GLM vs GPT-4o: API Cost Compared (2026)

GLM-4.6 runs roughly 6x cheaper than GPT-4o on both sides of the meter, about $0.43 versus $2.50 per million input tokens and $1.74 versus $10 output (GLM measured via OpenRouter), so the real decision is cost versus ecosystem, not raw quality. That gap is large enough to change which projects are even worth shipping, but it comes with a tradeoff most price tables hide, and that is what this piece works through.

GLM vs GPT-4o headline cost (verified 2026-06)

Start with the numbers everyone quotes, then we will say what they actually mean. GPT-4o sits at $2.50 per million input tokens and $10.00 output, and that pricing has been the OpenAI flagship reference point for general chat workloads. GLM-4.6, reached through OpenRouter rather than a native Zhipu key, bills at $0.43 input and $1.74 output. Divide it out and GLM is about 5.8x cheaper on input and 5.7x cheaper on output, which is why the round "roughly 6x" holds on both sides.

According to OpenAI API Pricing, GPT-4o is listed at $2.50 input and $10.00 output per million tokens, and that is the figure the comparison column above is built against. The two GLM rows matter because they are not interchangeable. The $0.43/$1.74 line is what we were actually billed routing through OpenRouter; the $0.60/$2.20 line is Zhipu's own published rate, which we have not yet re-verified against a native key.

What "via OpenRouter" changes about the GLM price

A price you can route to is not always the price the vendor advertises. According to Z.ai Pricing, GLM-4.6 on Zhipu's international platform is listed at $0.60 input and $2.20 output per million tokens, which is higher than the $0.43/$1.74 we measured through OpenRouter. So the cheapest GLM-4.6 path we can confirm today is the third-party route, not the first-party one. We flag this rather than smooth it over, because the official figure still needs native-key re-verification before we would budget a production system against it.

GLM-4.6 is a Zhipu (Z.ai) general-purpose large language model that targets the same chat-and-reasoning slot as GPT-4o while pricing an order of magnitude lower. The naming maps to capability tiers, not to a single SKU, so the rate you pay depends on which tier and which route you pick, and the spread between those routes is wider than the spread inside GPT-4o's own lineup.

We called GLM-4.6 ourselves (first-hand evidence)

Documentation gives you a rate card. A real call tells you what a request actually costs, so we ran one. Calling z-ai/glm-4.6 through OpenRouter with a short general-purpose prompt, the request consumed 32 input tokens and 200 output tokens, billed at $0.00036376, and returned in 8.58 seconds. The output hit our 200-token cap, so treat the completion length as capped rather than the model's natural stopping point.

That is the part a docs-scraping competitor cannot reproduce. The practical upshot: a 232-token round trip on GLM-4.6 costs about a third of a thousandth of a dollar. The equivalent token mix on GPT-4o, at $2.50/$10, would run roughly $0.00208, so the same trivial call is close to 6x more on the OpenAI side, exactly tracking the headline ratio. At a few thousand calls a day the absolute difference is still cents; at a few million it is the line item your finance team asks about.

When the 6x actually matters, and when it does not

Cost only decides the choice once volume is high enough to feel it. Below maybe a hundred thousand calls a month, a 6x input gap is real but small in dollars, and GPT-4o's ecosystem advantages dominate: mature tool-calling, structured outputs, vision, and a tooling ecosystem that assumes OpenAI-shaped APIs by default. Above that, GLM's pricing starts paying for an extra engineer.

The honest counterweight is that GLM-4.6 is not GPT-4o on every axis. English-first reasoning depth, function-calling reliability, and the breadth of community examples still favor the incumbent. According to Z.ai Pricing, Zhipu also offers a free tier on its Flash models (GLM-4.7-Flash and GLM-4.5-Flash) on the international platform, which is a genuinely zero-cost entry point for prototyping that OpenAI does not match at the GPT-4o tier. That free tier is an official Z.ai offering, not an OpenRouter rate; OpenRouter actually charges for the same Flash model.

If you want a price floor below GLM entirely, look at DeepSeek. According to DeepSeek API Docs, DeepSeek V4-Flash bills at $0.14 input and $0.28 output per million tokens on its official endpoint, cheaper still than GLM and reached through a native key rather than a third-party router. We cover that route in the DeepSeek API pricing hub. The asymmetry is worth naming out loud: our GLM number is OpenRouter-routed while the DeepSeek figure is first-party, so they are not apples-to-apples on billing path even though both undercut GPT-4o heavily.

The verdict is a clean split. Choose GLM-4.6 when your workload is high-volume, cost-sensitive, and your prompts do not lean on GPT-4o-specific tooling. Stay on GPT-4o when ecosystem maturity, vision, or function-calling reliability outweighs a bill that is roughly 6x larger. For the full GLM tier card and the cheaper Flash and Air options, see the GLM API pricing hub.

FAQ

Is GLM cheaper than GPT-4o? Yes, substantially. GLM-4.6 measured via OpenRouter runs $0.43 input and $1.74 output per million tokens against GPT-4o's $2.50 and $10.00, which is roughly 5.8x cheaper on input and 5.7x cheaper on output.

How much did a real GLM-4.6 call cost? On our first-hand test through OpenRouter, a 32-input, 200-output-token call to z-ai/glm-4.6 billed $0.00036376 and returned in 8.58 seconds. The output hit a 200-token cap, so treat that length as capped, not natural.

Is the GLM price the same on Z.ai as on OpenRouter? No. We were billed $0.43/$1.74 routing through OpenRouter, while Z.ai's official list price for GLM-4.6 is $0.60/$2.20. The OpenRouter route was cheaper in our measurement; the official figure still needs native-key re-verification.

Does GLM have a free tier like GPT-4o does not? Yes. Zhipu offers a free tier on its Flash models (GLM-4.7-Flash and GLM-4.5-Flash) on the international platform, a zero-cost prototyping path with no GPT-4o equivalent at that tier.

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This is part of the GLM API pricing hub, where the full tier card and cheaper Flash and Air routes are compared side by side.

Author: Kevin Fan, Customer Success Manager at China LLM Directory, specializing in Chinese LLM ecosystem pricing. Last verified: 2026-06-26.

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