AI 101 — What are model parameters?

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A parameter is a number inside an AI model that training adjusts, and the "70B" in a model's name means 70 billion of them. They are not facts, not rules and not code. They are the settings the model learned, and once training stops they are the model: copy those numbers into a file and you have shipped the whole thing.

Why the number sits in the name

Model names carry parameter counts because the count answers the question buyers actually ask: will this fit, and what will it cost to run? Llama 3 70B, Qwen 3 235B, an "8B" you can run on a laptop — the number is a size label, the way 1.5 litres is on a car engine.

Mixture-of-experts models have muddied that reading. Qwen3-235B-A22B holds 235 billion parameters in total but activates 22 billion for each token, according to its model card — 128 experts, eight switched on at a time. You need memory for the 235 billion; you pay compute closer to the 22 billion. That split is why two models with the same number on the label can behave completely differently in a bill.

The mental model

GPT-3 had 175 billion parameters, per the paper that introduced it. Nobody wrote them. Training began with random numbers and nudged every one of them, repeatedly, in whichever direction made the model better at predicting the next token in its training text. Do that across trillions of tokens and the numbers settle into a configuration that encodes grammar, style, reasoning habits and a blurry picture of the world.

So the model is a function: text in, a probability for every possible next token out, computed through dozens of layers of matrix multiplication. The parameters are the matrices. Nothing else is stored — there is no table of facts sitting behind the weights, which is exactly why models make things up and why retrieval systems exist.

The analogy: a mixing desk

Picture a recording studio's mixing desk, with a slider for every parameter. During training an infinitely patient engineer nudges each slider a hair at a time, checks whether the mix sounds better on the next example, and keeps going until the whole desk is dialled in across billions of songs.

Then the desk is locked and the sliders are welded in place. Using the model — inference — is pushing a signal through those locked settings: the audio comes out shaped by them, but nothing moves. This is the part people misread. Chatting with a model does not tune it; your conversation is a temporary note passed alongside the locked desk, not a change to it. Fine-tuning is the exception, and it means running the engineer again on your own data.

What the number actually predicts

Memory, mostly. Each parameter is stored at some precision: at 16 bits it takes two bytes, so 70 billion parameters is roughly 140 GB of weights before you add anything for the context being processed. At 4 bits per parameter the same model is about 35 GB — which is the whole reason quantization exists, and why people talk about a 70B model running on one consumer graphics card.

Cost per token, second. Every token generated sends an input through those matrices once, so a bigger model burns more compute per word unless an architecture like mixture of experts lets it skip most of itself.

Ability, only loosely. Parameter count correlates with capability because bigger models can hold more structure, and scaling laws describe how loss falls as models, data and compute grow. But the trend is not a promise. Training data quality, the number of tokens seen, and the post-training that turns a text predictor into an assistant all move the result at least as much. A well-trained 8B model from 2026 beats a carelessly trained 70B model from 2023 on most tasks you would care about.

Three things people get wrong

"More parameters means smarter." It means bigger. Capability depends on what the model was trained on and how, and distillation routinely produces small models that outperform larger ancestors on narrow work.

"Parameters are where the facts live." A single parameter does not mean "Paris is the capital of France". Knowledge is spread across millions of weights in a form that is hard to read and impossible to edit surgically — which is why correcting one wrong fact by retraining is expensive and unreliable.

"The model learns from me." Not from a chat, and not overnight. Weights change during training or fine-tuning, not during a conversation. What feels like memory is either text kept in the context window or a separate store the application writes to, a distinction that matters for privacy and for anyone promising a model that "gets to know you".

Where to learn more

The GPT-3 paper is the clearest look at what a parameter count meant at the start of this era, and modern model cards — Qwen's included — publish total and active counts side by side, which is now the honest way to read a name. For the practical side, the explainers on quantization and mixture of experts cover the two tricks that decide whether a given model fits on the hardware you have.

If a model's parameter count told you the whole story, what would you want the label to say instead? Write to us via our contact page.

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