Earnings per Share (Tables)

12 Months Ended

Sep. 27, 2020

Earnings Per Share [Abstract]

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

The following table sets forth the number of weighted-average shares used to compute basic and diluted EPS:

	Fiscal Year Ended
	September 27, 2020		September 29, 2019		September 30, 2018
	(in thousands, except per share data)
Net income attributable to Tetra Tech	$	173,859	$	158,668	$	136,883
Weighted-average common shares outstanding – basic	54,235		54,986		55,670
Effect of diluted stock options and unvested restricted stock	787		950		928
Weighted-average common stock outstanding – diluted	55,022		55,936		56,598
Earnings per share attributable to Tetra Tech:
Basic	$	3.21	$	2.89	$	2.46
Diluted	$	3.16	$	2.84	$	2.42