Both are OpenAI models. GPT-5.6 Luna is the newer, generally stronger default; reach for GPT-5.4 Mini when its lower price or a specific cost or latency profile matters more than the latest capabilities.
GPT-5.4 Mini and GPT-5.6 Luna are both OpenAI models, so the real question is not which lab to trust but which tier fits your workload and budget. GPT-5.4 Mini is openAI's free, fast workhorse — capable general AI with no subscription needed. GPT-5.6 Luna is the budget, high-throughput GPT-5.6 tier — built for cheap, fast, large-volume work rather than deep long-context reasoning. Since both come from the same lab, the comparison below focuses on the tier-and-cost trade-offs that actually separate them.
Key differences
Price: GPT-5.4 Mini is about 1.3× cheaper on input ($0.75/$4.5 per 1M tokens vs $1/$6 per 1M tokens) — modest, but it adds up at steady volume.
Context window: GPT-5.6 Luna holds 2.5× more — 1M (~1,500 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: GPT-5.6 Luna is the newer model by about 4 months (released July 9, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
GPT-5.4 Mini
GPT-5.6 Luna
Provider
OpenAI (US)
OpenAI (US)
Released
March 17, 2026
July 9, 2026
Context window
400K (~600 pages)
1M (~1,500 pages)
Price (in/out)
$0.75/$4.5 per 1M tokens
$1/$6 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Free for every ChatGPT user: GPT-5.4 Mini — A core design strength of GPT-5.4 Mini.
Fast, low-cost general tasks: GPT-5.4 Mini — A core design strength of GPT-5.4 Mini.
Subagent capabilities: GPT-5.4 Mini — A core design strength of GPT-5.4 Mini.
Cheapest GPT-5.6 tier for high-volume drafting and automation: GPT-5.6 Luna — A core design strength of GPT-5.6 Luna.
Fast, affordable execution while keeping respectable coding: GPT-5.6 Luna — A core design strength of GPT-5.6 Luna.
Same 1M context and programmatic tool calling as its siblings: GPT-5.6 Luna — A core design strength of GPT-5.6 Luna.
Lowest cost at scale: GPT-5.4 Mini — At $0.75/$4.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: GPT-5.6 Luna — Its 1M window is about 2.5× larger, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: GPT-5.4 Mini — At $0.75/$4.5 per 1M tokens it undercuts GPT-5.6 Luna, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: GPT-5.6 Luna — Larger 1M window fits more in one prompt.
Anyone whose priority is free for every chatgpt user: GPT-5.4 Mini — It is specifically built for that.
Anyone whose priority is cheapest gpt-5.6 tier for high-volume drafting and automation: GPT-5.6 Luna — That is its strongest area.
GPT-5.4 Mini: where it fits
OpenAI's free, fast workhorse — capable general AI with no subscription needed. Released March 17, 2026 by OpenAI, it is built for free for every ChatGPT user, fast, low-cost general tasks, subagent capabilities, and native multimodal reasoning.
Its trade-offs are real: smaller context than flagship models, and not for the hardest reasoning. At $0.75 in / $4.5 out per million tokens, it sits in the budget price band.
GPT-5.6 Luna: where it fits
The budget, high-throughput GPT-5.6 tier — built for cheap, fast, large-volume work rather than deep long-context reasoning. Released July 9, 2026 by OpenAI, it is built for cheapest GPT-5.6 tier for high-volume drafting and automation, fast, affordable execution while keeping respectable coding, same 1M context and programmatic tool calling as its siblings, and high-throughput simple agentic jobs.
Its trade-offs: weak long-context recall deep in its 1M window (MRCR far below Sol), and lowest raw capability of the three GPT-5.6 tiers; no open weights. At $1 in / $6 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Because GPT-5.4 Mini and GPT-5.6 Luna come from the same lab (OpenAI), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. GPT-5.6 Luna is the more capable, more recent option; the other earns its place only when its price or latency profile fits a specific job better. Most teams should default to GPT-5.6 Luna and drop down only with a concrete reason.
Frequently asked questions
Is GPT-5.4 Mini or GPT-5.6 Luna better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, GPT-5.4 Mini leans toward free for every chatgpt user while GPT-5.6 Luna leans toward cheapest gpt-5.6 tier for high-volume drafting and automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.4 Mini or GPT-5.6 Luna?
GPT-5.4 Mini is cheaper — $0.75/$4.5 per 1M tokens vs $1/$6 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
GPT-5.6 Luna — 1M vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Should I upgrade from GPT-5.4 Mini to GPT-5.6 Luna?
