Klaviyo IPO Presentation Deck

GAAP to Non-GAAP reconciliation (cont'd) Non-GAAP Operating (Loss) Income (in thousands) Operating Loss on a GAAP Basis Add: Amortization of Prepaid Marketing Expense Add: Stock-Based Compensation Expense 1,2 Add: Restructuring ³ 3 Non-GAAP Operating Income (Loss) Revenue Operating Loss Margin Non-GAAP Operating Margin Q1'21 14,503 Q2'21 (33.5%) Q3'21 3,025 12,064 ($19,513) ($8,695) ($20,363) ($30,662) ($12,979) ($12,317) ($25,663) (13.0%) (8.6%) (8.5%) Q4'21 (26.8%) (10.9%) 5,656 Q1'22 (34.2%) (27.9%) Q2'22 5,176 Q3'22 547 8,816 522 ¹ Represents non-cash share-based awards granted. Stock-based compensation expense of $1.5 million for the quarter ending December 31, 2022 related to the cancellation of an executive's unvested RSUS outstanding for which the service-based vesting condition was satisfied but the liquidity-based vesting condition was not, which was paid in cash, and thus is excluded from the table above. This is included within general and administrative expense. Q4'22 2 Represents non-cash share-based awards granted. Stock-based compensation expense of $16.7 million related to repurchasing and retiring our common stock was paid in cash, thus excluded from the table above. 3 Represents restructuring costs incurred in connection with a reduction in the Company's workforce announced in March 2023. During the period ended March 31, 2023, stock-based compensation expense of approximately $0.5 million related to the reduction in workforce is excluded from restructuring expense and included in stock-based compensation from the table above. ($4,077) 557 $20,775 ($5,010) ($5,670) ($8,299) ($25,006) ($7,803) ($11,770) ($16,325) $9,704 $23,291 $99,322 $109,023 $119,168 $145,235 $156,088 $164,586 $58,271 $66,949 $75,876 $89,544 (13.1%) (11.3%) (21.5%) (2.8%) (7.9%) (10.8%) (13.7%) Q1'23 13,224 13,224 $878 6.7% 1,823 7,366 0.6% 14.9% 2023 Ⓒ Klaviyo Q2'23 $7,032 Confidential 13,224 519 4.3% 12.6% 59

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