# FFT
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**FFT** (Full Fine-Tuning) updates *all* model weights during training. This provides the deepest level of customization but requires more compute resources and longer training time.

## When to use FFT
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+ Large domain shifts where the model needs fundamental knowledge changes
+ You have a large, high-quality dataset (small datasets risk catastrophic forgetting)
+ You want no adapter overhead at inference time
+ Maximum customization depth is required

## Key differences from LoRA
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+ No `lora_rank`, `lora_alpha`, or `merge_weights` parameters
+ Adds `max_response_length` parameter for controlling generated output length
+ Higher compute cost and longer training time
+ Larger output artifacts (full model weights)
+ Not compatible with [continuous customization](customizing-models-continuous.md) 

For the full parameter reference including FFT-specific hyperparameters, see each technique page: [SFT](customizing-models-sft.md), [DPO](customizing-models-dpo.md), [RFT](customizing-models-rft.md).