Klaviyo IPO Presentation Deck

GAAP to Non-GAAP reconciliation Non-GAAP Gross Profit (in thousands) Gross Profit on a GAAP Basis Add: Amortization of Prepaid Marketing Expense Add: Stock-Based Compensation Expense ¹ 2 Add: Restructuring Expense ² Non-GAAP Gross Profit Revenue Gross Margin Year Ended December 31 2021 $205,944 960 $206,904 $290,640 70.9% 2022 $344,723 129 $344,852 $472,748 72.9% Non-GAAP Gross Margin 71.2% ¹ Represents non-cash share-based awards granted. During the years ended December 31, 2022 and 2021, stock-based compensation expense of $1.5 million and $16.7 million, respectively, related to repurchasing and retiring our common stock which was paid in cash, and thus are excluded from the table above. 2 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. 72.9% Six Months Ended June 30 2022 $150,270 80 $150,350 $208,345 72.1% 72.2% 2023 Ⓒ Klaviyo 2023 $246,624 43 1,156 $247,823 $320,674 76.9% 77.3% Confidential 49

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