fencepost problem
Proposed by a contributor, not yet supported by evidence.
Meaning · English
An off-by-one error due to incorrect counting of boundaries
Literally: a problem with fence posts
Where it’s used:
Used
Widespread English
Examples
The programmer fell victim to the fencepost problem when calculating the number of sections
AI-drafted example auto-approved by rule (illustrative, not a corpus attestation)
Sources & notes
Listed in Wiktionary’s “English idioms” category (retrieved 2026-07-29); definition pending editorial review. Definition drafted by AI (@cf/meta/llama-3.3-70b-instruct-fp8-fast) and auto-approved by rule on 2026-07-30; pending editor spot-check.
Common questions
What does “fencepost problem” mean?
An off-by-one error due to incorrect counting of boundaries Literally: a problem with fence posts
Is “fencepost problem” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.