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Model comparison

Claude Opus 5.5 vs GLM 5.3

Anthropic against Z.ai, compared on context, price, and verified benchmark results.

Catalog record checked September 26, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

Anthropic

Claude Opus 5.5

Frontier

vs

Z.ai

GLM 5.3

Frontier · Open weights

AI model capability comparison
SpecificationClaude Opus 5.5GLM 5.3
ProviderAnthropicZ.ai
TierFrontierFrontier
Context window1M1M
Max output128K128K
Input / 1M tokens$4Winner: $1.40
Output / 1M tokens$20Winner: $4.40
WeightsClosedOpen
ParametersNot disclosedUnverified753B total (MoE; active count unpublished)
Reasoning levelsadaptivelow, high, max
Modalitiestext, imagetext
LicenseNot disclosedUnverifiedglm-5.3 (custom)
API model idclaude-opus-5-5glm-5.3
ReleasedSeptember 22, 2026August 14, 2026
Artificial Analysis Intelligence Index [max] (2026-09-26)Winner: 57.644.8
Humanity's Last Exam [max] (2026-09-26)61.4Not verifiedUnverified
Humanity's Last Exam (2026-08-14)Not verifiedUnverified62.5
Terminal-Bench 4.0 [max] (2026-09-26)59.6Not verifiedUnverified
Terminal-Bench 4.0 [xhigh] (2026-09-22)66.4Not verifiedUnverified
Terminal-Bench 2.1 (2026-08-14)Not verifiedUnverified88.2
DeepSWE 1.1 (2026-08-14)Not verifiedUnverified66.9
SWE-bench Verified (2026-09-01)Not verifiedUnverified95.4

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

Pricing tiers

Claude Opus 5.5: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22.

GLM 5.3: Token API listed at $1.40/$4.40 per MTok from 2026-08-18 (cached input $0.26); Coding Plan access on a points quota. 1M context, 128K max output per official docs; thinking always on. 753B total MoE per the Hugging Face card (active count unpublished).

FrontierRecord checked September 26, 2026

Claude Opus 5.5

Claude Opus 5.5 is Anthropic's default model for agentic coding and knowledge work — Anthropic says it performs near Fable 5.1 on most work at about 40% lower running cost than Opus 5, and it leads the Artificial Analysis Intelligence Index v4.3.2.

Best for

  • Complex agentic coding
  • Enterprise knowledge work
  • Default frontier model

Watch out

Breaking changes from Opus 5: adaptive thinking cannot be disabled (effort runs low to max, default medium) and forced tool use returns an error. Verbose at max effort, so cap output on cost-sensitive routes.

FrontierOpen weightsRecord checked September 26, 2026

GLM 5.3

GLM 5.3 is Zhipu's flagship (~753B MoE), near the top of the leaderboards, and the current GLM Coding Plan default.

Best for

  • Coding Plan subscribers
  • Long-horizon coding
  • Chinese + English

Watch out

Open weights dropped 2026-08-28 under Z.ai's custom glm-5.3 licence (not a standard open-source licence — review before commercial use; secondary coverage says >$10B-revenue providers need a security review). 5.2/5.1 Coding Plan requests route to 5.3.

When the cheaper one wins

GLM 5.3 is cheaper on output at $4.40 per million tokens against $20 for Claude Opus 5.5 — about 4.5×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

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Evidence confidence: High

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • 2 shared named benchmarks with differing scores — Measured on: Artificial Analysis Intelligence Index, Humanity's Last Exam.
  • Verified within the last 90 days — Newest catalog check was 2 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? Claude Opus 5.5 · GLM 5.3

Common questions

Claude Opus 5.5 vs GLM 5.3

Answered from the verified figures on this page rather than general guidance.

Is Claude Opus 5.5 or GLM 5.3 cheaper for input?
GLM 5.3 is cheaper at $1.40 per million input tokens, against $4 for Claude Opus 5.5 — roughly 2.9× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Opus 5.5 has tiered pricing: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22. GLM 5.3 has tiered pricing: Token API listed at $1.40/$4.40 per MTok from 2026-08-18 (cached input $0.26); Coding Plan access on a points quota. 1M context, 128K max output per official docs; thinking always on. 753B total MoE per the Hugging Face card (active count unpublished).
Is Claude Opus 5.5 or GLM 5.3 cheaper for output?
GLM 5.3 is cheaper at $4.40 per million output tokens, against $20 for Claude Opus 5.5 — roughly 4.5× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Opus 5.5 has tiered pricing: $4/$20 per MTok, no long-context surcharge. Cache reads $0.20; 5-minute cache writes $5, 1-hour writes $8. Batch $2/$10; Fast mode $8/$40. Batches API allows 300K output with the output-300k-2026-03-24 beta header. Knowledge cutoff Jun 2026; retirement not before 2027-09-22. GLM 5.3 has tiered pricing: Token API listed at $1.40/$4.40 per MTok from 2026-08-18 (cached input $0.26); Coding Plan access on a points quota. 1M context, 128K max output per official docs; thinking always on. 753B total MoE per the Hugging Face card (active count unpublished).
Which has the larger context window, Claude Opus 5.5 or GLM 5.3?
Both accept about 1M tokens of context, so document length will not decide between them.
Do Claude Opus 5.5 and GLM 5.3 support the same reasoning levels?
Claude Opus 5.5 exposes adaptive, while GLM 5.3 exposes low, high, max.
Should I use Claude Opus 5.5 or GLM 5.3?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. Claude Opus 5.5 suits complex agentic coding; GLM 5.3 suits coding plan subscribers.
Can I self-host Claude Opus 5.5 or GLM 5.3?
GLM 5.3 publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. Claude Opus 5.5 is a closed model whose supported access paths are controlled by its provider.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: GLM 5.3 costs $1.40 per 1M tokens versus $4 for Claude Opus 5.5 — a 2.9x difference at the headline tier.
  • Measured capability: Claude Opus 5.5 leads Artificial Analysis Intelligence Index 57.6 to 44.8 (measured 2026-09-26).
  • Deployment: GLM 5.3 publishes weights you can self-host; the other is API-only.
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