Understanding End-to-End Detection in Ultralytics YOLO26

Introduction

If you're upgrading to YOLO26 from an earlier model like YOLOv8 or YOLO11, one of the biggest changes you'll notice is the removal of Non-Maximum Suppression (NMS). Traditional YOLO models produce thousands of overlapping predictions that need a separate NMS post-processing step to filter down to final detections. This adds latency, complicates export graphs, and can behave inconsistently across different hardware platforms.

YOLO26 takes a different approach. It outputs final detections directly from the model — no external filtering required. This is known as end-to-end object detection, and it's enabled by default in all YOLO26 models. The result is a simpler deployment pipeline, lower latency, and up to 43% faster inference on CPUs.

This guide walks you through what changed, whether you need to update your code, which export formats support end-to-end inference, and how to migrate smoothly from older YOLO models.

For a deeper look at the motivation behind this architectural shift, see the Ultralytics blog post on why YOLO26 removes NMS.

How End-to-End Detection Works

YOLO26 uses a dual-head architecture during training. Both heads share the same backbone and neck, but produce outputs in different ways:

The shapes above are for detection. Other tasks extend the one-to-one output with additional data per detection:

During training, both heads run simultaneously — the one-to-many head provides a richer learning signal, while the one-to-one head learns to produce clean, non-overlapping predictions. During inference and export, only the one-to-one head is active by default, producing up to 300 detections per image in the format [x1, y1, x2, y2, confidence, class_id].

When you call model.fuse(), it folds Conv + BatchNorm layers for faster inference and, on end-to-end models, also removes the one-to-many head — reducing model size and FLOPs. For more details on the dual-head architecture, see the YOLO26 model page.

Do I Need to Change My Code?

Using the Ultralytics Python API or CLI

No changes needed. If you use the standard Ultralytics Python API or CLI, everything works automatically — prediction, validation, and export all handle end-to-end models out of the box.

from ultralytics import YOLO

# Load a YOLO26 model
model = YOLO("yolo26n.pt")

# Predict — no NMS step, no code changes
results = model.predict("image.jpg")

yolo predict model=yolo26n.pt source=image.jpg

Using Custom Inference Code

Yes, the output format is different. If you wrote custom post-processing logic for YOLOv8 or YOLO11 (for example, when running inference with ONNX Runtime or TensorRT), you'll need to update it to handle the new output shape:

For segmentation, pose, and OBB tasks, YOLO26 appends task-specific data to each detection — see the output shapes table above.

Where N is the batch size and nc is the number of classes (e.g., 80 for COCO).

With end-to-end models, post-processing becomes much simpler — for example, when using ONNX Runtime:

import onnxruntime as ort

# Load and run the exported end-to-end model
session = ort.InferenceSession("yolo26n.onnx")
output = session.run(None, {session.get_inputs()[0].name: input_tensor})

# End-to-end output: (batch, 300, 6) → [x1, y1, x2, y2, confidence, class_id]
detections = output[0][0]  # first image in batch
detections = detections[detections[:, 4] > conf_threshold]  # confidence filter — that's it!

Switching to the One-to-Many Head

If you need the traditional YOLO output format (for example, to reuse existing NMS-based post-processing code), you can switch to the one-to-many head at any time by setting end2end=False:

from ultralytics import YOLO

model = YOLO("yolo26n.pt")

# Prediction with NMS (traditional behavior)
results = model.predict("image.jpg", end2end=False)

# Validation with NMS
metrics = model.val(data="coco.yaml", end2end=False)

# Export without end-to-end
model.export(format="onnx", end2end=False)

yolo predict model=yolo26n.pt source=image.jpg end2end=False
yolo val model=yolo26n.pt data=coco.yaml end2end=False
yolo export model=yolo26n.pt format=onnx end2end=False

Export Format Compatibility

Most export formats support end-to-end inference out of the box, including ONNX, TensorRT, CoreML, OpenVINO, TFLite, TF.js, and MNN.

