How many wicks, and where do they go?
One wick in a wide jar tunnels down the middle, while extra wicks burn hot and sooty. This page takes two figures, the inside diameter of the jar and the melt pool diameter of a single wick, and finds the fewest wicks that melt the surface out to the wall, plus where to set them.
The layout rule: each pool reaches the wall, so the wicks sit on a ring whose radius is half of the inside diameter minus the pool diameter, and neighboring pools must touch or slightly overlap. Starting from one wick, the page adds wicks; for each count it tries both all wicks on the ring and the ring plus one center wick, keeps whichever leaves less unmelted area, and stops when the area left outside every pool is 25% of the surface or less. A single wick has to do better, 10% or less, because a rim left by one wick is what causes tunneling. That leftover area is estimated by sampling the surface and shown in square inches, never rounded down to zero. For example, with a 3 in pool this gives 1 wick up to 3.1 in, 2 wicks for 3.2 to 4.2 in, 3 wicks for 4.3 to 5.5 in and 4 wicks for 5.6 to 6.7 in. At higher counts such as 7, the page picks 6 around plus 1 in the center so the middle is not left unmelted.
Wick series numbers are not covered, because each maker numbers wicks on its own scale and no official standard exists; enter the maker's published melt pool figure instead. Several wicks heat each other, so real pools often grow a little wider than the single-wick test value, and wax type or fragrance load also change burn width. Confirm the result with a test burn of at least three to four hours.
Frequently Asked Questions
Series numbering and the pool width per number are each maker's own scale with no official standard, so the page asks for the published melt pool diameter instead.
Round pools cannot tile a round jar, so small pockets remain between neighboring pools and the wall. Heat from the joined liquid wax usually melts them; the page shows their size so you can compare options. A larger wick shrinks them.
The count follows the pool size you enter. With a 2 in pool a 5.7 in jar needs 7 wicks (6 around plus 1 in the center), while a 3 in pool needs 4 and a 3.5 in pool needs 3. In wide jars a larger wick with fewer pieces is usually easier to burn evenly.