GLM-5.3-Flash or Kimi K3: which to choose?

Side-by-side comparison

Criterion	GLM-5.3-Flash	Kimi K3
Developer	Zhipu AI (Z.ai)	Moonshot AI
Released	September 18, 2026	July 16, 2026
Capability index	71.9 / 100	80.7 / 100
Input price	$0.30	$3
Output price	$1.05	$15
Cost of a typical task	$0.008	$0.09
Context window	1,000,000 tokens	1,048,576 tokens
Maximum output	131,072 tokens	1,048,576 tokens
Reasoning mode	Yes	Yes
Tool calling	Yes	Yes
Accepted inputs	text, image, video, PDF	text, image, video
Open weights	Yes	Yes
Knowledge cutoff	Not disclosed	Not disclosed

The match-up at a glance

GLM-5.3-Flash and Kimi K3 are two open-weight models that you can install on your own servers, one from Zhipu AI (Z.ai), the other from Moonshot AI. GLM-5.3-Flash was released on September 18, 2026, Kimi K3 on July 16, 2026.

All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.

Performance

On our capability index, GLM-5.3-Flash scores 71.9 out of 100 and Kimi K3 80.7. Kimi K3 leads by 8.8 points.

On the 5 benchmarks reported for both, GLM-5.3-Flash wins 1 time and Kimi K3 4:

GPQA Diamond (PhD-level science questions): GLM-5.3-Flash 90.2%, Kimi K3 93.1%
OTIS Mock AIME (competition mathematics problems): GLM-5.3-Flash 93.9%, Kimi K3 97.2%
FrontierMath (very hard research-level mathematics): GLM-5.3-Flash 55.8%, Kimi K3 72.2%
FrontierCode (advanced programming tasks): GLM-5.3-Flash 31.8%, Kimi K3 44.2%
APEX-Agents (professional tasks carried out by an agent): GLM-5.3-Flash 52.8%, Kimi K3 47.8%

Budget

GLM-5.3-Flash costs $0.30 per million input tokens and $1.05 per million output tokens; Kimi K3 costs $3 and $15.

For a typical agent task (read 20,000 tokens, write 2,000), expect $0.008 with GLM-5.3-Flash versus $0.09 with Kimi K3. GLM-5.3-Flash is 11.2 times cheaper, a gap that adds up quickly over 1,000 tasks: $81.93 difference.

Run the numbers with your own volumes in the agent cost calculator.

Features and limits

Kimi K3 reads more in one go: 1,048,576 tokens of context (roughly 1,573 pages), versus 1,000,000 for GLM-5.3-Flash.

Reasoning mode: GLM-5.3-Flash yes, Kimi K3 yes. Tool calling: GLM-5.3-Flash yes, Kimi K3 yes. Image input: GLM-5.3-Flash yes, Kimi K3 yes.

Both publish their weights: you can host them yourself.

In short

Our reading of the data:

Choose GLM-5.3-Flash for a lower cost and a more recent release.
Choose Kimi K3 for a higher capability index.

This verdict relies on public figures; it does not replace a trial on your own tasks.

Frequently asked questions

GLM-5.3-Flash or Kimi K3: which is better?

On our index (Epoch AI data), GLM-5.3-Flash scores 71.9 and Kimi K3 80.7 out of 100. The best choice also depends on price and on your use case.

Which one is cheaper?

GLM-5.3-Flash. To read 20,000 tokens and write 2,000, expect $0.008 with GLM-5.3-Flash and $0.09 with Kimi K3 (prices as of October 22, 2026).

Which one has the larger context window?

Kimi K3, with 1,048,576 tokens versus 1,000,000.

Can I run GLM-5.3-Flash or Kimi K3 on my own servers?

Yes, both publish their weights. Check each license before commercial use.