> For the complete documentation index, see [llms.txt](https://jgoodman8.gitbook.io/iron-data-science-notebook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jgoodman8.gitbook.io/iron-data-science-notebook/ml-datascience/computer-vision/object-detection/metrics/iou.md).

# IoU

Metrics Matter: A deep dive into object detector evaluation ([*Medium*](https://medium.com/@henriquevedoveli/metrics-matter-a-deep-dive-into-object-detection-evaluation-ef01385ec62))

Intersection over Union (IoU), also known as Jaccard’s Index, is calculated by taking the intersection area of two bounding boxes and dividing it by the union area of these boxes.

<figure><img src="https://569842953-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LmjpNbCRLUyGiAxD8kn%2Fuploads%2FTDaAkY12oO7QfOUufDvf%2Fimage.png?alt=media&amp;token=c320060f-41ed-4e61-b24c-b3e2db82cd3a" alt=""><figcaption></figcaption></figure>

It quantifies the degree of overlap between the predicted bounding box and the ground truth bounding box.