When to Stop Training
Training doesnβt need to run βforeverβ. In real projects, the best results come from stopping at the right moment:
not too early (model hasnβt learned yet)
not too late (model starts to overfit / memorize)
If this is your first training, start with the Starter Checklist.
Monitor Training Progress
During training, monitor the progress of the model and watch the relationship between:
Loss
mAP
IOU
Iterations
Loss and mAP are shown on a chart like below:

All metrics can wildly vary by:
Data variety
Data size
Annotation accuracy
Model size
Numbers below are only provided for setting an initial ground for newcomers.
Quick Rule (what usually works)
If you only remember one rule:
Stop when validation mAP stops improving for a long time, or when it starts going down while loss keeps going down.
That second case is the classic sign of overfitting.
Common Training Patterns (cheat sheet)
These patterns are common in real use. For each one, look at the chart first, then read the explanation.
Insufficient data

Explanation:
What it means: you donβt have enough signal yet to trust the trend.
Likely causes: too few images, too short run, weak/too small validation split.
What to do: train longer; add data; ensure validation exists and includes real variety.
Low variance

Explanation:
What it means: the model learns the βeasy repetitionβ quickly, then stops getting new information.
Likely causes: repetitive dataset (same background/angle/light), missing negatives, missing edge cases.
What to do: add variety (angles, backgrounds, lighting), add negatives, capture hard cases on purpose.
Overtraining

Overtraining is not always catastrophic, but it usually indicates memorization rather than generalization. For strict environments (fixed camera, fixed lighting), it is acceptable.
What it means: the model is getting better at the training set, but worse at validation (memorization).
Likely causes: not enough variety, too-small validation, duplicates/near-duplicates.
What to do: stop and keep best weights; add more variety; increase validation split; remove duplicates.
Model not learning

Explanation:
What it means: training is not progressing in a meaningful way.
Likely causes: wrong labels/classes, class IDs mismatch, broken annotation format, incorrect config/settings.
What to do: verify
.namesorder vs label IDs; spot-check labels; confirm YOLO format; adjust training settings.
Corrupted dataset

Explanation:
What it means: training is being disrupted by inconsistent or broken data.
Likely causes: corrupted image files, invalid labels, mixed sources/resolutions, βempty-but-contains-objectsβ images.
What to do: run dataset checks; remove corrupted data; fix label format; re-export a clean set.
Good training

Explanation:
What it means: healthy learning and generalization.
Likely causes: consistent labels + enough variety.
What to do: stop when mAP plateaus; validate on real footage / a βgolden setβ; deploy best weights.
Loss
Loss is a training-fit signal. It represents how well the model is fitting the training batches.
Loss is useful, but it can be misleading:
Loss can keep decreasing even when the model is already overfitting.
Loss does not guarantee βreal-world performanceβ.
**2.0 β₯** Loss
Often indicates βlearning has startedβ, but quality may still be poor. Use it as a sign that the pipeline works, not as a finish line.
As shown in the graph above, loss values around 2.0 may not produce accurate models.
**1.0 β₯** Loss
Commonly a usable baseline on many focused datasets.
**0.5 β₯** Loss
Often indicates a well-fit model on a clean, consistent dataset. After this point improvements can be slow, and overfitting risk increases.
mAP
The mAP (mean average precision) metric combines both precision and recall to provide a comprehensive evaluation of the model's accuracy in detecting objects in an image.
It is calculated by evaluating predictions against ground-truth labels at specific IoU thresholds (exact details depend on the training backend/settings).
mAP is only as good as your validation set. If validation images are too few, too βcleanβ, too similar to training, or mislabeled, mAP can look great while the model fails in production.
Practical interpretation:
A stable plateau is often more important than chasing the last +1%.
Very high mAP (like 95β99%) on a small or repetitive dataset is a common overfitting trap.
If mAP peaks then drops, see Over-Fitting.
IOU
IOU (Intersection over Union) measures the overlap between predicted and true bounding boxes for individual object detections. mAP evaluates the overall performance of the object detection model across all object categories, considering both precision and recall.
You can track each IOU in Training Window loggings:

Fine Tuning
Training Time
Define a maximum training time budget based on available computational resources and project constraints. If the model does not achieve satisfactory performance within the allocated time, consider stopping training and exploring other approaches such as:
Manually analyze annotation accuracy
Check class variety
Choose different model sizes and batch sizes
Increase database size
Over-Fitting
Avoid overfitting by monitoring how mAP behaves over time.
The most reliable βreal lifeβ overfit signal is:
loss decreases, but mAP peaks and then gets worse.
Overfitting is not always βcatastrophicβ on very constrained, fixed-camera setups. But if you care about robustness (different lighting, different shifts, different backgrounds), overfitting will show up quickly.
What usually helps:
Add more variety (new days, new lighting, new backgrounds)
Add negatives that look like your real environment
Tighten label consistency (same style across labelers)
Increase validation split so mAP is harder to βcheatβ


Balancing Time and Performance
Balance the training time with the desired model performance. In some cases, additional training iterations may improve performance, but the returns may diminish over time. Weigh the benefits against the computational cost and the urgency of the project.
Usually, depending on class numbers and database size, training process length can vary between a day or a week.
Starter Checklist
Database:
Model:
Training (stop if):
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