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BillionToOne vs Castle Biosciences: BLLN and CSTL compared
BillionToOne is the larger company: $123M of revenue in its latest quarter (Q3 2026) against $103M for Castle Biosciences (Q3 2026). BillionToOne is growing faster (+47% against +24% a year earlier). BillionToOne is more profitable, with an operating margin of 9.0% against -2.7%.
Where the money goes: BLLN and CSTL
BillionToOne (BLLN) · Q3 2026
BillionToOne, Q3 2026: revenue $123M (+47% year over year), operating margin 9.0%, net earnings $17.4M, operating cash flow $12.5M. The chart follows the revenue to costs, profit and cash.
Castle Biosciences (CSTL) · Q3 2026
Castle Biosciences, Q3 2026: revenue $103M (+24% year over year), operating margin -2.7%, net loss $4.1M, operating cash flow $19.7M. The chart follows the revenue to costs, profit and cash.
| BillionToOne (BLLN) | Castle Biosciences (CSTL) | |
|---|---|---|
| Latest quarter | Q3 2026 | Q3 2026 |
| Revenue | $123M | $103M |
| Revenue growth, Y/Y | +47% | +24% |
| Gross margin | 70.9% | — |
| Operating margin | 9.0% | -2.7% |
| Net earnings | $17.4M | −$4.1M |
| Net margin | 14.1% | -4.0% |
| Operating cash flow | $12.5M | $19.7M |
| Free cash flow | $8.6M | $12.2M |
Where the revenue comes from
BillionToOne
- Prenatal: $104M (85%)
- Oncology: $17.1M (14%)
- Clinical trial support and other services: $1.6M (1%)
Castle Biosciences
- Non-Dermatologic: $55.0M (53%)
- Dermatologic: $47.9M (47%)
Questions
Which is bigger, BillionToOne or Castle Biosciences?
BillionToOne is the larger company: $123M of revenue in its latest quarter (Q3 2026) against $103M for Castle Biosciences (Q3 2026).
Is BillionToOne or Castle Biosciences growing faster?
BillionToOne is growing faster (+47% against +24% a year earlier).
Which is more profitable, BillionToOne or Castle Biosciences?
BillionToOne is more profitable, with an operating margin of 9.0% against -2.7%.
More: BillionToOne earnings · how BillionToOne makes money · Castle Biosciences earnings · how Castle Biosciences makes money
From the companies' latest 10-Q, 10-K or earnings release (10-Q filed Nov 4, 2026; 10-Q filed Nov 5, 2026). Fiscal quarters can end on different dates. Not investment advice.