from three named sources side by side, with the period for each. If you work in the sector, read about raising capital for healthcare companies.

At Investor Links, we build investor lists by stage and check size for founders every week, so we look at these numbers all the time. Keep in mind that 2026 data is still partial. The latest period in each source is Q2 2026 or the first nine months of the year. For a deeper walkthrough, see AI startup investor outreach from seed to Series B.

Why do seed, Series A and Series B benchmarks disagree?

Because each source counts different deals. Here’s what each one covers:

• Carta uses rounds raised by US companies on its cap table platform. Its Round Benchmarking Tool covers about 20,000 primary equity rounds since January 2021 and leaves out bridge rounds and convertible instruments. Carta quotes post-money valuations.
• The PitchBook-NVCA Venture Monitor tracks US venture deals across the market. Its latest data runs to September 30, 2026, and it quotes pre-money valuations.
• Wilson Sonsini’s Entrepreneurs Report uses deals the law firm worked on. Its latest edition covers Q2 2026, and it also quotes pre-money valuations.

Pre-money is the value before the new money comes in. Post-money is pre-money plus the new money. Always compare pre with pre, and post with post.

When people search for an “average,” the number they actually want is the median, because a few giant rounds pull averages way up. Every figure below is a median.

What is the average seed round size in 2026?

Somewhere between $3 million and $4.5 million at the median, depending on the source:

• Carta, Q2 2026: a median seed round of $4.5 million at a $23.9 million post-money valuation, with 19.4% dilution.
• PitchBook-NVCA, 2026 through September 30: a median seed deal of $3.0 million, down from $3.4 million in 2025, at an $18.3 million pre-money valuation, up from $16.0 million.
• Wilson Sonsini, Q2 2026: a median seed pre-money valuation of $23.0 million, down from $35.0 million in Q1 2026.

The range around the median is wide. In Carta’s Q1 2026 report, seed post-money valuations from Q2 2025 through Q1 2026 ran from $12.4 million at the 25th percentile to $35 million at the 75th.

Seed money on Carta is also shrinking. In a July 2026 Carta update, seed capital recorded on Carta fell from $6.5 billion in H1 2025 to $3.8 billion in H1 2026. Deal count is down too: Carta’s Q1 2026 report counted 381 seed rounds, down from 481 in Q1 2025.

What are the Series A benchmarks for 2026?

Series A is where the sources agree the least:

• Carta, Q2 2026: a median Series A of $14.7 million at a $76.3 million post-money valuation, with 18.7% dilution.
• PitchBook-NVCA, 2026 through September 30: a median Series A deal of $17.4 million, up from $13.7 million in 2025, at a $60.3 million pre-money valuation, up from $48.1 million.
• Wilson Sonsini, Q2 2026: a median Series A pre-money valuation of $80.0 million.

The top of the market has pulled far away from the middle. Carta put the 90th percentile Series A post-money valuation at $300 million in Q1 2026. And in Q2 2026, the top 5% of Series A companies on Carta raised at valuations of over half a billion dollars.

What is the average Series B round size and Series B valuation?

Here’s what the three sources show for Series B in 2026:

• Carta, Q2 2026: a median Series B of $23.3 million at a $166.2 million post-money valuation, with 13.4% dilution.
• PitchBook-NVCA, 2026 through September 30: a median Series B deal of $39.5 million, up from $30.0 million in 2025, at a $187.0 million pre-money valuation, up from $140.0 million.
• Wilson Sonsini, Q2 2026: a median Series B raise of $35.0 million and a median pre-money valuation of $290.5 million. The firm says this likely reflects a small but growing number of outsized rounds, not a broad repricing.

Series B valuations are rising faster than earlier stages. Carta’s Q1 2026 report found Series B primary pre-money valuations up 17.2% year over year, while seed and Series A pre-money valuations fell 6.6% and 7.1%. Carta’s median Series B post-money in Q1 2026 was $177 million, and the 90th percentile crossed $1 billion for the first time in its data.

But fewer dollars are going into Series B on Carta. Its July 2026 update shows Series B capital falling from $13.5 billion in H1 2025 to $10.4 billion in H1 2026, while Series A held flat at $12.7 billion.

How much does AI change these benchmarks?

A lot. PitchBook-NVCA puts median AI pre-money valuations for 2026 through September 30 at $21.0 million at seed, $78.0 million at Series A and $266.3 million at Series B. For all deals, the same report shows $18.3 million, $60.3 million and $187.0 million.

The premium isn’t spread evenly across AI companies. At Series A in Q1 2026, Carta found a median post-money of $55 million for non-AI companies, $65 million for AI applied companies and $300 million for AI foundational model companies. If you’re not training your own models, the headline AI numbers probably don’t apply to you.

How long does it take to get from seed to Series B?

Usually around two years per round. In Carta’s Q1 2026 data, the median time between seed and Series A was two years, and between Series A and Series B it was 2.1 years. The median company raising a Series A was 2.8 years old. Plan your runway around that.

How should you use these benchmarks?

From our work with founders, here’s how to use them:

• Pick the source that matches you. If you’re a US startup that will use a cap table platform, Carta is close to your peer group. For the whole US market, use PitchBook-NVCA.
• Match the period. Don’t compare your 2026 round with a 2024 median.
• Start with what you need. Work out the cash you need for your next milestone. The valuation usually follows from that and from how much you’re willing to sell.
• Use benchmarks to pick investors. A median Series B is a very different check from a median seed. Make sure every investor on your list writes checks at your stage. Our report on how many investors to contact and our family office vs. VC report can help you build that list.

How does Investor Links help with your round?

We build a checked list of investors who fit your stage, sector and round size, write outreach for each investor’s focus, and run it on LinkedIn and email through HeyReach and Instantly. Warm replies go straight to you, and you get weekly numbers on opens, responses and meetings. We don’t promise funding. Book a free call to talk about your round, or see our investor outreach benchmarks and other fundraising reports.

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