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OpenAI GPT-5 Model Guide: Every Model Explained (March 2026)

The complete guide to OpenAI's GPT-5 model family in 2026: GPT-5.4, 5.3 Codex, 5.3 Instant, 5.2, Mini, and Nano. Pricing, context windows, benchmarks, and a clear decision framework for choosing the right model.

Published
2026-03-27
Author
ZBuild Team
Reading Time
6 min read
openai gpt-5 modelsgpt 5.4gpt 5.3 codexgpt 5.3 instantwhich gpt model to useopenai model comparison 2026
OpenAI GPT-5 Model Guide: Every Model Explained (March 2026)
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Key Takeaways

  • GPT-5.4 is the new default: Launched March 5, 2026, it merges GPT-5.3 Codex's coding prowess with broader reasoning, a 1M-token context, and native computer use.
  • Six models serve different needs: Flagship (5.4), balanced (5.4 Mini), fast (5.4 Nano), coding specialist (5.3 Codex), everyday (5.3 Instant), and legacy (5.2 Thinking).
  • Price spans 10x: From $0.30/MTok (GPT-5.3 Instant) to $2.50/MTok (GPT-5.4) on input — choosing the right model directly impacts your bill.
  • GPT-5.2 retires June 5: Migrate now to avoid disruption.

The Complete Guide to OpenAI's GPT-5 Model Family

OpenAI's GPT-5 family has grown into six distinct models, each optimized for a different trade-off between capability, speed, and cost. Choosing the wrong model means either overpaying for simple tasks or under-powering complex ones.

This guide covers every model, with pricing, benchmarks, and a clear decision framework.


The Full Lineup (March 2026)

ModelRoleInput CostOutput CostContextReleased
GPT-5.4Flagship reasoning + coding$2.50/MTok$10.00/MTok1.05MMar 5, 2026
GPT-5.4 MiniFast balancedLowerLowerSmallerMar 2026
GPT-5.4 NanoLowest latencyLowestLowestSmallestMar 2026
GPT-5.3 CodexCoding specialist$1.75/MTok$7.00/MTok400KMar 3, 2026
GPT-5.3 InstantEveryday tasks~$0.30/MTok~$1.20/MTokStandardMar 3, 2026
GPT-5.2 ThinkingLegacy flagshipHigherHigherSmallerPrevious

Sources: OpenAI API Models, FelloAI Comparison


GPT-5.4: The New Flagship

GPT-5.4 is OpenAI's most capable model — the first to merge frontier reasoning with frontier coding in a single architecture.

What Makes It Special

  • 1,050,000-token context window — Process entire large codebases, complete documentation sets, and long conversation histories without chunking
  • Native computer use — Interact with desktop applications, browsers, and system tools programmatically
  • 57.7% on SWE-Bench Pro — State-of-the-art coding benchmark performance
  • 83% on GDPval knowledge tasks — Matches or exceeds industry professionals
  • Token efficientFewer output tokens per task despite higher nominal pricing

When to Use GPT-5.4

  • Complex coding tasks requiring deep reasoning
  • Multi-step autonomous workflows (via Codex CLI)
  • Long-context analysis (>400K tokens)
  • Tasks requiring computer use capabilities
  • Any new project where you need the best model available

Pricing

TierInputOutputCached Input
Standard$2.50/MTok$10.00/MTok$0.63/MTok

GPT-5.4 Mini: The Balanced Choice

GPT-5.4 Mini inherits GPT-5.4's architecture at a lower cost and latency point. It's designed for applications that need good reasoning without paying flagship prices.

When to Use GPT-5.4 Mini

  • Production APIs where cost per request matters
  • Applications needing a balance of speed and quality
  • Chatbot backends with moderate complexity
  • Workflows where GPT-5.4 is overkill but GPT-5.3 Instant isn't enough

GPT-5.4 Nano: The Speed Demon

GPT-5.4 Nano is optimized for the lowest possible latency. It trades reasoning depth for raw speed.

When to Use GPT-5.4 Nano

  • Real-time autocomplete and suggestions
  • Latency-critical production endpoints
  • High-volume, low-complexity classification tasks
  • Mobile applications where response time is critical

GPT-5.3 Codex: The Coding Specialist

GPT-5.3 Codex remains the best model for cost-sensitive, input-heavy coding workflows. It runs 25% faster than GPT-5.2 Codex and costs less per input token than GPT-5.4.

When to Use GPT-5.3 Codex

  • Terminal-heavy batch coding operations
  • Workflows that repeatedly send large repository context
  • Cost-optimized agentic coding pipelines
  • Tasks where the 400K context window is sufficient

When to Upgrade to GPT-5.4

  • You need >400K tokens of context
  • You need computer use capabilities
  • You need knowledge work beyond coding
  • The 43% input cost premium is worth the broader capabilities

Pricing

TierInputOutputCached Input
Standard$1.75/MTok$7.00/MTok$0.44/MTok

GPT-5.3 Instant: The Everyday Workhorse

GPT-5.3 Instant is the cheapest GPT-5 model and the best choice for high-volume, everyday tasks.

Key Strengths

  • 26.8% fewer hallucinations than predecessor models
  • Excellent at: Q&A, how-tos, technical writing, translation
  • Lowest cost: ~$0.30/$1.20 per million tokens
  • High throughput: Optimized for speed

When to Use GPT-5.3 Instant

  • Customer support chatbots
  • Content generation at scale
  • Translation and localization
  • Simple Q&A systems
  • Any high-volume application where cost per request matters most

Pricing

TierInputOutput
Standard~$0.30/MTok~$1.20/MTok

GPT-5.2 Thinking: Legacy (Retiring June 2026)

GPT-5.2 was the previous flagship model. It introduced a three-tier architecture (Instant, Thinking, and Pro) but has been superseded by GPT-5.4 across all benchmarks.

