GLM 5.1 vs GPT-4.1 Mini

Z.ai · China  |  OpenAI · US · Updated June 2026

Quick verdict

Pick GLM 5.1 for long-horizon autonomous agentic engineering (up to 8-hour runs) or state-of-the-art open-weight coding (topped swe-bench pro at launch). Pick GPT-4.1 Mini for very cheap high-volume text work at $0.40 in / $1.60 out per million tokens or instruction following above its weight class — 84.1% on ifeval, beating gpt-4o. Choose GLM 5.1 if you need self-hosting or data privacy; GPT-4.1 Mini if you want a managed API.

GLM 5.1 (Z.ai, China) and GPT-4.1 Mini (OpenAI, US) line up two different AI ecosystems against each other — a comparison that is as much about cost philosophy and openness as raw capability. GLM 5.1 is an open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours. GPT-4.1 Mini is a cheap, fast 1M-context workhorse with strong instruction following but weak coding — already retired from ChatGPT. They diverge most on price, context window and open vs. closed weights — each quantified below from the models' real specs.

Key differences at a glance

Side-by-side specs

SpecGLM 5.1GPT-4.1 Mini
ProviderZ.ai (China) OpenAI (US)
ReleasedApril 7, 2026 April 14, 2025
Context window200K (~300 pages) 1M (~1,571 pages)
Price (in/out)$1.4/$4.4 per 1M tokens $0.4/$1.6 per 1M tokens
Open weight?Yes — self-hostable No — API only
Modalitiestext, code text, image, code
SWE-Bench VerifiedNot published 23.6%
MRCR v2 @ 1MNot published Not published

Who wins what

Long-horizon autonomous agentic engineering (up to 8-hour runs)

GLM 5.1

GPT-4.1 Mini is comparatively weak here — weak at agentic coding — its 23.6% on SWE-Bench Verified sits below GPT-4o's 33.2%

State-of-the-art open-weight coding (topped SWE-Bench Pro at launch)

GLM 5.1

Open weights make this possible at all — GPT-4.1 Mini is API-only, so it cannot leave the vendor's servers.

Sustained tool use across thousands of calls

GLM 5.1

An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours — and its weights are open while GPT-4.1 Mini is API-only.

Very cheap high-volume text work at $0.40 in / $1.60 out per million tokens

GPT-4.1 Mini

At $0.4/$1.6 per 1M tokens it undercuts GLM 5.1 ($1.4/$4.4 per 1M tokens), and that gap compounds at volume.

Instruction following above its weight class — 84.1% on IFEval, beating GPT-4o

GPT-4.1 Mini

A cheap, fast 1M-context workhorse with strong instruction following but weak coding — already retired from ChatGPT — and it runs cheaper at $0.4/$1.6 per 1M tokens.

Multi-turn coherence for its tier — 35.8% on MultiChallenge, roughly 1.8x GPT-4o mini

GPT-4.1 Mini

A cheap, fast 1M-context workhorse with strong instruction following but weak coding — already retired from ChatGPT — and it carries the larger 1M context.

Lowest cost at scale

GPT-4.1 Mini

At $0.4/$1.6 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.

Largest single-prompt input

GPT-4.1 Mini

Its 1M window is about 5.2× larger than GLM 5.1's 200K, fitting roughly 1,571 pages in one prompt.

Which should you pick?

A cost-sensitive startup shipping high volume

GPT-4.1 Mini

At $0.4/$1.6 per 1M tokens it undercuts GLM 5.1, and on millions of tokens that margin decides the monthly bill.

Someone analysing very long documents or codebases

GPT-4.1 Mini

Larger 1M window fits more in one prompt.

A team with data-privacy or self-hosting needs

GLM 5.1

Open weights let you run it on your own hardware; GPT-4.1 Mini is API-only.

Anyone whose priority is long-horizon autonomous agentic engineering (up to 8-hour runs)

GLM 5.1

It is specifically built for that.

Anyone whose priority is very cheap high-volume text work at $0.40 in / $1.60 out per million tokens

GPT-4.1 Mini

That is its strongest area.

An enterprise with regional data-residency rules

GPT-4.1 Mini or GLM 5.1

Origin (China vs US) affects where data is processed and which compliance regime applies — check the provider's terms for your region.

GLM 5.1: where it fits

An open-weight (MIT) Chinese coding model built for long-horizon agentic engineering, topping SWE-Bench Pro at launch while running autonomously for up to 8 hours. Released April 7, 2026 by Z.ai, it is built for long-horizon autonomous agentic engineering (up to 8-hour runs), state-of-the-art open-weight coding (topped SWE-Bench Pro at launch), sustained tool use across thousands of calls, and self-hostable under a permissive MIT license.

Its trade-offs are real: text-only, with no image, audio, or video input, and 754B-parameter MoE demands heavy GPU resources to self-host. At $1.4 in / $4.4 out per million tokens, it sits in the mid price band.

GPT-4.1 Mini: where it fits

A cheap, fast 1M-context workhorse with strong instruction following but weak coding — already retired from ChatGPT. Released April 14, 2025 by OpenAI, it is built for very cheap high-volume text work at $0.40 in / $1.60 out per million tokens, instruction following above its weight class — 84.1% on IFEval, beating GPT-4o, multi-turn coherence for its tier — 35.8% on MultiChallenge, roughly 1.8x GPT-4o mini, and a full 1M context at flat pricing, with no long-context premium.

Its trade-offs: weak at agentic coding — its 23.6% on SWE-Bench Verified sits below GPT-4o's 33.2%, retired from ChatGPT in February 2026, and OpenAI's own docs now point users to GPT-5 mini instead, and a June 2024 knowledge cutoff, now roughly two years stale, and no reasoning mode. At $0.4 in / $1.6 out per million tokens, it sits in the budget price band.

The bottom line for this matchup

The defining split here is open vs. closed. GLM 5.1 gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. GPT-4.1 Mini gives you a managed, always-updated API with no infrastructure to run. Teams with GPUs, privacy requirements, or huge volume often favour the open model; teams that want zero ops and the latest capabilities favour the closed one. Capability is close enough that this operational question, not the benchmark, usually decides it.

Want both GLM 5.1 and GPT-4.1 Mini without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.

See pricing

Frequently asked questions

Is GLM 5.1 or GPT-4.1 Mini better for coding?

Public SWE-Bench figures are not available for GLM 5.1, so the honest test is your own repository — run an identical real bug through both. By design, GLM 5.1 leans toward long-horizon autonomous agentic engineering (up to 8-hour runs) while GPT-4.1 Mini leans toward very cheap high-volume text work at $0.40 in / $1.60 out per million tokens, and that positioning usually predicts which feels better on your codebase.

Which is cheaper, GLM 5.1 or GPT-4.1 Mini?

GLM 5.1 is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while GPT-4.1 Mini is API-metered at $0.4/$1.6 per 1M tokens. For most teams without GPUs, the API model is cheaper to start; at very high volume, self-hosting can win.

Which has the bigger context window?

GPT-4.1 Mini — 1M vs 200K, about 5.2× larger. Useful only if the model actually reasons over the full window, which not all do.

Can I use both GLM 5.1 and GPT-4.1 Mini together?

Yes — a multi-model platform like LumiChats gives you GLM 5.1, GPT-4.1 Mini and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.

Which is newer, GLM 5.1 or GPT-4.1 Mini?

GLM 5.1 — released April 7, 2026, about 12 months after GPT-4.1 Mini.

Related comparisons

Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.