How many letters does the top answer for “of or relating to the making of maps or charts” have?

The most common answer is cartographic (12 letters).

Crossword clue: of or relating to the making of maps or charts

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

cartographic 12 letters wn-def

of or relating to the making of maps or charts

cartographical 14 letters wn-def

of or relating to the making of maps or charts

the making of maps and charts 75% similar → cartography, mapmaking