ZMIME
Comparison · 2 models · Updated Oct 4, 2026

Kimi K2.5 vs GPT-5.4 nano

Too close to call on our weighted score (GPT-5.4 nano 68, Kimi K2.5 65). The right pick depends on what you value most.

  1. Moonshot AI

    Kimi K2.5

    Released Jan 27, 2026

    65/100
    • ECI148.0
    • Price$0.60 / $3.00
    • Context262K
    Full specs Remove Kimi K2.5

  2. OpenAI

    GPT-5.4 nano

    Released Mar 17, 2026

    68/100
    • ECI145.8
    • Price$0.20 / $1.25
    • Context400K
    Full specs Remove GPT-5.4 nano

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Too close to call

It is close. Our weighted score puts them within 3 points (GPT-5.4 nano 68/100, Kimi K2.5 65/100), so choose by what matters most for your work: Kimi K2.5 for raw capability, GPT-5.4 nano on price and GPT-5.4 nano for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityKimi K2.5Capabilities Index (ECI): Kimi K2.5 148.0 · GPT-5.4 nano 145.8
  • Lowest priceGPT-5.4 nanoGPT-5.4 nano $0.463 · Kimi K2.5 $1.20 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.4 nanoGPT-5.4 nano 400,000 · Kimi K2.5 262,144 tokens
  • Widest inputsKimi K2.5Kimi K2.5: Text, Images, Video · GPT-5.4 nano: Text, Images
  • Self-hostingKimi K2.5Publishes downloadable weights
How the score is built
MeasureWeightKimi K2.5GPT-5.4 nano
CapabilityCapabilities Index (ECI)50%7673
Price25%4666
Inputs & features15%8070
Context window10%3744
Overall100%65/10068/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

Kimi K2.5 vs GPT-5.4 nano specifications side by side
SpecificationKimi K2.5Moonshot AIGPT-5.4 nanoOpenAI
Capability
Capabilities Index (ECI)148.0 (best)145.8
ECI rank#58 of 148 (best)#75 of 148
GPQA DiamondGraduate-level science questions87.6% (best)78.5%
FrontierMath Tiers 1–3Research-level mathematics—44.9%
OTIS Mock AIME 2024–2025Competition mathematics92.2% (best)87.8%
SWE-bench VerifiedFixing real GitHub issues73.8%—
SimpleQA VerifiedShort factual questions34.3% (best)11.7%
Price per million tokens
Input$0.60$0.20 (best)
Output$3.00$1.25 (best)
Cached input—$0.02
Blended (3:1)$1.20$0.463 (best)
Long-context rateSame rateSame rate
Price sourceMedian of 21 providersOfficial OpenAI API
Limits
Context window262,144 tokens400,000 tokens (best)
Max output262,144 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoNo
AudioNoNo
VideoYesNo
ReasoningYesYeslow · medium · high · xhigh
Tool callingYesYes
Structured outputYesYes
Availability
WeightsOpenProprietary
API model ID—gpt-5.4-nano
API providers2126 (best)
ReleasedJan 27, 2026Mar 17, 2026
Knowledge cutoffJan 2025Aug 31, 2025
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • Kimi K2.5$12.00
  • GPT-5.4 nano$4.50
04 — Questions

Which should you choose?

Which is better: Kimi K2.5 or GPT-5.4 nano?

It is close. Our weighted score puts them within 3 points (GPT-5.4 nano 68/100, Kimi K2.5 65/100), so choose by what matters most for your work: Kimi K2.5 for raw capability, GPT-5.4 nano on price and GPT-5.4 nano for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Kimi K2.5 or GPT-5.4 nano?

GPT-5.4 nano is cheaper at $0.20 input / $1.25 output per million tokens (official OpenAI API price). Kimi K2.5 costs $0.60 input / $3.00 output per million tokens (median across 21 API providers). At a typical mix of three input tokens to one output token, that is $0.463 per million tokens for GPT-5.4 nano versus $1.20 for Kimi K2.5 (2.6× as much).

Which scores higher on benchmarks?

Kimi K2.5 scores higher on the Capabilities Index (ECI): Kimi K2.5 148.0 (#58 of 148) and GPT-5.4 nano 145.8 (#75 of 148). The confidence ranges of the top two overlap (146.5–149.3 vs 143.2–147.7), so treat the gap as small. On individual benchmarks: GPQA Diamond — Kimi K2.5 87.6%, GPT-5.4 nano 78.5%; OTIS Mock AIME 2024–2025 — Kimi K2.5 92.2%, GPT-5.4 nano 87.8%; SimpleQA Verified — Kimi K2.5 34.3%, GPT-5.4 nano 11.7%.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-5.4 nano yet, so there is no like-for-like coding score. On overall capability, Kimi K2.5 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-5.4 nano has the largest context window at 400,000 tokens, against 262,144 for Kimi K2.5. Maximum output per response: Kimi K2.5 up to 262,144, GPT-5.4 nano up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Kimi K2.5 accepts text, images and video; GPT-5.4 nano accepts text and images. Kimi K2.5 handles the widest range of inputs.

Are any of these open source?

Kimi K2.5 publishes its weights and can be self-hosted; GPT-5.4 nano is proprietary.

Which is newer?

GPT-5.4 nano is the newest, released Mar 17, 2026. Kimi K2.5 came out Jan 27, 2026. Knowledge cutoff: Kimi K2.5 Jan 2025, GPT-5.4 nano Aug 31, 2025.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.

05 — Keep comparing

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