In China, electric vehicle (EV) fast-charging power has quadrupled in the past five years, progressing toward 10-minute ultrafast charging. This rapid increase raises concerns about the impact on the power grid including increased peak power demand and the need for substantial upgrades to power infrastructure. Here, we introduce an integrated model to assess fast and ultrafast charging impacts for representative charging stations in China, combining real-world charging patterns and detailed station optimization models. We find that larger stations with 12 or more chargers experience modest peak power increases of less than 30% when fast-charging power is doubled, primarily because shorter charging sessions are less likely to overlap. For more typical stations (e.g., 8–9 chargers and 120 kW·charger⁻¹), upgrading chargers to 350–550 kW while allowing managed dynamic waiting strategies (of ∼1 minute) can reduce overall charging times to ∼9 minutes. At stations, deploying battery storage and/or expanding transformers can help manage future increases in station loads, yet the primary device cost of the former is ∼4 times higher than that of the latter. Our results offer insights for charging infrastructure planning, EV–grid interactions, and associated policymaking.