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Model comparison

Claude Sonnet 5 vs GLM 5.3 Flash

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

Recorded profile verification October 2, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below

Anthropic

Claude Sonnet 5

Balanced

vs

Z.ai

GLM 5.3 Flash

Balanced · Open weights

AI model capability comparison
SpecificationClaude Sonnet 5GLM 5.3 Flash
ProviderAnthropicZ.ai
TierBalancedBalanced
Context window1MWinner: 1.05M
Max output128KNot verifiedUnverified
Input / 1M tokens$2Winner: $0.15
Output / 1M tokens$10Winner: $0.50
WeightsClosedOpen
ParametersNot verifiedUnverified320B total / 18B active (MoE)
Reasoning levelslow, medium, high, xhigh, maxlow, high, max
Modalitiestext, imagetext, image, video, file
LicenseNot verifiedUnverifiedMIT
API model idclaude-sonnet-5glm-5.3-flash
ReleasedJune 30, 2026August 26, 2026
Terminal-Bench 2.1 · source date Claude Sonnet 5: 2026-06-3080.4Not verifiedUnverified
Terminal-Bench 2.1 · source date GLM 5.3 Flash: 2026-08Not verifiedUnverified84.3
Humanity's Last Exam · source date Claude Sonnet 5: 2026-06-30, GLM 5.3 Flash: 2026-08 (comparability not verified)57.455.3
LiveBench · source date Claude Sonnet 5: 2026-09-0576Not verifiedUnverified
Artificial Analysis Intelligence Index · source date GLM 5.3 Flash: 2026-10-01Not verifiedUnverified42
DeepSWE 1.1 · source date GLM 5.3 Flash: 2026-08Not verifiedUnverified63.4

Dates beside benchmark scores refer to the linked source’s publication or capture date unless that source explicitly states when it measured the result. A shared URL alone does not establish comparable runs; unverified setups are marked. Prices are USD per million tokens at standard rates, excluding batch and caching discounts. 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 Sonnet 5: Standard $2/$10 per MTok with no long-context surcharge. Cache reads $0.20; 5-minute writes $2.50 and 1-hour writes $4. Batch $1/$5. US-only inference adds 10% where supported. Batch supports 300K output with output-300k-2026-03-24; standard stays 128K. Knowledge cutoff Jan 2026; retirement not sooner than June 30, 2027.

GLM 5.3 Flash: Z.ai API $0.15/$0.50 per MTok; cached input $0.03 and limited-time free cache storage. Hosted docs advertise 1M context and 128K output; the checkpoint config sets 1,048,576 context. An exact endpoint-specific numeric output ceiling is not separately verified. FlashX is a distinct $0.37/$1.25 endpoint; third-party prices require their own checks.

BalancedRecord checked October 1, 2026

Claude Sonnet 5

Claude Sonnet 5 is Anthropic's previous Sonnet generation for high-volume agentic work at $2/$10.

Best for

  • Everyday generation
  • High-volume agents
  • Cost-sensitive work

Watch out

Active legacy. Sonnet 5.5 launched September 28 at the same token price, with breaking changes to thinking, forced tool use, computer use, advisor choices and progress blocks. Sonnet 5 rejects non-default temperature/top_p/top_k; test the exact target model before switching.

BalancedOpen weightsRecord checked October 2, 2026

GLM 5.3 Flash

Z.ai's multimodal MIT-licensed 320B/18B MoE checkpoint and hosted Flash endpoint, with always-enabled reasoning and publisher coding/agent evaluations.

Best for

  • Cost-efficient long-context
  • Multimodal input
  • Coding agents

Watch out

The 320B weights require substantial hardware; memory depends on quantization, runtime and context. Effort low/high/max defaults to max. Flash is on Coding Plan with three times GLM-5.3 quota; FlashX is not on the plan. Half-point off-peak/weekend use applies to plan quota, not per-token API prices. Publisher evaluation generation budgets are not hosted API output caps.

