# Sonnet 5 vs GLM-5.2 vs everyone: how to pick the cheapest LLM API in 2026

> Source: <https://dev.to/romans/sonnet-5-vs-glm-52-vs-everyone-how-to-pick-the-cheapest-llm-api-in-2026-49ja>
> Published: 2026-07-04 05:10:24+00:00

Two frontier-class models just launched weeks apart — Anthropic's Claude Sonnet 5

(closed, $2/$10 per 1M launch pricing) and Z.AI's GLM-5.2 (open-weight, MIT, ~$1.40/

$4.40 across hosts) — and the first question everyone asks is "which is cheaper?"

The honest answer: it depends on your token mix, your tier, and whether cached

input matters. Here's a repeatable way to answer it for *your* case, using live,

verified pricing.

Providers quote prices in incompatible units — per-1K, per-1M, sometimes per-image

or per-character — and split input, output, and cached-input. Before you can

compare anything, convert all of it to dollars per **1 million** input tokens and

per 1 million output tokens. (This is the single biggest source of "wait, that's

cheaper than I thought" errors.)

Comparing a frontier flagship to a budget model on price alone is meaningless.

Bucket first, then compare within a bucket:

A summarizer is input-heavy; a code generator is output-heavy. Output usually

costs 3-5x input, so a model that looks cheap on input can lose on a

generation-heavy workload. Multiply each rate by your real volume — don't eyeball

the sticker price.

For RAG and agent loops you re-send the same context constantly. Cached-input

pricing is often a huge discount — Sonnet 5's cache hits are **90% cheaper** than

fresh input ($0.20 vs $2.00 /1M) — and it can flip the ranking entirely. If your

workload is cache-heavy, rank by cached-input price, not raw input. (There's a

[live ranking of caching-capable APIs](https://modelpricewatch.com/best-for/prompt-caching)

if you want the current order.)

Prices move — Sonnet 5's own launch pricing reverts from $2/$10 to $3/$15 on Sep 1,

`https://modelpricewatch.com/api/v1/models.json`

.Worked example: for a chat product doing ~2M input / 0.5M output tokens a day, run

those numbers through a cost calculator across your shortlist — and if you re-send

a big system prompt each call, add the cached-input rate. The difference between

Sonnet 5 with caching and a naive flagship default can be the majority of your bill.

*Disclosure: I build and maintain Model Price Watch. The method above works with
any pricing source — I just happen to keep one current.*