ZMIME
Comparison · 3 models · Updated Nov 2, 2026

Seed-OSS-36B-Instruct vs GPT OSS 20B vs Claude Haiku 4.5

Claude Haiku 4.5 comes out ahead, 66 to 60 and 52 on our weighted score, though GPT OSS 20B is 17× cheaper per token.

  1. ByteDance Seed

    Seed-OSS-36B-Instruct

    Released Aug 20, 2025

    60/100
    • ECI—
    • Price—
    • Context524K
    Full specs Remove Seed-OSS-36B-Instruct

  2. OpenAI

    GPT OSS 20B

    Released Aug 5, 2025

    52/100
    • ECI137.8
    • Price$0.07 / $0.25
    • Context131K
    Full specs Remove GPT OSS 20B
  3. Our pick

    Anthropic

    Claude Haiku 4.5

    Released Oct 15, 2025

    66/100
    • ECI142.2
    • Price$1.00 / $5.00
    • Context200K
    Full specs Remove Claude Haiku 4.5
01 — Verdict

Claude Haiku 4.5 is our pick

Claude Haiku 4.5 is the better all-round choice, scoring 66/100 against Seed-OSS-36B-Instruct (60) and GPT OSS 20B (52). It leads on inputs & features. Seed-OSS-36B-Instruct wins on context window. The score weighs capability 67%, inputs & features 20%, context window 13%. Capability uses the average of shared benchmarks (GPQA Diamond and OTIS Mock AIME 2024–2025), because Seed-OSS-36B-Instruct has no Capabilities Index score yet.

  • CapabilitySeed-OSS-36B-InstructShared benchmarks: Seed-OSS-36B-Instruct 69.5% · Claude Haiku 4.5 68.9% · GPT OSS 20B 63.0%
  • Lowest priceGPT OSS 20BGPT OSS 20B $0.115 · Claude Haiku 4.5 $2.00 per 1M tokens (3:1 blend) · Seed-OSS-36B-Instruct unpriced
  • Longest contextSeed-OSS-36B-InstructSeed-OSS-36B-Instruct 524,288 · Claude Haiku 4.5 200,000 · GPT OSS 20B 131,072 tokens
  • Widest inputsClaude Haiku 4.5Seed-OSS-36B-Instruct: Text · GPT OSS 20B: Text · Claude Haiku 4.5: Text, Images, PDFs
  • Self-hostingSeed-OSS-36B-Instruct and GPT OSS 20BPublishes downloadable weights (Apache 2.0)
How the score is built
MeasureWeightSeed-OSS-36B-InstructGPT OSS 20BClaude Haiku 4.5
CapabilityShared benchmarks67%706369
Inputs & features20%353580
Context window13%492532
Overall100%60/10052/10066/100

Left out because at least one model lacks the data: price. The remaining weights were rescaled.

02 — Side by side

Every spec in one table

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

Seed-OSS-36B-Instruct vs GPT OSS 20B vs Claude Haiku 4.5 specifications side by side
SpecificationSeed-OSS-36B-InstructByteDance SeedGPT OSS 20BOpenAIClaude Haiku 4.5Anthropic
Capability
Capabilities Index (ECI)—137.8142.2 (best)
ECI rank—#122 of 165#102 of 165 (best)
GPQA DiamondGraduate-level science questions71.5% (best)60.8%71.2%
OTIS Mock AIME 2024–2025Competition mathematics67.5% (best)65.3%66.7%
SimpleQA VerifiedShort factual questions——13.2%
Price per million tokens
Input—$0.07 (best)$1.00
Output—$0.25 (best)$5.00
Cached input——$0.10
Blended (3:1)—$0.115 (best)$2.00
Long-context rate—Same rateSame rate
Price source—Median of 37 providersOfficial Anthropic API
Limits
Context window524,288 tokens (best)131,072 tokens200,000 tokens
Max output524,288 tokens (best)32,768 tokens64,000 tokens
Inputs and features
TextYesYesYes
ImagesNoNoYes
PDFsNoNoYes
AudioNoNoNo
VideoNoNoNo
ReasoningYesYesYes
Tool callingYesYesYes
Structured outputNoNoYes
Availability
WeightsOpenApache 2.0OpenProprietary
API model ID——claude-haiku-4-5
API providers—4148 (best)
ReleasedAug 20, 2025Aug 5, 2025Oct 15, 2025
Knowledge cutoffJul 2024Jun 2024Feb 28, 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.

