# Scaling Laws

> The 2020 Kaplan paper said: bigger model, lower loss. The 2022 Hoffmann paper said: you were under-training. Compute goes into two buckets — parameters and tokens — and the split is not obvious.

**Type:** Learn
**Languages:** Python
**Prerequisites:** Phase 7 · 05 (Full Transformer), Phase 7 · 07 (GPT)
**Time:** ~45 minutes

## The Problem

When you have C FLOPs of training compute and want the best model, you face two knobs:

1. **How many parameters (N)?** Bigger model, higher capacity.
2. **How many training tokens (D)?** More data, better use of capacity.

FLOPs scale approximately as `6 × N × D`. You can push N up and D down, or D up and N down. Which is better?

Before 2022, the answer was "push N hard." GPT-3 (2020) was 175B parameters trained on ~300B tokens. A ratio of about 1.7 tokens per parameter. The Kaplan scaling laws backed this up.

Hoffmann et al. (2022), training a small family of models called Chinchilla, found something different: optimal ratio is closer to **20 tokens per parameter**. GPT-3 was 10× undertrained. Chinchilla (70B params, 1.4T tokens) beat GPT-3 (175B, 300B tokens) on every benchmark at 2.5× less inference cost.

2026 is Chinchilla's world — with one important twist. Llama 3 8B was trained on 15 trillion tokens, a ratio of 1,875 tokens per parameter. Ninety-four times past Chinchilla-optimal. Inference cost matters more than training cost for models that will be used at scale, so over-training (past Chinchilla) for a smaller deployable footprint is the 2026 default.

## The Concept

![Chinchilla curves: loss vs compute at various N/D ratios](../assets/scaling-laws.svg)

### The Hoffmann law

From the Chinchilla paper, loss follows:

```
L(N, D) = A / N^α + B / D^β + E
```

- `N` = parameters (non-embedding).
- `D` = training tokens.
- `α ≈ 0.34`, `β ≈ 0.28` (roughly symmetric).
- `E ≈ 1.69`, the irreducible loss ceiling.
- `A ≈ 406`, `B ≈ 411`.

Two terms trade against each other as you scale. Take the derivative w.r.t. `N` at fixed compute (C = 6ND) and solve:

```
N_opt ≈ 0.6 × (C/6)^0.5
D_opt ≈ 0.6 × (C/6)^0.5
D_opt / N_opt ≈ 20
```

Compute-optimal: 20 tokens per parameter.

### Why over-training anyway

Chinchilla-optimal minimizes training loss per training FLOP. But you pay training cost once; inference cost forever.

For a chatbot that serves a trillion tokens per month, inference dominates total cost. Llama's approach: train smaller, longer. 8B at 15T tokens is deeply inference-optimized:

- Fits on consumer GPUs.
- Latency is a fraction of 70B Chinchilla-optimal.
- Quality is close enough for most tasks.

DeepMind's 2024 paper ("Over-training is the new optimal") formalized this. For inference-dominated workloads, the right ratio is closer to 100–500 tokens per parameter depending on serving volume.

### Emergence vs smoothness

Claim: certain abilities (arithmetic, multi-step reasoning, chain-of-thought following) "emerge" suddenly at some scale.

Schaeffer et al. (2023) argued this is a measurement artifact: emergent metrics use discontinuous scoring (exact match, accuracy at threshold) that hide smooth improvement in the underlying logits. Continuous metrics (cross-entropy) show smooth curves.

In 2026 the consensus is: predictions via continuous loss are reliable. Benchmark jumps are often scorer artifacts. Plan budgets against continuous metrics.

### The 2026 picture

Scaling laws still work, but:

| Factor | Changed how |
|--------|-------------|
| Data quality | Curating "good" tokens (Phi-style) shifts curves by >2× effective compute |
| MoE | Total params decouple from active FLOPs; scaling laws per-active-FLOP |
| Post-training | Some capabilities (instruction following, code) shift with SFT+RLHF more than pretraining |
| Multimodality | Image + text tokens scale together; separate curves per modality |
| Synthetic data | Models generate training data; effective compute can compound |

The Muon optimizer (Kimi Moonlight, 2024) showed a ~2× effective-compute gain over AdamW at matched data. Some 2026 training runs use Muon by default. Changes the absolute constant in the scaling law, not its shape.

```figure
scaling-laws
```

## Build It

See `code/main.py`. We implement the Chinchilla loss equation and solve for compute-optimal `(N, D)` at each of several compute budgets.

