wide of the mark

If something is wide of the mark, it is inaccurate or incorrect — мимо, неверно; пальцем в небо; ~ с точностью до наоборот (по контексту)

Example 1: Yesterday's weather forecast for today was rather wide of the mark. It's been a beautiful sunny day, but the forecast said it would be
wet and windy.

Example 2: The manager expected sales to double this year, but his prediction was wide of the mark. They only increased by ten per cent.

[shot in the dark]
[off the mark]
a long way out
[с точностью до наоборот]