SBIR vs STTR: Which Federal Research Grant Fits Your Startup

Every founder who reads about federal research grants runs into the same fork: SBIR and STTR. They fund the same kinds of companies, cover the same phases, hand out similar dollar amounts, and go through similar review panels. So the question is fair — which one do you actually apply for?

The short version: the answer usually decides itself once you know two things. Does a research institution do meaningful work on your project? And does your principal investigator work at your company or somewhere else? Everything else is detail.

TL;DR

• SBIR and STTR are federal R&D grant programs for small businesses. Both fund Phase I (feasibility, $50K-$300K) and Phase II (development, $750K-$2M).
• The core difference: STTR requires a formal partnership with a research institution that does at least 30% of the work. SBIR lets the small business do up to 100% of the work in-house.
• PI employment rule: on SBIR the PI must be primarily employed (>50%) by the small business. On STTR the PI can be employed by the small business or the research partner.
• Pick STTR if you already have a university lab collaborator central to your project. Pick SBIR if the work happens in-house.

What SBIR and STTR Actually Are

Both are federal grant programs run under the Small Business Innovation Research and Small Business Technology Transfer statutes. Eleven federal agencies participate in SBIR and five of those also run STTR (DOD, HHS/NIH, NSF, DOE, NASA). Total spending across both programs runs about $4B per year — the largest source of non-dilutive R&D funding in the US.

Both programs share the same phased structure:

• Phase I — feasibility. Award size $50K-$300K depending on agency. Typical period 6-12 months.
• Phase II — full development. Award size $750K-$1.75M depending on agency; NIH goes to $2M and DOD sometimes goes higher. Typical period 24 months.
• Phase III — commercialization. No new set-aside funding, but agencies can issue sole-source Phase III contracts to a Phase II winner. This is where the real money is over a company's lifetime.

If you're new to federal R&D grants, start with our complete guide to federal grants for small businesses — it covers the SAM.gov and Grants.gov plumbing that both SBIR and STTR sit on top of.

The Core Difference in 60 Seconds

| Rule | SBIR | STTR | | --- | --- | --- | | Research partner required | No | Yes — at least one non-profit research institution | | Small business share of work | At least 67% (Phase I), 50% (Phase II) | At least 40% | | Partner (research institution) share | Up to 33% (Phase I), 50% (Phase II) | At least 30% | | Principal Investigator employment | Primarily (>50%) at the small business | Can be at the small business OR the research partner | | Agencies participating | 11 (DOD, HHS, NSF, DOE, NASA, USDA, EPA, DHS, DOT, ED, DOC) | 5 (DOD, HHS/NIH, NSF, DOE, NASA) | | Award sizes | Same across programs at each agency | Same across programs at each agency | | Success rates | Similar to STTR at most agencies | Similar to SBIR at most agencies | | IP ownership | Company retains | Company retains, per negotiated allocation agreement with partner |

If you take one thing from this table: the primary variable is who does the work. If a university or federally funded research center is central to your technical plan, STTR is a fit. If your team can carry the science in-house, SBIR is a fit.

Which One Fits Your Situation

Instead of a table this time, a decision tree:

You're a solo founder or two-person team with no academic collaborator. Go SBIR. STTR requires a formal partnership agreement, subaward paperwork, and an intellectual property allocation with the research institution. If you don't already have a partner in mind, don't invent one just to hit an SBIR/STTR ratio.

Your PI is a full-time professor and has no interest in leaving. Go STTR. On SBIR the PI must be primarily employed by the small business, meaning >50% of their working time. If your best scientific mind is a tenured professor, STTR lets them keep their day job and still lead the grant.

You spun out of a university and the tech transfer office already has an option agreement with your company. Go STTR, at least for Phase I. The research institution's continued involvement will strengthen your proposal, and the IP allocation agreement is easier to negotiate when the tech transfer office is already engaged.

Your company does 90% of the work but wants to use a university core facility (mass spec, X-ray, animal model) as a subcontractor. Go SBIR. A subcontract to a university core facility is fine under SBIR — it counts toward the up-to-33% partner limit. You don't need STTR for that.

You're at Phase II and want to accelerate. The rules are the same, but this is where the SBIR PI employment rule bites hardest. On SBIR the PI still must be >50% at the company through Phase II. Many teams shift the PI's role from lead scientist to project director at Phase II. On STTR the PI can stay at the university through Phase II with the company acting as prime.

