"How many words do I need for HSK 4?" is one of the most-searched HSK questions — and the answer changed with HSK 3.0. This is your reference table for both standards, plus how to actually get the words into long-term memory.
HSK 3.0 vocabulary and characters, per band
The HSK 3.0 standard (国际中文教育中文水平等级标准) is explicit about both words and characters. These are cumulative totals: