ZMIME
Comparison · 2 models · Updated Oct 4, 2026

Kimi K2.5 vs Grok 4.20 (Reasoning)

Grok 4.20 (Reasoning) comes out ahead, 68 to 65 on our weighted score, though Kimi K2.5 is 23% cheaper per token.

  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. Our pick

    xAI

    Grok 4.20 (Reasoning)

    Released Mar 9, 2026

    68/100
    • ECI152.0
    • Price$1.25 / $2.50
    • Context1M
    Full specs Remove Grok 4.20 (Reasoning)

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Grok 4.20 (Reasoning) is our pick

Grok 4.20 (Reasoning) is the better all-round choice, scoring 68/100 against Kimi K2.5 (65). It leads on capability and context window. Kimi K2.5 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGrok 4.20 (Reasoning)Capabilities Index (ECI): Grok 4.20 (Reasoning) 152.0 · Kimi K2.5 148.0
  • Lowest priceKimi K2.5Kimi K2.5 $1.20 · Grok 4.20 (Reasoning) $1.56 per 1M tokens (3:1 blend)
  • Longest contextGrok 4.20 (Reasoning)Grok 4.20 (Reasoning) 1,000,000 · Kimi K2.5 262,144 tokens
  • Widest inputsSame inputsKimi K2.5: Text, Images, Video · Grok 4.20 (Reasoning): Text, Images, PDFs
  • Self-hostingKimi K2.5Publishes downloadable weights
How the score is built
MeasureWeightKimi K2.5Grok 4.20 (Reasoning)
CapabilityCapabilities Index (ECI)50%7681
Price25%4641
Inputs & features15%8080
Context window10%3760
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 Grok 4.20 (Reasoning) specifications side by side
SpecificationKimi K2.5Moonshot AIGrok 4.20 (Reasoning)xAI
Capability
Capabilities Index (ECI)148.0152.0 (best)
ECI rank#58 of 148#41 of 148 (best)
GPQA DiamondGraduate-level science questions87.6%89.3% (best)
FrontierMath Tiers 1–3Research-level mathematics—44.9%
OTIS Mock AIME 2024–2025Competition mathematics92.2%92.2% (best)
SWE-bench VerifiedFixing real GitHub issues73.8%—
SimpleQA VerifiedShort factual questions34.3% (best)30.2%
Price per million tokens
Input$0.60 (best)$1.25
Output$3.00$2.50 (best)
Cached input—$0.20
Blended (3:1)$1.20 (best)$1.56
Long-context rateSame rateOver 200K: $2.50 / $5.00
Price sourceMedian of 21 providersOfficial xAI API
Limits
Context window262,144 tokens1,000,000 tokens (best)
Max output262,144 tokens (best)30,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoYesNo
ReasoningYesYes
Tool callingYesYes
Structured outputYesYes
Availability
WeightsOpenProprietary
API model ID—grok-4.20-0309-reasoning
API providers21 (best)11
ReleasedJan 27, 2026Mar 9, 2026
Knowledge cutoffJan 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
  • Grok 4.20 (Reasoning)$17.50
04 — Questions

Which should you choose?

Which is better: Kimi K2.5 or Grok 4.20 (Reasoning)?

Grok 4.20 (Reasoning) is the better all-round choice, scoring 68/100 against Kimi K2.5 (65). It leads on capability and context window. Kimi K2.5 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Kimi K2.5 or Grok 4.20 (Reasoning)?

Kimi K2.5 is cheaper at $0.60 input / $3.00 output per million tokens (median across 21 API providers). Grok 4.20 (Reasoning) costs $1.25 input / $2.50 output per million tokens (official xAI API price). At a typical mix of three input tokens to one output token, that is $1.20 per million tokens for Kimi K2.5 versus $1.56 for Grok 4.20 (Reasoning) (1.3× as much).

Which scores higher on benchmarks?

Grok 4.20 (Reasoning) scores higher on the Capabilities Index (ECI): Grok 4.20 (Reasoning) 152.0 (#41 of 148) and Kimi K2.5 148.0 (#58 of 148). The confidence ranges of the top two overlap (149.3–154.4 vs 146.5–149.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.20 (Reasoning) 89.3%, Kimi K2.5 87.6%; OTIS Mock AIME 2024–2025 — Grok 4.20 (Reasoning) 92.2%, Kimi K2.5 92.2%; SimpleQA Verified — Kimi K2.5 34.3%, Grok 4.20 (Reasoning) 30.2%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.20 (Reasoning) yet, so there is no like-for-like coding score. On overall capability, Grok 4.20 (Reasoning) 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?

Grok 4.20 (Reasoning) has the largest context window at 1,000,000 tokens, against 262,144 for Kimi K2.5. Maximum output per response: Kimi K2.5 up to 262,144, Grok 4.20 (Reasoning) up to 30,000 tokens.

Which can read images, PDFs, audio or video?

Kimi K2.5 accepts text, images and video; Grok 4.20 (Reasoning) accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

Kimi K2.5 publishes its weights and can be self-hosted; Grok 4.20 (Reasoning) is proprietary.

Which is newer?

Grok 4.20 (Reasoning) is the newest, released Mar 9, 2026. Kimi K2.5 came out Jan 27, 2026. Knowledge cutoff: Kimi K2.5 Jan 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

Related comparisons