Your topic is Department of Defense. DOD SBIR is roughly 4x the size of DOD STTR by dollar volume. Topic areas often specify SBIR or STTR — check the solicitation. DOD STTR success rates are similar to SBIR but the topic count is much smaller. If DOD is your target agency, SBIR gives you more shots.

Your topic is NIH. NIH is where STTR really shines. About 15% of NIH's R&D small business dollars go through STTR, and the culture there is comfortable with academic-industry collaborations. If your project needs an academic clinical partner, NIH STTR is often easier to win than NIH SBIR for the same idea.

Phase I, II, III — What Each Actually Funds

Both programs use the same three-phase structure. The differences are only in the eligibility rules above.

Phase I funds the answer to the question: "Is this technically feasible?" Reviewers want a clean, credible experimental plan that will produce a yes/no answer within 6-12 months. Phase I is not for full development. Common Phase I failures are proposals that try to do Phase II work at Phase I prices — reviewers see this immediately.

Typical Phase I awards:

• NIH: up to $300K, 6-12 months
• NSF: $305K, 6-12 months
• DOD: varies by service, typically $100K-$300K, 6 months
• DOE: up to $200K, 6-12 months
• NASA: $150K, 6 months
• USDA: up to $175K, 8 months

Phase II funds actual development. You need to have completed Phase I to be eligible at most agencies (a few — notably DOD Direct-to-Phase-II — allow you to skip Phase I if you can prove feasibility from prior work). Phase II awards run $750K-$2M and last about 24 months. Phase II is where products get built, prototypes get validated, and pilot manufacturing happens.

Typical Phase II awards:

• NIH: up to $2M, 24 months
• NSF: $1M, 24 months
• DOD: typically $1M-$1.7M, 24 months (some services go higher)
• DOE: up to $1.6M, 24 months
• NASA: $850K, 24 months

Phase III funds commercialization. The federal government does not set aside Phase III funding — you're expected to find private capital, revenue, or non-SBIR federal contracts to carry the tech into market. But: any agency can issue a sole-source Phase III contract to a Phase II winner without going back to competition. For dual-use technologies, DOD Phase III contracts often dwarf the Phase I and II awards combined. This is the exit ramp SBIR/STTR is designed to enable.

The 11 Federal Agencies That Run SBIR

Not all agencies run both programs. Here's the actual landscape.

DOD — Department of Defense. The biggest SBIR/STTR spender at roughly $1.8B per year across the services (Army, Navy, Air Force, Space Force, DARPA, MDA, DTRA, and joint offices). Topics are highly specific. Award sizes vary — DARPA is the notable outlier, sometimes offering Phase I awards up to $1M. Runs both SBIR and STTR.

HHS / NIH — National Institutes of Health. About $1.2B per year, spread across the 27 institutes and centers. NIH is the most academic-friendly agency and runs the largest STTR share by percentage. Award sizes are the largest at Phase II ($2M). NIH also has Direct-to-Phase-II and Fast-Track (Phase I + II combined) options. Runs both.

NSF — National Science Foundation. About $200M per year through the America's Seed Fund program. NSF is broad-scope — physical sciences, engineering, computer science, biotech, education tech, energy. Award sizes are $305K (Phase I) and $1M (Phase II). Reviewer culture emphasizes commercialization and market fit heavily. Runs both.

DOE — Department of Energy. About $250M per year, focused on clean energy, grid, nuclear, materials, fusion, and manufacturing. Topics are narrow and technical. Award sizes are $200K (Phase I) and $1.6M (Phase II). Runs both.

NASA. About $200M per year, focused on space, aeronautics, and Earth observation. Awards are smaller than the average at Phase I ($150K) but Phase II is competitive at $850K. Runs both.

USDA — Department of Agriculture. About $30M per year, focused on rural development, food science, forestry, aquaculture, and agricultural biotech. Award sizes are $175K (Phase I) and $650K (Phase II). Runs SBIR only.

EPA — Environmental Protection Agency. About $6M per year, focused on environmental sensing, air/water quality, waste management, and sustainable manufacturing. Award sizes are $100K (Phase I) and $400K (Phase II). Runs SBIR only.

DHS — Department of Homeland Security. About $15M per year, focused on border security, cyber, critical infrastructure, first responder tech. Award sizes are $150K (Phase I) and $1M (Phase II). Runs SBIR only.

