# OpenAI GPT-OSS 120B vs GLM 5.3 Flash

On provider list prices, GLM 5.3 Flash costs $0.15 per million input tokens against $0.15 for OpenAI GPT-OSS 120B: effectively level. Output is $0.50 against $0.60 (1.2x).

## Specifications

| | OpenAI GPT-OSS 120B | GLM 5.3 Flash |
| --- | --- | --- |
| Lab | OpenAI | Z.ai |
| Access | Open weights | Open weights |
| Context window | 128K tokens | 1M tokens |
| List price, input | $0.15 / M tokens | $0.15 / M tokens |
| List price, output | $0.60 / M tokens | $0.50 / M tokens |
| Cached input | n/a | $0.03 / M tokens |
| License | Custom license | Not listed |
| Fine-tunable | Yes | Yes |

Specifications and provider list prices from the Allocate catalog, checked 2026-07-21.

## What the numbers say

Take 1,000,000 requests a month at 1,200 input and 350 output tokens each. That workload costs $355 a month on GLM 5.3 Flash and $390 on OpenAI GPT-OSS 120B at list: a gap of $35.

GLM 5.3 Flash reads 1M tokens per request against 128K for OpenAI GPT-OSS 120B, 8.0x the window. That decides which one can take whole documents without splitting them.

## Choose OpenAI GPT-OSS 120B for

- Training toward a model you own

## Choose GLM 5.3 Flash for

- The longer context window (1M vs 128K tokens)
- Published cached-input pricing ($0.03 per M tokens)

## Common questions

### Which is cheaper, OpenAI GPT-OSS 120B or GLM 5.3 Flash?

GLM 5.3 Flash, on this workload shape. At list prices it is $0.15/$0.50 per million tokens in and out against $0.15/$0.60 for OpenAI GPT-OSS 120B. Billed on Allocate: $0.16/$0.54 against $0.16/$0.64.

### Which has the bigger context window?

GLM 5.3 Flash: 1,048,576 tokens (1M) against 131,072 (128K) for OpenAI GPT-OSS 120B.

### Can I fine-tune OpenAI GPT-OSS 120B or GLM 5.3 Flash?

Both publish open weights (OpenAI GPT-OSS 120B: Custom license; GLM 5.3 Flash: Not listed), so both can be fine-tuned. On Allocate the trained weights stay inside your boundary and belong to you.

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[HTML page](https://allocate.network/compare/openai-gpt-oss-120b-vs-z-ai-glm-5-3-flash) · [OpenAI GPT-OSS 120B](https://allocate.network/models/openai-gpt-oss-120b.md) · [GLM 5.3 Flash](https://allocate.network/models/z-ai-glm-5-3-flash.md) · [Machine-readable catalog](https://allocate.network/catalog.json)