When the cheaper one wins

GLM 5.3 Flash is cheaper on output at $0.50 per million tokens against $10 for Claude Sonnet 5 — about 20×. 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. On DeepSWE 1.1, GLM 5.3 Flash is 63.4% Pass@1 at $0.48/task versus Claude Sonnet 5 at 53.8% / $26.4/task. This compares standard short-context token rates, not total cost per accepted task. Include input, cache, context tiers, schedules, retries and review in your pilot.

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Evidence confidence: Medium

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.
  • 3/5 core specs verified on both sides — Not published for at least one side: max output, parameter count.
  • No directly aligned benchmark setup — No benchmark has matching cited sources, source dates, units, effort and recorded run details on both models.
  • Verified within the last 90 days — Older of the two catalog checks was 25 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 Sonnet 5 · GLM 5.3 Flash

Common questions

Claude Sonnet 5 vs GLM 5.3 Flash

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

Is Claude Sonnet 5 or GLM 5.3 Flash cheaper for input?
GLM 5.3 Flash is cheaper at $0.15 per million input tokens, against $2 for Claude Sonnet 5 — roughly 13× the price. Estimate both input and output token volume for your workload. These are base rates; Claude Sonnet 5: Standard $2/$10 per MTok with no long-context surcharge. Cache reads $0.20; 5-minute writes $2.50 and 1-hour writes $4. Batch $1/$5. US-only inference adds 10% where supported. Batch supports 300K output with output-300k-2026-03-24; standard stays 128K. Knowledge cutoff Jan 2026; retirement not sooner than June 30, 2027. GLM 5.3 Flash: Z.ai API $0.15/$0.50 per MTok; cached input $0.03 and limited-time free cache storage. Hosted docs advertise 1M context and 128K output; the checkpoint config sets 1,048,576 context. An exact endpoint-specific numeric output ceiling is not separately verified. FlashX is a distinct $0.37/$1.25 endpoint; third-party prices require their own checks.
Is Claude Sonnet 5 or GLM 5.3 Flash cheaper for output?
GLM 5.3 Flash is cheaper at $0.50 per million output tokens, against $10 for Claude Sonnet 5 — roughly 20× the price. Estimate both input and output token volume for your workload. These are base rates; Claude Sonnet 5: Standard $2/$10 per MTok with no long-context surcharge. Cache reads $0.20; 5-minute writes $2.50 and 1-hour writes $4. Batch $1/$5. US-only inference adds 10% where supported. Batch supports 300K output with output-300k-2026-03-24; standard stays 128K. Knowledge cutoff Jan 2026; retirement not sooner than June 30, 2027. GLM 5.3 Flash: Z.ai API $0.15/$0.50 per MTok; cached input $0.03 and limited-time free cache storage. Hosted docs advertise 1M context and 128K output; the checkpoint config sets 1,048,576 context. An exact endpoint-specific numeric output ceiling is not separately verified. FlashX is a distinct $0.37/$1.25 endpoint; third-party prices require their own checks.
Which has the larger context window, Claude Sonnet 5 or GLM 5.3 Flash?
GLM 5.3 Flash accepts 1.05M tokens against 1M for Claude Sonnet 5. This only matters if you routinely send very long documents or large codebases.
Do Claude Sonnet 5 and GLM 5.3 Flash support the same reasoning levels?
Claude Sonnet 5 exposes low, medium, high, xhigh, max, while GLM 5.3 Flash exposes low, high, max.
Should I use Claude Sonnet 5 or GLM 5.3 Flash?
Both are classified in our balanced tier; this editorial grouping does not imply equal capability. Claude Sonnet 5 is a candidate for everyday generation; GLM 5.3 Flash is a candidate for cost-efficient long-context. Compare accuracy, tool reliability, latency and cost on representative tasks.
Can I self-host Claude Sonnet 5 or GLM 5.3 Flash?
GLM 5.3 Flash publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. Claude Sonnet 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 Flash costs $0.15 per 1M tokens versus $2 for Claude Sonnet 5 — a 13.3x difference at the headline tier.
  • Context: GLM 5.3 Flash takes 1.05M against 1M for Claude Sonnet 5 — only decisive if your prompts approach the smaller window.
  • Deployment: GLM 5.3 Flash publishes weights you can self-host; the other is API-only.
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