失之毫厘，差以千里
shī​zhī​háo​lí​chà​yǐ​qiān​lǐ

a tiny lapse can lead to a huge mistake

  1. 失 shī verb
    to miss
    to miss; to let slip; to fail to seize something like an opportunity or chance
  2. 之 zhī pronoun
    it
    Used only in the object position to refer to a person or thing already mentioned, meaning "him", "her", "it", or "them".
  3. 毫厘 毫釐 háo​lí
    an iota
    the least bit; an extremely small amount
  4. ， chà
    non-Chinese
  5. 差 chà verb
    to lack
    to differ by; to be short of; to lack; to be missing
  6. 以 yǐ preposition
    by means of
    to use; by means of; with; using the tool or method introduced
  7. 千里 qiān​lǐ
    a thousand li
    one thousand 里 lǐ; approximately 500 kilometers; used metaphorically to mean a very long distance