Q. How many kanji do I need to learn to read Japanese?
A. Japanese is written in a combination of three scripts: hiragana, katakana and kanji, originated from Chinese characters. They were introduced to Japan nearly 2,000 years ago. Several centuries later, hiragana and katakana developed from kanji to express Japanese syllables phonetically.
If you wish to become proficient in reading and writing Japanese, you need to learn kanji. However if you are a beginner, I recommend you learn hiragana and katakana first, then kanji. Japanese schoolchildren also learn hiragana and katakana first. It is possible to write entire Japanese sentences in hiragana. Even after mastering kanji, when you forget or don't know the kanji characters for a word, you can write it in hiragana phonetically.
It is said that some 50,000 kanji exist. However, many kanji are not necessarily used in daily life. The Japanese Ministry of Education designated 1,945 characters as Jooyoo Kanji, which are the most frequently used characters. It would be very helpful to learn all Jooyoo Kanji, but the basic 1,000 characters are sufficient to read about 90% of the kanji used in a newspaper (about 60% with 500 characters). Since children's books use less kanji, they would be a good resource to practice your reading.