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OpenAI GPT-OSS 120B vs GLM 5.2

On provider list prices, OpenAI GPT-OSS 120B costs $0.15 per million input tokens against $1.40 for GLM 5.2: 9.3x apart. Output is $0.60 against $4.40 (7.3x). On Allocate both bill at list plus the 7% transaction fee.

OpenAI GPT-OSS 120BG GLM 5.2
LabOpenAIZai Org
AccessOpen weightsOpen weights
Context window128K tokens256K tokens
List price, input$0.15 / M tokens$1.4 / M tokens
List price, output$0.6 / M tokens$4.4 / M tokens
Cached inputn/a$0.26 / M tokens
LicenseCustom licenseNot listed
Fine-tunableYesYes

Specifications and provider list prices from the Allocate catalog, checked 2026-07-08. Billed price is list plus the 7% transaction fee.

What the numbers say

Take 1,000,000 requests a month at 1,200 input and 350 output tokens each. That workload costs $390 a month on OpenAI GPT-OSS 120B and $3,220 on GLM 5.2 at list: a gap of $2,830, or 8.3x.

GLM 5.2 reads 256K tokens per request against 128K for OpenAI GPT-OSS 120B, 2.0x the window. That decides which one can take whole documents without splitting them.

OpenAI GPT-OSS 120B$0.15$0.60
GLM 5.2$1.40$4.40
InputOutput

Choose OpenAI GPT-OSS 120B for

  • The lower list price ($0.15 in / $0.60 out per M tokens)
OpenAI GPT-OSS 120B details

Choose GLM 5.2 for

  • Agents on open weights
  • Code and structured outputs
  • Fine-tuning toward an owned model
GLM 5.2 details

Common questions

Which is cheaper, OpenAI GPT-OSS 120B or GLM 5.2?

OpenAI GPT-OSS 120B, on this workload shape. At list prices it is $0.15/$0.60 per million tokens in and out against $1.40/$4.40 for GLM 5.2. Billed on Allocate: $0.16/$0.64 against $1.50/$4.71, list plus 7%.

Which has the bigger context window?

GLM 5.2: 262,144 tokens (256K) against 131,072 (128K) for OpenAI GPT-OSS 120B.

Can I fine-tune OpenAI GPT-OSS 120B or GLM 5.2?

Both publish open weights (OpenAI GPT-OSS 120B: Custom license; GLM 5.2: Not listed), so both can be fine-tuned. On Allocate the trained weights stay inside your boundary and belong to you.

Related comparisons

OpenAI GPT-OSS 120B vs GLM 4.7 FP8GLM 5.2 vs GLM 4.7 FP8GLM 5.2 vs GLM 5.1 FP4OpenAI GPT-OSS 120B vs OpenAI GPT-OSS 20BGLM 5.2 vs OpenAI GPT-OSS 20BOpenAI GPT-OSS 120B vs GPT-5.5

Run the numbers on your workload

LLM price comparisonAgent cost calculatorOpenAI GPT-OSS 120BGLM 5.2

Or don’t choose. On Allocate a route name is the contract: point yours at one model today, swap to the other tomorrow, and compare them on your live traffic with per-token metering.

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