誤算

1. Origins, structure, and basic meaning

• Structure: 誤算 is read as ごさん and is a noun for a calculation or expectation that proves wrong, including a mistaken strategic judgment.
• Basic usage: Calling fewer-than-expected guests the biggest miscalculation appears in 最大の誤算だ, while having an error in an estimate appears in 見積もりに誤算がある.

2. Common pitfalls and similar expressions

• Used for figures and plans
  • It covers both numerical errors and an assumption or expectation in a plan that turns out to be wrong.
• Difference from 計算違い
  • Compared with a straightforward calculation error, this term also covers a strategic or predictive mistake.