diff --git a/src/batdetect2/evaluate/affinity.py b/src/batdetect2/evaluate/affinity.py
index 1ffa868..c8ff253 100644
--- a/src/batdetect2/evaluate/affinity.py
+++ b/src/batdetect2/evaluate/affinity.py
@@ -3,6 +3,7 @@ from typing import Annotated, Literal, Optional, Union
 from pydantic import Field
 from soundevent import data
 from soundevent.evaluation import compute_affinity
+from soundevent.geometry import compute_interval_overlap
 
 from batdetect2.core.configs import BaseConfig
 from batdetect2.core.registries import Registry
@@ -93,9 +94,11 @@ def compute_interval_iou(
     end_time1 += time_buffer
     end_time2 += time_buffer
 
-    intersection = max(
-        0, min(end_time1, end_time2) - max(start_time1, start_time2)
+    intersection = compute_interval_overlap(
+        (start_time1, end_time1),
+        (start_time2, end_time2),
     )
+
     union = (
         (end_time1 - start_time1) + (end_time2 - start_time2) - intersection
     )
@@ -106,6 +109,86 @@ def compute_interval_iou(
     return intersection / union
 
 
+class BBoxIOUConfig(BaseConfig):
+    name: Literal["bbox_iou"] = "bbox_iou"
+    time_buffer: float = 0.01
+    freq_buffer: float = 1000
+
+
+class BBoxIOU(AffinityFunction):
+    def __init__(self, time_buffer: float, freq_buffer: float):
+        self.time_buffer = time_buffer
+        self.freq_buffer = freq_buffer
+
+    def __call__(self, geometry1: data.Geometry, geometry2: data.Geometry):
+        if not isinstance(geometry1, data.BoundingBox):
+            raise TypeError(
+                f"Expected geometry1 to be a BoundingBox, got {type(geometry1)}"
+            )
+
+        if not isinstance(geometry2, data.BoundingBox):
+            raise TypeError(
+                f"Expected geometry2 to be a BoundingBox, got {type(geometry2)}"
+            )
+        return bbox_iou(
+            geometry1,
+            geometry2,
+            time_buffer=self.time_buffer,
+            freq_buffer=self.freq_buffer,
+        )
+
+    @affinity_functions.register(BBoxIOUConfig)
+    @staticmethod
+    def from_config(config: BBoxIOUConfig):
+        return BBoxIOU(
+            time_buffer=config.time_buffer,
+            freq_buffer=config.freq_buffer,
+        )
+
+
+def bbox_iou(
+    geometry1: data.BoundingBox,
+    geometry2: data.BoundingBox,
+    time_buffer: float = 0.01,
+    freq_buffer: float = 1000,
+) -> float:
+    start_time1, low_freq1, end_time1, high_freq1 = geometry1.coordinates
+    start_time2, low_freq2, end_time2, high_freq2 = geometry2.coordinates
+
+    start_time1 -= time_buffer
+    start_time2 -= time_buffer
+    end_time1 += time_buffer
+    end_time2 += time_buffer
+
+    low_freq1 -= freq_buffer
+    low_freq2 -= freq_buffer
+    high_freq1 += freq_buffer
+    high_freq2 += freq_buffer
+
+    time_intersection = compute_interval_overlap(
+        (start_time1, end_time1),
+        (start_time2, end_time2),
+    )
+
+    freq_intersection = max(
+        0,
+        min(high_freq1, high_freq2) - max(low_freq1, low_freq2),
+    )
+
+    intersection = time_intersection * freq_intersection
+
+    if intersection == 0:
+        return 0
+
+    union = (
+        (end_time1 - start_time1) * (high_freq1 - low_freq1)
+        + (end_time2 - start_time2) * (high_freq2 - low_freq2)
+        - intersection
+    )
+
+    return intersection / union
+
+
 class GeometricIOUConfig(BaseConfig):
     name: Literal["geometric_iou"] = "geometric_iou"
     time_buffer: float = 0.01
@@ -133,6 +216,7 @@ AffinityConfig = Annotated[
     Union[
         TimeAffinityConfig,
         IntervalIOUConfig,
+        BBoxIOUConfig,
         GeometricIOUConfig,
     ],
     Field(discriminator="name"),