API cost decision in 10 seconds

🔥gpt-oss-120b vs 🔥GLM 5.1

Pick GLM 5.1 when budget and context both matter.

Pricing data updated: 2026-05-20T21:08:04Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GLM 5.1 when budget and context both matter.

On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $0 vs $0.13 for gpt-oss-120b, saving $0.13 (100% lower).

Cost-first pickGLM 5.1

Context-first pickGLM 5.1

Sample savings$0.13100%

10x traffic gap$1.29

GLM 5.1 is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $1.29. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GLM 5.1 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	gpt-oss-120b	GLM 5.1
Input-heavy / RAG	5M input + 500K output	GLM 5.1	$0.29	$0
Balanced workload	1M input + 1M output	GLM 5.1	$0.22	$0
Output-heavy chatbot	1M input + 5M output	GLM 5.1	$0.94	$0

Cheaper input GLM 5.1 $0.039 vs $0 / 1M

GLM 5.1 is free for input tokens while gpt-oss-120b costs $0.04 per 1M tokens.

Cheaper output GLM 5.1 $0.18 vs $0 / 1M

GLM 5.1 is free for output tokens while gpt-oss-120b costs $0.18 per 1M tokens.

Larger context GLM 5.1 131.07K vs 202.8K

GLM 5.1 has 71.73K more context (1.55x larger).

Sample workload GLM 5.1 $0.13 vs $0

GLM 5.1 is free for the standard workload while the other model is estimated at $0.13.

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

gpt-oss-120b Calculating… Estimated API cost

GLM 5.1 Calculating… Estimated API cost

Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

GLM 5.1 has the lower input price; GLM 5.1 has the lower output price; GLM 5.1 offers the larger context window. For the 1M input plus 500K output sample, GLM 5.1 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.13 for gpt-oss-120b and $0 for GLM 5.1.

Best Fit

Choose gpt-oss-120b when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Choose GLM 5.1 when you care most about lower input-token price, lower output-token price, and larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $0 vs $0.13 for gpt-oss-120b, saving $0.13 (100% lower).
GLM 5.1 is free for the standard workload while the other model is estimated at $0.13.
GLM 5.1 is free for input tokens while gpt-oss-120b costs $0.04 per 1M tokens.
GLM 5.1 is free for output tokens while gpt-oss-120b costs $0.18 per 1M tokens.
GLM 5.1 has 71.73K more context (1.55x larger).

Head-to-Head Specs

Feature	🔥gpt-oss-120b (OpenAI)	🔥GLM 5.1 (Z.ai)
Input Price prompt tokens per 1M	$0.039	$0
Completion Price per 1M tokens	$0.18	$0
Sample Workload Cost 1M input + 500K output	$0.13	$0
Context Window	131.07K	202.8K
Release Date	2025-08-05	2026-04-07
Popularity	#18	#20

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	GLM 5.1	On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $0 vs $0.13 for gpt-oss-120b, saving $0.13 (100% lower).
High-volume input processing	GLM 5.1	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	GLM 5.1	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	GLM 5.1	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

gpt-oss-120b (free) can replace gpt-oss-120b when lower sample workload cost matters most: $0.
gpt-oss-20b (free) can replace gpt-oss-120b when lower sample workload cost matters most: $0.
gpt-oss-20b can replace gpt-oss-120b when lower sample workload cost matters most: $0.1.

Larger context near this budget

Owl Alpha offers 1.05M context with $0 sample workload cost.
DeepSeek V4 Flash (free) offers 1.05M context with $0 sample workload cost.
Lyria 3 Pro Preview offers 1.05M context with $0 sample workload cost.
Lyria 3 Clip Preview offers 1.05M context with $0 sample workload cost.

Popular competitors

DeepSeek V4 Flash · DeepSeek · #1
Hy3 preview · Tencent · #2
Claude Sonnet 4.6 · Anthropic · #3
Claude Opus 4.7 · Anthropic · #4

Cheaper alternatives

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OpenAI catalog

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Z.ai catalog

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gpt-oss-120b

gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases. It activates 5.1B parameters per forward pass and is optimized...

GLM 5.1

GLM-5.1 delivers a major leap in coding capability, with particularly significant gains in handling long-horizon tasks. Unlike previous models built around minute-level interactions, GLM-5.1 can work independently and continuously on...