Burn Rate for Biotech Startups: Modeling Cash to Approval

Biotech burn rates are not like software. They are an order of magnitude bigger, the timelines are longer, and the calculation needs to think in terms of trial milestones rather than just months. But the math is the same — bank divided by burn equals time left.

Why biotech burn is unique

Software startups can pivot. They can cut features, change positioning, redirect engineering work. Biotech cannot. Once a clinical trial is enrolled, you cannot pause it for a quarter to save cash. The work and the spending must continue to the next milestone.

This makes biotech runway calculations less about "how long can we survive in months" and more about "do we have enough to reach the next data readout, and then enough buffer to raise on it?"

Biotech burn rate by stage

Stage	Typical monthly burn	Cash needed to reach next stage
Discovery / preclinical	$200K-$800K	$5M-$15M
IND-enabling	$400K-$1.2M	$10M-$30M
Phase 1	$700K-$2M	$15M-$50M
Phase 2	$1M-$3M	$50M-$200M
Phase 3	$2M-$5M	$200M-$800M
NDA/BLA review	$1.5M-$4M	$50M-$150M
Commercial launch	$5M-$20M+	Variable

These are wide ranges because therapeutic area, geography, and trial design all influence cost. Oncology and rare disease tend to be on the higher end. CNS and dermatology can be lower.

The milestone-runway model

Most biotech CFOs build their runway model around catalysts, not calendar months:

Milestone	Months from now	Cash needed
Phase 2 enrollment complete	6 months	$8M
Phase 2 interim readout	12 months	$15M
Phase 2 final readout	18 months	$24M
Buffer to fundraise on data	+6 months	+$8M
Total cash to safely reach raise	24 months	$32M

If the company has $40M in cash, they have $8M of buffer above the safe threshold. If they have $25M, they need to raise sooner — likely on Phase 2 interim data, which is risky.

Why "[company] cash runway" is searched so often

Public biotech investors track cash runway religiously because it predicts dilution risk. A biotech with 8 months of runway is almost certain to raise within 6 months, which means dilution is coming. The market often discounts the stock in advance.

This is why search queries like "moderna cash runway", "crispr therapeutics cash runway", and "biotech cash runway" generate constant traffic — investors want to know the cash position of every public biotech.

What burn looks like in a biotech P&L

Category	% of monthly burn	Notes
R&D personnel	35-50%	Scientists, clinicians, regulatory
Clinical trial costs (CROs)	25-40%	Largest single line at trial stage
CMC / manufacturing	5-15%	Drug substance, GMP supply
G&A	10-20%	Legal, finance, IR, exec team
Lab supplies / overhead	5-10%	Consumables, equipment
Other (insurance, office)	3-5%	Standard

R&D and clinical trial costs together usually account for 60-80% of biotech burn. Cutting them is not really an option — it would slow the program. So extension tactics tend to be capital strategy (non-dilutive grants, partnerships) rather than expense reduction.

Burn extension tactics for biotech

1. Grant funding: NIH, BARDA, DoD, ARPA-H, and disease-specific foundations all fund early biotech. Non-dilutive but slow.
2. Pharma partnerships: Out-license a region, indication, or backup molecule for upfront cash and milestones. Common at Phase 1-2.
3. Strategic investments: Pharma corporate VCs often invest at higher valuations than financial VCs because they have strategic interest.
4. Convertible notes / SAFEs: Bridge between rounds without setting a new valuation. Useful when waiting for a data readout to set the next round price.
5. PIPE deals (for public): Private investment in public equity. Faster than a follow-on offering but typically at a discount.
6. Royalty financing: Sell future royalties on an approved or near-approved product for cash today. Late-stage only.

Tracking burn at biotech scale

Biotech CFOs typically build a quarterly burn forecast in a spreadsheet that maps personnel, CRO, CMC, and G&A across the trial timeline. The burn rate calculator can be used for the high-level monthly snapshot — bank balance, monthly burn (gross since most biotech is pre-revenue), runway in months. It will not replace a full operating model but it is a fast sanity check before board prep.

For biotech, the most important conversation is not "what is your burn" but "what is your cash to next data and your buffer to raise on it." The burn rate is just one input.