What it takes to train a large language model

Six steps turn raw text into a chatbot. Each one draws on five resources: data, compute, energy, time, and people. Pretraining burns most of the compute and power, but the bill is mostly chips and staff, and the biggest labs now share the least.

DataComputeEnergyTimePeople

The six steps, and what each one uses

The bars under each step show how heavily it draws on each resource: one segment is light use, three is the main cost of that step. The shaded step is where most of the money and power goes.

The steps loop. Problems found in testing or in use send teams back to the data or to fine-tuning, so a model is never really finished after step 6.

Bar levels are my judgment, based on the examples shown and the sources in the footer.

Five resources and how each one drives cost

The assignment names data, compute, energy, and time. I added people because research staff are one of the two largest costs, even though they never appear in a GPU count.

ResourceWhat drives itHow it is measured, with an exampleShare of a frontier model's cost

Eight models, side by side

Every number carries a tag that says where it came from. Gaps are real: the companies behind GPT-4, Gemini, and Claude have not published these figures.

R Reported by the developer E Estimated by researchers C My calculation from reported numbers S Executive's public statement n/d Not disclosed

What the numbers say

121×

more compute for Llama 3.1 405B than for GPT-3, four years apart. Compute is roughly 6 × parameters × training tokens, and both grew.

2–6%

of a frontier model's cost is energy. Chips and servers (47–64%) and staff (29–49%) dominate, yet Llama 3.1 still emitted about 16 times GPT-3's carbon.

0.2%

of DeepSeek-V3's GPU time went to post-training. Alignment is cheap in compute but heavy in human work: labelers, red-teamers, and months of testing.

$40M or $78M?

Two careful estimates of GPT-4's cost differ by about two times because they count different things. Without disclosure, every frontier number is a range.