Castle Biosciences, Inc.

CSTL

HealthcareMedical - Diagnostics & ResearchNASDAQ

$19.83

Market Cap: $601.44M

Castle Biosciences, Inc. (CSTL) Valuation Summary

Updated May 11, 2026 03:41

Model	Range	Fair Value	Upside
▸ Discounted Cash Flow
Revenue DCF 5Y	$2.32 – $54.14	$17.83	-10.1%
Revenue DCF 10Y	$4.76 – $107.94	$34.48	+73.9%
▸ Trading Multiples
EV/Revenue	$11.07 – $70.79	$26.61	+34.2%

Valuation History

DCF Analysis

Castle Biosciences, Inc. (CSTL) Revenue DCF (5Y)

REVENUE DCF FAIR VALUE

$34.48

Market Price

$19.83

Upside / Downside

+73.9%

Verdict

Undervalued

Using a Revenue DCF model with operating margin convergence from -12.4% to a target of 13.2% over 5 years, discounted at a WACC of 8.2%, Castle Biosciences, Inc. (CSTL) has an intrinsic value of $34.48 per share (range: $4.76 – $107.94).

Key Assumptions

Current Operating Margin

-12.4%

Target Operating Margin

13.2%

WACC

8.2%

Terminal Growth Rate

3.0%

Historical CapEx/Rev

6.6%

Target CapEx/Rev

10.1%

D&A/Revenue

6.7%

Tax Rate

15.4%

Operating margin fades linearly from the current level to the industry target over the 5-year projection. CapEx intensity fades from the historical average to a maintenance level (D&A × 1.5). Tax is only applied when operating income is positive (NOL shield).

Margin Convergence Projection

USD in millions. Mid-year discounting convention.

Year	Revenue	Growth	Op Margin	Op Income	NOPAT	D&A	CapEx	ΔNWC	FCFF	PV(FCFF)
2026	352	2.2%	-7.3%	-26	-26	24	(24)	19	-46	-44
2027	393	11.6%	-2.2%	-9	-9	26	(29)	6	-17	-15
2028	435	10.7%	2.9%	13	11	29	(33)	6	0	0
2029	470	8.1%	8.1%	38	32	32	(38)	5	21	16
2030	508	8.1%	13.2%	67	57	34	(42)	6	43	30
2031	660	30.0%	13.2%	87	74	44	(57)	23	37	24
2032	835	26.5%	13.2%	110	93	56	(75)	27	47	28
2033	1,008	20.6%	13.2%	133	112	68	(95)	26	59	33
2034	1,157	14.8%	13.2%	153	129	78	(113)	23	71	37
2035	1,260	8.9%	13.2%	166	141	85	(127)	16	82	39

Enterprise Value Bridge

Sum of PV(FCFF)147

Terminal Value (Gordon Growth at 3.0%)1,633

PV of Terminal Value772

Enterprise Value920

(–) Net Debt-80

Equity Value999

(÷) Shares Outstanding29

Fair Value per Share$34.48

Sensitivity Analysis — WACC × Target Operating Margin

WACC \ Target Op. Margin	7.2%	10.2%	13.2%	16.2%	19.2%
6.2%	$13	$37	$60	$84	$108
7.2%	$9	$27	$44	$62	$79
8.2%	$7	$21	$34	$48	$62
9.2%	$6	$17	$28	$39	$50
10.2%	$5	$14	$23	$32	$42

Current price: $19.83. Green = undervalued, Red = overvalued.

Working Capital Assumption

Net Working Capital is modeled at 15.3% of revenue (historical average of receivables + inventory − payables). Changes in NWC (ΔNWC) are computed year-over-year and subtracted from free cash flow.

Castle Biosciences, Inc. (CSTL) Revenue DCF (5Y)

REVENUE DCF FAIR VALUE

$17.83

Market Price

$19.83

Upside / Downside

-10.1%

Verdict

Overvalued

Key Assumptions

Current Operating Margin

-12.4%

Target Operating Margin

13.2%

WACC

8.2%

Terminal Growth Rate

3.0%

Historical CapEx/Rev

6.6%

Target CapEx/Rev

10.1%

D&A/Revenue

6.7%

Tax Rate

15.4%

Margin Convergence Projection

USD in millions. Mid-year discounting convention.

