Earnings per Share ("EPS") (Tables)

6 Months Ended

Mar. 30, 2025

Earnings Per Share [Abstract]

Schedule of number of weighted-average shares used to compute basic and diluted EPS

The following table presents the number of weighted-average shares used to compute basic and diluted EPS (in thousands, except per share data):

	Three Months Ended				Six Months Ended
	March 30, 2025		March 31, 2024		March 30, 2025		March 31, 2024
Net income attributable to Tetra Tech	$	5,388	$	76,446	$	6,135	$	151,418
Weighted-average common shares outstanding – basic	265,728		267,420		266,819		267,095
Effect of dilutive stock options and unvested restricted stock	1,711		1,955		1,936		2,030
Shares issuable assuming conversion of convertible notes	—		—		936		$	—
Weighted-average common shares outstanding – diluted	267,439		269,375		269,691		269,125
Earnings per share attributable to Tetra Tech:
Basic	$	0.02	$	0.29	$	0.02	$	0.57
Diluted	$	0.02	$	0.28	$	0.02	$	0.56