  • Seed-OSS-36B-Instruct—
  • GPT OSS 20B$1.20
  • Claude Haiku 4.5$20.00
04 — Questions

Which should you choose?

Which is better: Seed-OSS-36B-Instruct, GPT OSS 20B or Claude Haiku 4.5?

Claude Haiku 4.5 is the better all-round choice, scoring 66/100 against Seed-OSS-36B-Instruct (60) and GPT OSS 20B (52). It leads on inputs & features. Seed-OSS-36B-Instruct wins on context window. The score weighs capability 67%, inputs & features 20%, context window 13%. Capability uses the average of shared benchmarks (GPQA Diamond and OTIS Mock AIME 2024–2025), because Seed-OSS-36B-Instruct has no Capabilities Index score yet.

Which is cheaper, Seed-OSS-36B-Instruct, GPT OSS 20B or Claude Haiku 4.5?

GPT OSS 20B is cheaper at $0.07 input / $0.25 output per million tokens (median across 37 API providers). Claude Haiku 4.5 costs $1.00 input / $5.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $0.115 per million tokens for GPT OSS 20B versus $2.00 for Claude Haiku 4.5 (17× as much). Seed-OSS-36B-Instruct has no published per-token price.

Which scores higher on benchmarks?

Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond and OTIS Mock AIME 2024–2025): Seed-OSS-36B-Instruct 69.5%, Claude Haiku 4.5 68.9% and GPT OSS 20B 63.0%. On individual benchmarks: GPQA Diamond — Seed-OSS-36B-Instruct 71.5%, Claude Haiku 4.5 71.2%, GPT OSS 20B 60.8%; OTIS Mock AIME 2024–2025 — Seed-OSS-36B-Instruct 67.5%, Claude Haiku 4.5 66.7%, GPT OSS 20B 65.3%.

Which is better for coding?

There are no published SWE-bench Verified results for Seed-OSS-36B-Instruct, GPT OSS 20B and Claude Haiku 4.5 yet, so there is no like-for-like coding score. On overall capability, Seed-OSS-36B-Instruct leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.

Which has the bigger context window?

Seed-OSS-36B-Instruct has the largest context window at 524,288 tokens, against 200,000 for Claude Haiku 4.5 and 131,072 for GPT OSS 20B. Maximum output per response: Seed-OSS-36B-Instruct up to 524,288, GPT OSS 20B up to 32,768, Claude Haiku 4.5 up to 64,000 tokens.

Which can read images, PDFs, audio or video?

Seed-OSS-36B-Instruct accepts text; GPT OSS 20B accepts text; Claude Haiku 4.5 accepts text, images and PDFs. Claude Haiku 4.5 handles the widest range of inputs.

Are any of these open source?

Seed-OSS-36B-Instruct and GPT OSS 20B publishes its weights (Apache 2.0) and can be self-hosted; Claude Haiku 4.5 is proprietary.

Which is newer?

Claude Haiku 4.5 is the newest, released Oct 15, 2025. Seed-OSS-36B-Instruct came out Aug 20, 2025; GPT OSS 20B came out Aug 5, 2025. Knowledge cutoff: Seed-OSS-36B-Instruct Jul 2024, GPT OSS 20B Jun 2024, Claude Haiku 4.5 Feb 28, 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 Nov 2, 2026.

05 — Keep comparing

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