Startups · Accelerators
Inside Y Combinator: the deal, the batch, the odds
How the accelerator behind Airbnb and Stripe invests, and how to tell if one fits you.
Y Combinator is a startup accelerator in San Francisco that invests $500,000 in each company it accepts, runs a three-month program four times a year and ends each batch with Demo Day for investors. It funded early versions of Airbnb, DoorDash, Stripe and Reddit, and its terms set the standard for early-stage deals.
Y Combinator, usually called YC, says that in 2005 it “developed a new model of startup funding”: invest a small amount in many very early companies at once, then help them grow together in a short, intense program. Its home page cites $1.3 trillion in combined valuation for its companies and lists alumni that went public, including Dropbox (2018), Airbnb and DoorDash (2020), Coinbase and GitLab (2021), Instacart (2023) and Reddit (2024).
This guide explains the YC deal in plain numbers, what a batch looks like, how to apply and how YC compares with other accelerators and paths. If you are new to startup money, read our startup funding stages guide first.
What a startup accelerator is
A startup accelerator is a fixed-length program, usually about three months, that invests a small amount of money in a group of early companies, called a batch or cohort, in exchange for equity. Founders get mentoring, a peer group and an introduction to investors at the end. Techstars, another large accelerator, describes its programs as “three months of intensive, mentorship-driven support.”
Accelerator, incubator or angel investor?
| Option | What you get | What it costs you |
|---|---|---|
| Accelerator (YC, Techstars) | Cash, a short structured program, a cohort and Demo Day | Equity, often through SAFEs; three months of full-time focus |
| Incubator | Space, services and advice over a longer period | Often rent or fees; sometimes equity |
| Angel investor | Cash and personal advice | Equity; terms vary by investor |
| Bootstrapping | Full control | Growth limited to your own revenue and savings |
The YC standard deal, in plain numbers
YC publishes its deal on its website. It invests $500,000 in every accepted company through two SAFEs (simple agreements for future equity) signed at the same time:
- $125,000 on a post-money SAFE for 7%. YC owns 7% of the company, including any option pool, after the SAFE converts in the first priced round.
- $375,000 on an uncapped SAFE with a “most favored nation” (MFN) clause. It has no valuation cap of its own. It converts on the best terms, usually the lowest cap, of any SAFE the company issues between the start of the batch and its priced round.
- No fees and no milestones. YC says it charges companies nothing to participate and commits the money the day a company is accepted.
- A pro rata right. YC may invest in later rounds to keep its ownership share.
What the first $125,000 implies
Calculated from YC’s published terms: $125,000 divided by 7% is about $1.79 million. The second SAFE converts later at a cap set by the company’s next SAFE investors.
YC gives its own example of the second SAFE. If the company later raises SAFE money at a $15 million post-money cap, the $375,000 converts into 2.5%. Together with the first SAFE, YC would then own 9.5% after the priced round, before later dilution.
YC’s ownership in its own example ($15M post-money cap)
- 90.5%Founders, team and other investors
- 7%YC: $125,000 post-money SAFE
- 2.5%YC: $375,000 MFN SAFE
Based on YC’s published example; actual ownership depends on the caps and amounts of later rounds.
YC created the SAFE in 2013 (written by Carolynn Levy) and standardized on the post-money SAFE in 2018. It is a short contract: an investor gives money now and receives shares later, when the startup raises a priced round. YC notes a SAFE is not debt, with no interest or maturity date. The post-money cap is the company’s value after the SAFE money is counted, which makes dilution easy to calculate.
YC invests in corporations formed in the United States, Canada, the Cayman Islands or Singapore. Companies formed elsewhere may need to restructure under a parent company in one of those places. Our California business structure guide explains why venture-backed startups usually form as corporations rather than LLCs.
What happens during a YC batch
YC runs four batches a year: winter, spring, summer and fall. Each lasts about three months in person at YC’s San Francisco campus and opens with a three-day kickoff. Founders work closely with YC partners, many of them former founders, and with the other companies in the batch. The program ends with Demo Day, when each company presents to investors.
A typical accelerator timeline
- ApplyAn online application about the founders, the product and its progress. YC says most interviews happen by video conference, with decisions usually made the same day.
- Accept and signYC invests as soon as a company is accepted, not when the batch starts.
- KickoffThree days in person to meet partners and the batch.
- Build and sellWeeks of shipping product, talking to users and tracking growth, with partner office hours and batch events.
- Demo DayA short pitch to investors that often starts fundraising for the next round.
- Alumni networkAccess to the YC founder community continues after the program.
How to apply, and the Winter 2027 dates
YC’s apply page lists the Winter 2027 batch, running January to March. The on-time deadline was Nov. 2, 2026 at 8 p.m. Pacific; YC says late applications are still considered, though it cannot promise timing, and on-time applicants hear by Dec. 11. Accepted companies also get access to more than $12 million in partner credits and deals from cloud, AI and payment companies.
