How much was 5 shillings in 1800 worth today in dollars?

Five Shillings GBP in 1800 had the purchasing power of about £12.10 GBP today.

Five Shillings GBP in 1800 had the purchasing power of about $19.49 USD today.

NOTE - This historical conversion is the result of many calculations and considerations by a purpose designed program for which I can take no credit. The resulting answer should only be regarded as an approximation.