In the Harry Potter books, seventeen sickles make one Galleon.
Wizarding Britain uses three main coins: Knuts, Sickles, and Galleons. The conversion stated in the books is twenty-nine Knuts to one Sickle and seventeen Sickles to one Galleon. These values create a fictional currency system rather than a direct copy of modern British money.
The coins appear throughout the series when characters buy school supplies, food, joke-shop products, and other magical goods. Harry’s inherited wealth allows him to shop at Diagon Alley without the financial limitations faced by the Weasley family, while prices help show differences in their circumstances.
The number is easy to confuse with the twelve-pence-to-one-shilling system used in pre-decimal British currency, but seventeen is the specific Harry Potter conversion. The books do not establish a fixed exchange rate between wizarding coins and Muggle pounds, so real-world currency comparisons are approximate rather than canonical.