• Standard Time: IST is 11 hours and 30 minutes ahead of Central Standard Time (CST).
• Daylight Saving Time (DST): During DST, IST is 10 hours and 30 minutes ahead of Central Daylight Time (CDT).

• Standard Time: IST is 10 hours and 30 minutes ahead of Eastern Standard Time (EST).
• Daylight Saving Time (DST): During DST, IST is 9 hours and 30 minutes ahead of Eastern Daylight Time (EDT).

• Standard Time: IST is 12 hours and 30 minutes ahead of Mountain Standard Time (MST).
• Daylight Saving Time (DST): During DST, IST is 11 hours and 30 minutes ahead of Mountain Daylight Time (MDT).

• Standard Time: IST is 13 hours and 30 minutes ahead of Pacific Standard Time (PST).
• Daylight Saving Time (DST): During DST, IST is 12 hours and 30 minutes ahead of Pacific Daylight Time (PDT).

Daylight Saving Time (DST) is the practice of setting clocks forward by one hour during warmer months to extend evening daylight and reduce energy consumption. It begins in the U.S. on the second Sunday in March and ends on the first Sunday in November, with clocks moving forward in spring and back in autumn.