DOT — Department of Transportation. About $10M per year, focused on infrastructure, vehicle safety, aviation, transit. Award sizes are $200K (Phase I) and $1.4M (Phase II). Runs SBIR only.

ED — Department of Education. About $9M per year, focused on education tech, assessment, special education. Award sizes are $250K (Phase I) and $1M (Phase II). Runs SBIR only.

DOC — Department of Commerce. About $12M per year via NOAA (ocean, atmosphere, fisheries) and NIST (measurement, standards, manufacturing). Award sizes vary. Runs SBIR only.

Realistic Success Rates

Nobody publishes clean apples-to-apples success rate data, but the consensus numbers from the SBA's annual report and each agency's public dashboards look roughly like this:

• SBIR Phase I overall: 15-20% (weighted average across agencies)
• NIH SBIR Phase I: 14-17%
• NSF SBIR Phase I: 8-12% (NSF is the most competitive by success rate)
• DOD SBIR Phase I: 20-30% (higher because DOD posts specific narrow topics)
• DOE SBIR Phase I: 15-20%
• NASA SBIR Phase I: 15-20%
• Small agencies (USDA, EPA, DOT, ED): 25-40%

STTR success rates are typically within 2-3 percentage points of the same agency's SBIR rate.

Phase II win rate for Phase I winners is much better — usually 40-60% depending on agency. That's why Phase I is called the "gatekeeper." Once you're inside the program, the second win is meaningfully easier than the first.

The honest read: your realistic first-application success rate is probably in the 10-15% range unless you're a strong technical fit for a narrow topic. Plan on writing 3-5 applications before your first win. This is not a knock on your idea — it's just the base rate.

Getting Started This Week

If you're brand new to SBIR/STTR and want to move in the next seven days:

1. Register for a UEI on SAM.gov. Free. Takes 3-6 weeks for federal validation. Do this before anything else, because if you miss this you can't submit even if you finish writing.
2. Pick one agency and one topic. Don't spread across three. Read every open topic at your target agency (DOD SBIR-STTR.mil, NIH's SBIR/STTR page, NSF's America's Seed Fund) and pick the single best fit.
3. Read three past winners in your topic area. NIH RePORTER has full public abstracts. DOD SBIR has the STTR/SBIR success stories page. NSF publishes past awardees. Read the same topic, three winners, before you write a paragraph.
4. Draft a two-page technical concept before you touch the full application. Send it to the agency's SBIR program manager as a "concept check" email. Most agencies respond, and their feedback saves you from writing 25 pages against the wrong topic.

If SBIR is your target and you'd rather start with something less competitive, our complete federal grants guide covers USDA, MBDA, and SBA competitions that many first-time founders win before ever touching SBIR.

Where Windfall Fits

Windfall matches you to grants you actually qualify for — including SBIR and STTR topics matched to your industry, stage, and technical scope. You give Windfall a description of your company and project once; it surfaces the specific open topics across all 11 SBIR agencies (and STTR at the five that participate) that fit. Then, if you want, it drafts the first pass of your technical narrative against the agency's review criteria. Get started free.

FAQ

Which is easier to win, SBIR or STTR? Success rates are similar (within 2-3 percentage points at the same agency). What matters more is fit — a project that genuinely needs an academic partner will usually be more competitive as STTR because the reviewers can tell the partnership is real.

Can I convert a Phase I SBIR to a Phase II STTR? No. You must continue in the program you started in. Phase II SBIR follows Phase I SBIR, Phase II STTR follows Phase I STTR.

Does the PI have to be a US citizen? No. The PI must be legally able to work in the US, and there may be classification restrictions on some DOD topics that require US citizens. But there's no blanket citizenship rule.

Can my small business be part of a larger corporation? Generally no. SBIR/STTR requires the applicant to be a for-profit small business, at least 51% directly owned and controlled by US citizens or permanent residents (or by other small businesses that themselves meet this test), with fewer than 500 employees. There are narrow venture capital exceptions at NIH, NSF, and DOE for majority VC-owned companies.

Do I keep the IP? Yes. Under SBIR, the company owns the IP developed under the award. Under STTR, the IP allocation is negotiated between the company and research partner in writing before submission — but almost always the company retains commercial rights.

How much of my time will an SBIR application take? Phase I applications typically take 60-120 hours of principal investigator time. NIH is usually the longest. Add another 20-40 hours for budget, letters of support, and administrative forms. If you've never applied before, budget the high end.

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