We examine the sustainability of consumption choices using unique data from a FinTech app tracking spending and emissions. Using a randomized encouragement design, we show that carbon calculator services that provide transaction-level information on emissions do not change users’ behavior. Instead, carbon-offsetting services, though less popular, are effective in reducing emissions. A survey of app users suggests the carbon calculator’s ineffectiveness stems from users not prioritizing climate change over other economic issues. Limited attention instead explains the low adoption of carbon offsetting. These findings highlight the challenges and opportunities of sustainability tools that have been increasingly adopted by financial institutions.