Wizard Currency Converter (Galleons, Sickles & Knuts from the Harry Potter books)

Understanding the wizard currency converter — concept and principle

This fan calculator adds up Galleons, Sickles and Knuts, the coins of the wizarding world in the Harry Potter books, tidies them into the fewest coins and converts them to and from real money at an exchange rate you choose. It is for fun, for fan games, quizzes and party props.

How it is calculated

1 Galleon = 17 Sickles; 1 Sickle = 29 Knuts; so 1 Galleon = 17 × 29 = 493 Knuts

Total Knuts = Galleons × 493 + Sickles × 29 + Knuts

Tidying: Galleons = ⌊total ÷ 493⌋, then Sickles = ⌊remainder ÷ 29⌋, and the rest are Knuts

Real-money value = total Knuts ÷ 493 × your rate per Galleon

• Converting real money into coins rounds to the nearest Knut.

The principle

Unlike most real currencies, which use powers of ten, the wizarding coins use the odd ratios 17 and 29, so mental arithmetic is awkward. The cleanest method is the same one used for hours and minutes: turn everything into the smallest unit, then regroup with division and remainders. The books never give an official exchange rate, and fan estimates vary widely, so the real-money value depends entirely on the rate you enter; the default of 5 per Galleon is only an example.

Worked example

Default inputs: 3 Galleons, 20 Sickles, 40 Knuts, rate $5 per Galleon, convert $20.

1. Total = 3 × 493 + 20 × 29 + 40 = 1,479 + 580 + 40 = 2,099 Knuts.
2. Galleons = ⌊2,099 ÷ 493⌋ = 4, remainder 127; Sickles = ⌊127 ÷ 29⌋ = 4, remainder 11.
3. Tidied: 4 Galleons, 4 Sickles, 11 Knuts.
4. In Galleons: 2,099 ÷ 493 = 4.258; in Sickles: 2,099 ÷ 29 = 72.38; value = 4.258 × 5 = $21.29.
5. $20 ÷ 5 × 493 = 1,972 Knuts = 4 Galleons, 0 Sickles, 0 Knuts.

How to read the result

The tidied line is how you would pay with the fewest coins. The real-money value is only as meaningful as the rate; change it to see how fan estimates differ.

Common mistakes

• Assuming 100 Knuts to a Sickle, or 20 Sickles to a Galleon.
• Converting directly between Galleons and Knuts with 29 instead of 493.
• Treating the exchange rate as official.
• Leaving more than 28 Knuts or 16 Sickles untidied.

Frequently asked questions

How many Knuts are in a Galleon?

493 (17 Sickles × 29 Knuts).

Where do the coin ratios come from?

From the first book, in the chapter "Diagon Alley".

Is there an official Galleon to pound or dollar rate?

Not in the books. Fan estimates vary widely, so the calculator lets you set your own.

Sources: J. K. Rowling, Harry Potter and the Philosopher's Stone (1997), chapter 5 "Diagon Alley"