- Show progress, not plans. Users, revenue, a working product or fast learning count more than a polished slide.
- Explain the problem clearly. One or two sentences on who has the problem and why now.
- Highlight the team. Why you are the right founders to build this, with specific evidence.
- Be concise and honest. Plain, specific answers are easier to judge than buzzwords.
- Apply again. If you are not accepted, keep building and apply to a later batch with new progress.
A good application often reads like a tight pitch. Our pitch deck guide covers how to tell the problem, solution and traction story in a few lines.
Free YC resources for every founder
You do not need to be accepted to learn from YC. Startup School is a free online course on how to start a startup, taught by YC partners and guest founders. YC says it takes about seven weeks at one to two hours a week. Its co-founder matching platform reports more than 100,000 matches made. YC’s standard SAFE documents are also free to download, though founders should have a lawyer review any financing.
Is an accelerator right for your company?
When YC-style funding fits, and when it does not
| Question | Good fit | Poor fit |
|---|---|---|
| Growth goal | A large market and a plan to grow fast | A steady local business or lifestyle company |
| Next funding | You expect to raise venture capital | You plan to grow from revenue or loans |
| Time | Founders can work full time for three months in person | Founders cannot leave jobs or family |
| Equity | Giving up 7% or more for capital, network and credibility is worth it | You want to keep 100% ownership |
Most small businesses, such as a café, a contractor or a consulting firm, are not built for venture capital, and that is fine. Loans, grants and revenue are better tools for them; our how to become an entrepreneur guide compares the paths. For a startup aiming at a large market, an accelerator can compress years of learning into months.
Common mistakes
- Treating acceptance as success. The money and Demo Day help, but customers decide the outcome.
- Ignoring the MFN SAFE. Its conversion depends on your next SAFE cap, so model dilution before you raise.
- Stacking too many SAFEs. Several caps can dilute founders more than expected at the priced round.
- Applying with only an idea. Evidence that users want the product makes the strongest case.
- Choosing an accelerator by brand alone. Compare terms, partners, alumni results and fit with your industry.
Key terms
- Accelerator: a fixed-length program that invests in a batch of startups for equity and ends with a demo day.
- SAFE: a simple agreement for future equity; money now, shares at the next priced round.
- Post-money valuation cap: the maximum company value, including the SAFE money, at which a SAFE converts.
- MFN clause: “most favored nation”; the SAFE takes the best terms given to later SAFE investors.
- Demo Day: the event where a batch of startups pitches to investors.
The bottom line: Y Combinator offers $500,000, a three-month program and a large network for about 7% plus a second SAFE that converts later. For founders chasing fast growth and venture capital, it is the benchmark deal; for most small businesses, other funding paths fit better.
Free help in the Sacramento region
You do not have to work through these decisions alone. SCORE Sacramento pairs owners with volunteer mentors, many of them retired executives, bankers and accountants, at no cost. The Sacramento Valley Small Business Development Center offers free one-on-one advising on financing, budgeting and financial statements. The SBA’s Sacramento District Office can explain loan programs and connect you with lenders, and community lenders such as California Capital and Opening Doors serve owners who need smaller loans or extra support. Browse our Business Resources and the free business help guide for more.
Key takeaways
- Y Combinator invests $500,000 per company: $125,000 for 7% on a post-money SAFE plus $375,000 on an uncapped MFN SAFE.
- In YC’s own example, a later $15 million SAFE cap gives YC 9.5% in total.
- YC runs four batches a year, each about three months in San Francisco, ending at Demo Day.
- The Winter 2027 batch runs January to March; on-time decisions arrive by Dec. 11, 2026.
- Startup School and YC’s SAFE documents are free for any founder.
Frequently asked questions
What is Y Combinator?
Y Combinator is a startup accelerator in San Francisco. It invests 500,000 dollars in each accepted company, runs a three-month program four times a year and ends each batch with Demo Day for investors.
How much equity does Y Combinator take?
YC takes 7 percent for its first 125,000 dollars through a post-money SAFE. Its other 375,000 dollars is an uncapped SAFE that converts on the terms of the company’s next SAFE, such as 2.5 percent at a 15 million dollar cap in YC’s example.
Does Y Combinator charge fees?
No. YC says it charges companies no fees to participate. It invests when a company is accepted and does not tie the money to milestones.
When are the Y Combinator deadlines?
YC runs winter, spring, summer and fall batches. For Winter 2027, the on-time deadline was November 2, 2026, late applications are still considered, and the batch runs from January to March.
Is there a free way to learn from Y Combinator?
Yes. Startup School is a free online course run by YC that takes about seven weeks at one to two hours a week, and it includes a co-founder matching platform.
Sources
- Y Combinator: home page
- Y Combinator: The YC Deal
- Y Combinator: Apply to Y Combinator
- Y Combinator: About
- Y Combinator: Documents (SAFE financing documents)
- Y Combinator: Startup School
- Techstars: Accelerators
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