How many days were "lost" when the calendar changed in 1752?
Quick Answer: When the calendar switched in 1752, 11 days were lost. In Britain and its colonies, September 2, 1752, was followed directly by September 14, 1752, skipping those 11 days to correct the calendar drift.
The change happened because Britain moved from the Julian calendar to the Gregorian calendar. The Julian calendar had slowly fallen out of sync with the solar year, causing seasons and dates to drift. To fix this, 11 days were removed in 1752.
This adjustment aligned the calendar with the solar year and with much of Europe, which had already made the switch. So people went to bed on September 2 and woke up on September 14 that year!