http://www.collinsdictionary.com/dictionary/english/half_1 I found this page online which lists the most common words which end in -f and have the plural form -ves. https://howtospell.co.uk/plural-ves-rule

Halves. Put "halfs" into a Google search. There's a reason why Google says, at the top of the responses, "Did you mean halves?"