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AI Choice Engine

Model comparison

GLM 5.3 Flash vs GPT-5.6 Terra

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

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

Z.ai

GLM 5.3 Flash

Balanced · Open weights

vs

OpenAI

GPT-5.6 Terra

Balanced

AI model capability comparison
SpecificationGLM 5.3 FlashGPT-5.6 Terra
ProviderZ.aiOpenAI
TierBalancedBalanced
Context window1.05MWinner: 1.05M
Max outputNot verifiedUnverified128K
Input / 1M tokensWinner: $0.15$2
Output / 1M tokensWinner: $0.50$12
WeightsOpenClosed
Parameters320B total / 18B active (MoE)Not verifiedUnverified
Reasoning levelslow, high, maxnone, low, medium, high, xhigh, max
Modalitiestext, image, video, filetext, image
LicenseMITNot verifiedUnverified
API model idglm-5.3-flashgpt-5.6-terra
ReleasedAugust 26, 2026July 9, 2026
Artificial Analysis Intelligence Index · source date GLM 5.3 Flash: 2026-10-0142Not verifiedUnverified
Artificial Analysis Intelligence Index [max] · source date GPT-5.6 Terra: 2026-10-01Not verifiedUnverified42
Terminal-Bench 2.1 · source date GLM 5.3 Flash: 2026-0884.3Not verifiedUnverified
Terminal-Bench 2.1 · source date GPT-5.6 Terra: 2026-07-09Not verifiedUnverified87.4
DeepSWE 1.1 · source date GLM 5.3 Flash: 2026-0863.4Not verifiedUnverified
Humanity's Last Exam · source date GLM 5.3 Flash: 2026-0855.3Not verifiedUnverified
LiveBench · source date GPT-5.6 Terra: 2026-09-05Not verifiedUnverified77.9

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

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.

GPT-5.6 Terra: Launch $2.50/$15, reduced to $2/$12 on July 30. Above 272K input the full request bills $4/$18. Cached input $0.20; cache writes $2.50 at short context. Batch $1/$6 at short context. Regional/FedRAMP processing adds 10% where eligible.

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.

BalancedRecord checked October 1, 2026

GPT-5.6 Terra

OpenAI’s middle GPT-5.6 tier for balancing intelligence and cost, with text/image input and a 1.05M-token context.

Best for

  • Cost-sensitive production
  • Mixed reasoning workloads
  • High-volume agents

Watch out

GPT-6.1 Sol lists the same $2 input price and a lower $10 output price than Terra’s $12. Compare representative tasks rather than infer quality from token prices or one index. Terra remains listed in the API model catalog.

When the cheaper one wins

GLM 5.3 Flash is cheaper on output at $0.50 per million tokens against $12 for GPT-5.6 Terra — about 24×. 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 GPT-5.6 Terra at 69.6% / $4.95/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? GLM 5.3 Flash · GPT-5.6 Terra

Common questions

GLM 5.3 Flash vs GPT-5.6 Terra

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

Is GLM 5.3 Flash or GPT-5.6 Terra cheaper for input?
GLM 5.3 Flash is cheaper at $0.15 per million input tokens, against $2 for GPT-5.6 Terra — roughly 13× the price. Estimate both input and output token volume for your workload. These are base rates; 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. GPT-5.6 Terra: Launch $2.50/$15, reduced to $2/$12 on July 30. Above 272K input the full request bills $4/$18. Cached input $0.20; cache writes $2.50 at short context. Batch $1/$6 at short context. Regional/FedRAMP processing adds 10% where eligible.
Is GLM 5.3 Flash or GPT-5.6 Terra cheaper for output?
GLM 5.3 Flash is cheaper at $0.50 per million output tokens, against $12 for GPT-5.6 Terra — roughly 24× the price. Estimate both input and output token volume for your workload. These are base rates; 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. GPT-5.6 Terra: Launch $2.50/$15, reduced to $2/$12 on July 30. Above 272K input the full request bills $4/$18. Cached input $0.20; cache writes $2.50 at short context. Batch $1/$6 at short context. Regional/FedRAMP processing adds 10% where eligible.
Which has the larger context window, GLM 5.3 Flash or GPT-5.6 Terra?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Do GLM 5.3 Flash and GPT-5.6 Terra support the same reasoning levels?
GLM 5.3 Flash exposes low, high, max, while GPT-5.6 Terra exposes none, low, medium, high, xhigh, max.
Should I use GLM 5.3 Flash or GPT-5.6 Terra?
Both are classified in our balanced tier; this editorial grouping does not imply equal capability. GLM 5.3 Flash is a candidate for cost-efficient long-context; GPT-5.6 Terra is a candidate for cost-sensitive production. Compare accuracy, tool reliability, latency and cost on representative tasks.
Can I self-host GLM 5.3 Flash or GPT-5.6 Terra?
GLM 5.3 Flash publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. GPT-5.6 Terra 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 GPT-5.6 Terra — a 13.3x difference at the headline tier.
  • Context: GPT-5.6 Terra takes 1.05M against 1.05M for GLM 5.3 Flash — 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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