The following formats do not support end-to-end and automatically fall back to the one-to-many head: NCNN, RKNN, PaddlePaddle, ExecuTorch, IMX, and Edge TPU.

Accuracy and Speed Tradeoffs

End-to-end detection provides significant deployment benefits with minimal impact on accuracy:

For most real-world applications, the ~0.5 mAP difference is negligible, especially when considering the speed and simplicity gains. If maximum accuracy is your top priority, you can always fall back to the one-to-many head using end2end=False.

See the YOLO26 performance metrics for detailed benchmarks across all model sizes (n, s, m, l, x).

Migrating from YOLOv8 or YOLO11

If you're upgrading an existing project to YOLO26, here's a quick checklist to ensure a smooth transition:

• Ultralytics API / CLI users: No changes needed — just update the model name to yolo26n.pt (or yolo26n-seg.pt, yolo26n-pose.pt, yolo26n-obb.pt)
• Custom post-processing code: Update to handle the new output shapes — (N, 300, 6) for detection, plus task-specific data for segmentation, pose, and OBB. Also note the box format change from xywh to xyxy
• Export pipelines: Check the format compatibility section above for your target format
• TensorRT + INT8: Verify your TensorRT version is >10.3.0 for end-to-end support
• FP16 exports: If you need all outputs in FP16, export with end2end=False — see why output0 stays FP32
• iOS / CoreML: End-to-end is fully supported. If you need Xcode Preview support, use end2end=False with nms=True
• Edge devices (NCNN, RKNN): These formats auto-fallback to one-to-many, so include NMS in your on-device pipeline

FAQ

Can I use end2end=True and nms=True together?

No. These options are mutually exclusive. If you set nms=True on an end-to-end model during export, it will be automatically forced to nms=False with a warning. The end-to-end head already handles duplicate filtering internally, so external NMS is unnecessary.

However, end2end=False combined with nms=True is a valid configuration — it bakes traditional NMS into the export graph. This can be useful for CoreML exports because it lets you use the Preview function in Xcode with the detection model directly.

What does the max_det parameter control in end-to-end models?

The max_det parameter (default: 300) sets the maximum number of detections the one-to-one head can output per image. You can adjust it at inference or export time:

model.predict("image.jpg", max_det=100)  # fewer detections, slightly faster
model.export(format="onnx", max_det=500)  # more detections for dense scenes

Note that the default YOLO26 checkpoints were trained with max_det=300. While you can increase this value, the one-to-one head was optimized during training to produce up to 300 clean detections, so detections beyond that limit may be lower quality. If you need more than 300 detections per image, consider retraining with a higher max_det value.

My exported ONNX model outputs (1, 300, 6) — is that correct?

Yes, that's the expected end-to-end output format for detection: batch size of 1, up to 300 detections, each with 6 values [x1, y1, x2, y2, confidence, class_id]. Simply filter by confidence threshold and you're done — no NMS needed.

For other tasks, the output shape differs:

How do I check if my exported model is end-to-end?

You can check using either the Ultralytics Python API or by inspecting the exported ONNX model metadata directly:

from ultralytics import YOLO

model = YOLO("yolo26n.onnx")
model.predict(verbose=False)  # run predict to setup predictor first
print(model.predictor.model.end2end)  # True if end-to-end is enabled

import onnxruntime as ort

session = ort.InferenceSession("yolo26n.onnx")
metadata = session.get_modelmeta().custom_metadata_map
print(metadata.get("end2end"))  # 'True' if end-to-end is enabled

Alternatively, check the output shape — end-to-end detection models output (1, 300, 6), while traditional models output (1, nc + 4, 8400). For other task shapes, see the output shapes FAQ.

Is end-to-end supported for segmentation, pose, and OBB tasks?

Yes. All YOLO26 task variants — detection, segmentation, pose estimation, and oriented object detection (OBB) — support end-to-end inference by default. The end2end=False fallback is available across all tasks as well.

Each task extends the base detection output with task-specific data:

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