# Int4 QLoRA NF4 Internals: Double Quantization + Paged Optimizer + Bitsandbytes Source Tour

> Source: https://sukruyusufkaya.com/learn/fine-tuning-cookbook/ftc-qlora-nf4-double-quantization-internals
> Updated: 2026-08-23T09:26:44.122Z
> Category: Fine-Tuning Cookbook (Model-by-Model)
> Module: Part X — Quantization Engineering
**TLDR:** NF4 (4-bit NormalFloat) — QLoRA'nın çekirdeği. Normal distributed weights için optimal 4-bit kuantasyon. Double-quantization (scale tensor'unu da quantize et) ile ek %0.4 bit/param tasarrufu. Paged AdamW (CPU RAM'e overflow). bitsandbytes source-code tour.