API cost decision in 10 seconds

NewGPT Luna Latest vs GLM 5.3

Pick GPT Luna Latest for lower cost; pick GLM 5.3 only if the larger context window matters more.

Page updated: 2026-09-14T00:08:12Z Data confirmed: 2026-09-14T02:08:15Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GPT Luna Latest for lower cost; pick GLM 5.3 only if the larger context window matters more.

On the standard 1M input plus 500K output workload, GPT Luna Latest is estimated at $0.8 vs $3.6 for GLM 5.3, saving $2.8 (77.8% lower).

Cost-first pickGPT Luna Latest

Context-first pickGLM 5.3

Sample savings$2.877.8%

10x traffic gap$28

GLM 5.3 has more context, but GPT Luna Latest saves $2.8 on the standard workload. At 10x that traffic, the same price gap is about $28. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GPT Luna Latest stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	GPT Luna Latest	GLM 5.3
Input-heavy / RAG	5M input + 500K output	GPT Luna Latest	$1.6	$9.2
Balanced workload	1M input + 1M output	GPT Luna Latest	$1.4	$5.8
Output-heavy chatbot	1M input + 5M output	GPT Luna Latest	$6.2	$23.4

Cheaper input GPT Luna Latest $0.2 vs $1.4 / 1M

GPT Luna Latest is $1.2 cheaper per 1M input tokens (85.7% lower; 7x difference).

Cheaper output GPT Luna Latest $1.2 vs $4.4 / 1M

GPT Luna Latest is $3.2 cheaper per 1M output tokens (72.7% lower; 3.67x difference).

Larger context GLM 5.3 1.05M vs 1.31M

GLM 5.3 has 260.72K more context (1.25x larger).

Sample workload GPT Luna Latest $0.8 vs $3.6

GPT Luna Latest is $2.8 cheaper on the standard workload (77.8% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

GPT Luna Latest Calculating… Estimated API cost

GLM 5.3 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

GPT Luna Latest has the lower input price; GPT Luna Latest has the lower output price; GLM 5.3 offers the larger context window. For the 1M input plus 500K output sample, GPT Luna Latest is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0.8 for GPT Luna Latest and $3.6 for GLM 5.3.

Best Fit

Choose GPT Luna Latest when you care most about lower input-token price, and lower output-token price.

Choose GLM 5.3 when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, GPT Luna Latest is estimated at $0.8 vs $3.6 for GLM 5.3, saving $2.8 (77.8% lower).
GPT Luna Latest is $2.8 cheaper on the standard workload (77.8% lower).
GPT Luna Latest is $1.2 cheaper per 1M input tokens (85.7% lower; 7x difference).
GPT Luna Latest is $3.2 cheaper per 1M output tokens (72.7% lower; 3.67x difference).
GLM 5.3 has 260.72K more context (1.25x larger).

Head-to-Head Specs

Feature	NewGPT Luna Latest (OpenAI)	GLM 5.3 (Z.ai)
Input Price prompt tokens per 1M	$0.2	$1.4
Completion Price per 1M tokens	$1.2	$4.4
Sample Workload Cost 1M input + 500K output	$0.8	$3.6
Context Window	1.05M	1.31M
Release Date	2026-09-11	2026-08-18

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	GPT Luna Latest	On the standard 1M input plus 500K output workload, GPT Luna Latest is estimated at $0.8 vs $3.6 for GLM 5.3, saving $2.8 (77.8% lower).
High-volume input processing	GPT Luna Latest	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	GPT Luna Latest	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	GLM 5.3	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 Luna Latest when lower sample workload cost matters most: $0.
gpt-oss-20b (free) can replace GPT Luna Latest when lower sample workload cost matters most: $0.
gpt-oss-20b can replace GPT Luna Latest when lower sample workload cost matters most: $0.1.
gpt-oss-120b can replace GPT Luna Latest when lower sample workload cost matters most: $0.12.

Larger context near this budget

Grok 4.20 Multi-Agent offers 2M context with $2.5 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.

Popular competitors

GPT-5.6 Luna · OpenAI · #1
Hy4 preview · Tencent · #2
GLM 5.3 Flash · Z.ai · #3
DeepSeek V4 Flash 0731 · DeepSeek · #4

Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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OpenAI catalog

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Z.ai catalog

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GPT Luna Latest

This model always redirects to the latest model in the GPT Luna family.

GLM 5.3

GLM-5.3 is a large-scale reasoning model from Z.ai, built for complex software engineering and long-horizon agent tasks. It supports text input and output with a 1M-token context window, and improves...