Migration Timeline

  • Now → June 5, 2026: GPT-5.2 Thinking available under Legacy Models
  • June 5, 2026: GPT-5.2 Thinking retired. API calls will fail.
  • Action Required: Update model parameter from gpt-5.2-thinking to gpt-5.4
# Before (will stop working June 5, 2026)
model="gpt-5.2-thinking"

# After
model="gpt-5.4"

Decision Framework: Which Model to Use

By Use Case

Use CaseRecommended ModelWhy
Complex coding + reasoningGPT-5.4Best capability, 1M context
Daily coding (cost-sensitive)GPT-5.3 CodexLower input cost, strong coding
General chatbot/Q&AGPT-5.3 InstantCheapest, fast, low hallucination
Production API (balanced)GPT-5.4 MiniGood quality, reasonable cost
Real-time autocompleteGPT-5.4 NanoLowest latency
Science/researchGPT-5.4Deepest reasoning

By Budget

Monthly BudgetStrategy
<$50GPT-5.3 Instant for everything
$50-200GPT-5.3 Instant + GPT-5.3 Codex for coding
$200-1,000GPT-5.4 as default, GPT-5.3 Instant for simple tasks
$1,000+GPT-5.4 for everything, or hybrid routing

The Router Pattern

The most cost-effective approach for production applications:

Request → Classify Complexity
  ├── Simple (60%) → GPT-5.3 Instant ($0.30/MTok)
  ├── Medium (25%) → GPT-5.4 Mini
  ├── Complex (10%) → GPT-5.4 ($2.50/MTok)
  └── Coding (5%)  → GPT-5.3 Codex ($1.75/MTok)

This pattern can reduce costs by 70-80% compared to running GPT-5.4 for all requests, with minimal quality impact.


GPT-5 vs the Competition

How does the GPT-5 family stack up against Claude and Gemini?

ModelInput CostSWE-BenchContextStrength
GPT-5.4$2.50/MTok57.7% (Pro)1.05MBroadest capability
Claude Opus 4.6$15/MTok80.8% (Verified)1MDeepest reasoning
Claude Sonnet 4.6$3/MTok79.6% (Verified)1MBest value reasoning
Gemini 3.1 ProVariesCompetitive2MLargest context

Each model family has strengths. GPT-5.4 offers the most balanced capability set; Claude leads on coding benchmarks; Gemini leads on context window size.


Beyond the API: Building Without Code

All GPT-5 models are tools for developers. Whether you use GPT-5.4 directly or through Codex CLI, you still need programming knowledge to build applications.

If you want to build an app without writing code, platforms like ZBuild let you describe your application in plain language and get a complete working product — powered by AI models like these behind the scenes.

Try ZBuild free →


Summary

OpenAI's GPT-5 family offers a model for every use case and budget:

ModelOne-Liner
GPT-5.4Best overall, use this if unsure
GPT-5.4 MiniGood balance of speed and cost
GPT-5.4 NanoFastest, for latency-critical apps
GPT-5.3 CodexCheapest per-token for heavy coding
GPT-5.3 InstantCheapest overall, for everyday tasks
GPT-5.2Retiring June 5 — migrate now

The right choice depends on your workload, budget, and latency requirements. When in doubt, start with GPT-5.4 and optimize down to cheaper models as you understand your traffic patterns.


Published by the ZBuild Team. Build apps without coding at zbuild.io.

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FAQ

Common questions

Which GPT-5 model should I use?+
Use GPT-5.4 as your default for complex reasoning and coding. Use GPT-5.3 Instant for fast everyday tasks at lower cost. Use GPT-5.3 Codex for cost-sensitive coding with heavy input. GPT-5.4 Mini and Nano are best for latency-sensitive production applications.
How many GPT-5 models are there?+
OpenAI currently offers 6 GPT-5 family models: GPT-5.4 (flagship), GPT-5.4 Mini (balanced), GPT-5.4 Nano (fastest), GPT-5.3 Codex (coding specialist), GPT-5.3 Instant (everyday tasks), and GPT-5.2 Thinking (legacy, retiring June 2026).
What is GPT-5.4's context window?+
GPT-5.4 has a 1,050,000-token context window via API — the largest in the GPT-5 family. GPT-5.3 Codex has 400,000 tokens. This allows GPT-5.4 to process entire large codebases in a single context.
How much does GPT-5.4 cost?+
GPT-5.4 costs $2.50 per million input tokens and $10.00 per million output tokens. Cached input costs $0.63 per million tokens. It's more expensive than GPT-5.3 models but more token-efficient per task.
Is GPT-5.2 being retired?+
Yes. GPT-5.2 Thinking will be retired on June 5, 2026. OpenAI recommends migrating to GPT-5.4, which exceeds GPT-5.2's capabilities across all benchmarks.
What is GPT-5.3 Instant good for?+
GPT-5.3 Instant is optimized for high-throughput everyday tasks at approximately $0.30/$1.20 per million tokens — the cheapest GPT-5 model. It excels at Q&A, how-tos, technical writing, and translation with 26.8% fewer hallucinations than its predecessors.
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