Shire-reckoning

The system of reckoning dates unique to the Hobbits of the Shire, based on the founding of that land in T.A. 1601. The Shire-hobbits reckoned this as year 1. So, years of the Third Age can be converted to Shire-years by subtracting 1600 (e.g. the Downfall of Barad-dûr occurred in III 3019, but in the Shire this was counted as the year 1419).

The Shire-folk took no account of the change of Age in III 3021. While the other peoples of Middle-earth considered this to be the first year of the Fourth Age, in the Shire it was simply 1421.