Year	Revenue	Growth	Op Margin	Op Income	NOPAT	D&A	CapEx	ΔNWC	FCFF	PV(FCFF)
2026	352	2.2%	-7.3%	-26	-26	24	(26)	19	-47	-45
2027	393	11.6%	-2.2%	-9	-9	26	(31)	6	-20	-18
2028	435	10.7%	2.9%	13	11	29	(38)	6	-4	-3
2029	470	8.1%	8.1%	38	32	32	(44)	5	14	11
2030	508	8.1%	13.2%	67	57	34	(51)	6	34	24

Enterprise Value Bridge

Sum of PV(FCFF)-32

Terminal Value (Gordon Growth at 3.0%)668

PV of Terminal Value469

Enterprise Value437

(–) Net Debt-80

Equity Value517

(÷) Shares Outstanding29

Fair Value per Share$17.83

Sensitivity Analysis — WACC × Target Operating Margin

WACC \ Target Op. Margin	7.2%	10.2%	13.2%	16.2%	19.2%
6.2%	$6	$18	$30	$42	$54
7.2%	$5	$14	$23	$32	$40
8.2%	$4	$11	$18	$25	$32
9.2%	$3	$9	$15	$21	$26
10.2%	$2	$7	$12	$17	$22

Current price: $19.83. Green = undervalued, Red = overvalued.

Working Capital Assumption

Net Working Capital is modeled at 15.3% of revenue (historical average of receivables + inventory − payables). Changes in NWC (ΔNWC) are computed year-over-year and subtracted from free cash flow.

Trading Multiples

Fair Value

$26.61

Market Price

$19.83

Upside / Downside

+34.2%

Verdict

Undervalued

Using the industry peer median EV/Revenue multiple (trailing + forward), Castle Biosciences, Inc. (CSTL) has a fair value of $26.61 based on 10 comparable companies in the Medical - Diagnostics & Research industry.

EV/Revenue Valuation — Medical - Diagnostics & Research

USD in millions except Fair Price. Subject company highlighted.

	Mkt Cap ($M)	Trailing EV/Revenue	Forward EV/Revenue
Castle Biosciences, Inc.CSTL	575	1.4x	1.4x
Vir Biotechnology, Inc.VIR	1,495	21.1x	10.5x
CareDx, IncCDNA	1,127	2.8x	3.3x
AMN Healthcare Services, Inc.AMN	1,120	0.7x	0.6x
Geron CorporationGERN	892	5.8x	4.6x
Personalis, Inc.PSNL	532	5.7x	6.2x
Evolent Health, Inc.EVH	477	0.7x	0.5x
Fulgent Genetics, Inc.FLGT	453	1.3x	1.5x
Myriad Genetics, Inc.MYGN	405	0.6x	0.5x
Embecta Corp.EMBC	216	1.3x	1.4x
DarioHealth Corp.DRIO	57	2.8x	2.4x
Industry Median		2.1x	1.9x
(*) Revenue		344	352
= Enterprise Value		708	675
(-) Net Debt		-80	-80
Equity Value		787	755
(/) Outstanding shares		29	29
Fair Price		$27	$26

Selected Fair Value (avg of trailing + forward)

$26.61

+34.2%

Disclaimer: Sweet Value Lab provides estimated intrinsic values for informational purposes only. This is not financial advice. All models rely on assumptions that may not reflect future performance. Always do your own research before making investment decisions.