### Step 1: Chinchilla loss

```python
def chinchilla_loss(N, D, A=406.4, B=410.7, alpha=0.34, beta=0.28, E=1.69):
    return A / N ** alpha + B / D ** beta + E
```

Plot `L` as a contour over `(N, D)` at fixed `C = 6ND`. Find the minimum.

### Step 2: compute-optimal frontier

For compute budgets from `1e17` to `1e25` FLOPs, find `(N, D)` that minimize loss subject to `6ND = C`. Verify the ratio `D/N ≈ 20`.

### Step 3: over-training cost

Compute the extra loss you pay to train a 10× smaller model (1/10 of optimal N, 10× the optimal D). Reports the inference FLOP savings (proportional to N) in exchange.

### Step 4: compare to real models

Drop in known `(N, D)` pairs for GPT-3, Chinchilla, Llama 3 8B, DeepSeek-V3 (active params), and compare predicted vs reported loss.

## Use It

You're unlikely to train a frontier model yourself. But scaling laws tell you:

1. **Whether your fine-tune has enough data.** If your task-specific data is below 20 tokens per param of the base model, expect saturation at some loss floor.
2. **Whether to pick a bigger base model.** If you're spending all your budget on inference, prefer a smaller, longer-trained model.
3. **Where the returns diminish.** Beyond 1000× Chinchilla-optimal, log-loss changes become noise.

**The research trajectory in 2026:**

- **Data-constrained regime.** The web has a finite number of high-quality tokens (~5–10 trillion English after filtering). Frontier pretraining is approaching this ceiling. Synthetic data, multilingual, multimodal, and RLHF-scaled fine-tuning are the next levers.
- **Compute-multiplier tricks.** Muon optimizer, MoE, better data curation — each shifts the absolute constants, not the asymptote.
- **Scaling laws for RL.** Open question. Early evidence suggests power-law in RL samples but with very different exponents than pretraining.

## Ship It

See `outputs/skill-training-budget-estimator.md`. The skill picks `(N, D, hours, GPU)` for a new training run given compute budget, deployment constraints, and target loss.

## Exercises

1. **Easy.** Run `code/main.py`. Print Chinchilla-optimal `(N, D)` for compute budgets `1e20`, `1e22`, `1e24`. Compare to the real model table.
2. **Medium.** Implement the Hoffmann loss-as-function-of-compute curve. Plot loss vs `log10(C)` for the compute-optimal frontier. Identify when the law predicts we'd need `>10^28` FLOPs for the next 0.1 reduction in cross-entropy.
3. **Hard.** Fit your own scaling law on 5 tiny models (100K to 10M params) trained on the same dataset. Estimate `α` and `E`. How well do your exponents match published ones?

## Key Terms

| Term | What people say | What it actually means |
|------|-----------------|-----------------------|
| Parameters (N) | "Model size" | Non-embedding weight count; determines capacity. |
| Tokens (D) | "Training data" | Number of training tokens seen; determines how well the parameters get used. |
| Compute (C) | "FLOPs spent" | Approximately `6 × N × D` for a standard transformer. |
| Chinchilla-optimal | "D/N ≈ 20" | Ratio that minimizes loss per FLOP of pretraining. |
| Over-training | "Past Chinchilla" | Spend extra training FLOPs to save inference FLOPs; D/N >> 20. |
| Irreducible loss | "The floor" | The `E` term in the scaling law; the entropy of the data itself. |
| Emergent capability | "Sudden jumps at scale" | Often a scorer artifact; continuous loss is smooth. |
| Effective compute | "Training-efficiency multiplier" | Better data / optimizer / architecture multiplies how far a FLOP goes. |

## Further Reading

- [Kaplan et al. (2020). Scaling Laws for Neural Language Models](https://arxiv.org/abs/2001.08361) — the first scaling law paper; undertrained.
- [Hoffmann et al. (2022). Training Compute-Optimal Large Language Models](https://arxiv.org/abs/2203.15556) — Chinchilla.
- [Schaeffer et al. (2023). Are Emergent Abilities of Large Language Models a Mirage?](https://arxiv.org/abs/2304.15004) — emergence as measurement artifact.
- [Sardana, Frankle (2024). Beyond Chinchilla-Optimal: Accounting for Inference in Language Model Scaling Laws](https://arxiv.org/abs/2401.00448) — why Llama's over-training is right for its workload.
- [Jordan et al. (2024). Muon: An optimizer for hidden layers in neural networks](https://kellerjordan.github.io/posts/muon/) — 2× compute multiplier.