Model

Range

Fair Value

Upside

▸ Discounted Cash Flow

Revenue DCF 5Y

$2.32 – $54.14

$17.83

-10.1%

Revenue DCF 10Y

$4.76 – $107.94

$34.48

+73.9%

▸ Trading Multiples

EV/Revenue

$11.07 – $70.79

$26.61

+34.2%

DCF Analysis

Castle Biosciences, Inc. (CSTL) Revenue DCF (5Y)

REVENUE DCF FAIR VALUE

$34.48

Market Price

$19.83

Upside / Downside

+73.9%

Verdict

Undervalued

Key Assumptions

Current Operating Margin

-12.4%

Target Operating Margin

13.2%

WACC

8.2%

Terminal Growth Rate

3.0%

Historical CapEx/Rev

6.6%

Target CapEx/Rev

10.1%

D&A/Revenue

6.7%

Tax Rate

15.4%

Margin Convergence Projection

USD in millions. Mid-year discounting convention.

Year	Revenue	Growth	Op Margin	Op Income	NOPAT	D&A	CapEx	ΔNWC	FCFF	PV(FCFF)
2026	352	2.2%	-7.3%	-26	-26	24	(24)	19	-46	-44
2027	393	11.6%	-2.2%	-9	-9	26	(29)	6	-17	-15
2028	435	10.7%	2.9%	13	11	29	(33)	6	0	0
2029	470	8.1%	8.1%	38	32	32	(38)	5	21	16
2030	508	8.1%	13.2%	67	57	34	(42)	6	43	30
2031	660	30.0%	13.2%	87	74	44	(57)	23	37	24
2032	835	26.5%	13.2%	110	93	56	(75)	27	47	28
2033	1,008	20.6%	13.2%	133	112	68	(95)	26	59	33
2034	1,157	14.8%	13.2%	153	129	78	(113)	23	71	37
2035	1,260	8.9%	13.2%	166	141	85	(127)	16	82	39

Enterprise Value Bridge

Sum of PV(FCFF)147

Terminal Value (Gordon Growth at 3.0%)1,633

PV of Terminal Value772

Enterprise Value920

(–) Net Debt-80

Equity Value999

(÷) Shares Outstanding29

Fair Value per Share$34.48

Sensitivity Analysis — WACC × Target Operating Margin

WACC \ Target Op. Margin	7.2%	10.2%	13.2%	16.2%	19.2%
6.2%	$13	$37	$60	$84	$108
7.2%	$9	$27	$44	$62	$79
8.2%	$7	$21	$34	$48	$62
9.2%	$6	$17	$28	$39	$50
10.2%	$5	$14	$23	$32	$42

Current price: $19.83. Green = undervalued, Red = overvalued.

Working Capital Assumption

Net Working Capital is modeled at 15.3% of revenue (historical average of receivables + inventory − payables). Changes in NWC (ΔNWC) are computed year-over-year and subtracted from free cash flow.

Trading Multiples

Fair Value

$26.61

Market Price

$19.83

Upside / Downside

+34.2%

Verdict

Undervalued

EV/Revenue Valuation — Medical - Diagnostics & Research

USD in millions except Fair Price. Subject company highlighted.

	Mkt Cap ($M)	Trailing EV/Revenue	Forward EV/Revenue
Castle Biosciences, Inc.CSTL	575	1.4x	1.4x
Vir Biotechnology, Inc.VIR	1,495	21.1x	10.5x
CareDx, IncCDNA	1,127	2.8x	3.3x
AMN Healthcare Services, Inc.AMN	1,120	0.7x	0.6x
Geron CorporationGERN	892	5.8x	4.6x
Personalis, Inc.PSNL	532	5.7x	6.2x
Evolent Health, Inc.EVH	477	0.7x	0.5x
Fulgent Genetics, Inc.FLGT	453	1.3x	1.5x
Myriad Genetics, Inc.MYGN	405	0.6x	0.5x
Embecta Corp.EMBC	216	1.3x	1.4x
DarioHealth Corp.DRIO	57	2.8x	2.4x
Industry Median		2.1x	1.9x
(*) Revenue		344	352
= Enterprise Value		708	675
(-) Net Debt		-80	-80
Equity Value		787	755
(/) Outstanding shares		29	29
Fair Price		$27	$26

Selected Fair Value (avg of trailing + forward)

$26.61

+34.2%