Since both are OpenAI models, the newer one (GPT-5.6 Luna) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, GPT-5.4 Mini or GPT-5.6 Luna?
GPT-5.6 Luna — released July 9, 2026, about 4 months after GPT-5.4 Mini.
GPT-5.4 Mini vs GPT-5.6 Luna
OpenAI · US | OpenAI · US · Updated June 2026
Quick verdict
Both are OpenAI models. GPT-5.6 Luna is the newer, generally stronger default; reach for GPT-5.4 Mini when its lower price or a specific cost or latency profile matters more than the latest capabilities.
GPT-5.4 Mini and GPT-5.6 Luna are both OpenAI models, so the real question is not which lab to trust but which tier fits your workload and budget. GPT-5.4 Mini is openAI's free, fast workhorse — capable general AI with no subscription needed. GPT-5.6 Luna is the budget, high-throughput GPT-5.6 tier — built for cheap, fast, large-volume work rather than deep long-context reasoning. Since both come from the same lab, the comparison below focuses on the tier-and-cost trade-offs that actually separate them.
Key differences at a glance
▸Price: GPT-5.4 Mini is about 1.3× cheaper on input ($0.75/$4.5 per 1M tokens vs $1/$6 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: GPT-5.6 Luna holds 2.5× more — 1M (~1,500 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: GPT-5.6 Luna is the newer model by about 4 months (released July 9, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
GPT-5.4 Mini
GPT-5.6 Luna
Provider
OpenAI (US)
OpenAI (US)
Released
March 17, 2026
July 9, 2026
Context window
400K (~600 pages)
1M (~1,500 pages)
Price (in/out)
$0.75/$4.5 per 1M tokens
$1/$6 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, image, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Free for every ChatGPT user
GPT-5.4 Mini
A core design strength of GPT-5.4 Mini.
Fast, low-cost general tasks
GPT-5.4 Mini
A core design strength of GPT-5.4 Mini.
Subagent capabilities
GPT-5.4 Mini
A core design strength of GPT-5.4 Mini.
Cheapest GPT-5.6 tier for high-volume drafting and automation
GPT-5.6 Luna
A core design strength of GPT-5.6 Luna.
Fast, affordable execution while keeping respectable coding
GPT-5.6 Luna
A core design strength of GPT-5.6 Luna.
Same 1M context and programmatic tool calling as its siblings
GPT-5.6 Luna
A core design strength of GPT-5.6 Luna.
Lowest cost at scale
GPT-5.4 Mini
At $0.75/$4.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-5.6 Luna
Its 1M window is about 2.5× larger, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-5.4 Mini
At $0.75/$4.5 per 1M tokens it undercuts GPT-5.6 Luna, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-5.6 Luna
Larger 1M window fits more in one prompt.
Anyone whose priority is free for every chatgpt user
→ GPT-5.4 Mini
It is specifically built for that.
Anyone whose priority is cheapest gpt-5.6 tier for high-volume drafting and automation
→ GPT-5.6 Luna
That is its strongest area.
GPT-5.4 Mini: where it fits
OpenAI's free, fast workhorse — capable general AI with no subscription needed. Released March 17, 2026 by OpenAI, it is built for free for every ChatGPT user, fast, low-cost general tasks, subagent capabilities, and native multimodal reasoning.
Its trade-offs are real: smaller context than flagship models, and not for the hardest reasoning. At $0.75 in / $4.5 out per million tokens, it sits in the budget price band.
GPT-5.6 Luna: where it fits
The budget, high-throughput GPT-5.6 tier — built for cheap, fast, large-volume work rather than deep long-context reasoning. Released July 9, 2026 by OpenAI, it is built for cheapest GPT-5.6 tier for high-volume drafting and automation, fast, affordable execution while keeping respectable coding, same 1M context and programmatic tool calling as its siblings, and high-throughput simple agentic jobs.
Its trade-offs: weak long-context recall deep in its 1M window (MRCR far below Sol), and lowest raw capability of the three GPT-5.6 tiers; no open weights. At $1 in / $6 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Because GPT-5.4 Mini and GPT-5.6 Luna come from the same lab (OpenAI), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. GPT-5.6 Luna is the more capable, more recent option; the other earns its place only when its price or latency profile fits a specific job better. Most teams should default to GPT-5.6 Luna and drop down only with a concrete reason.
Want both GPT-5.4 Mini and GPT-5.6 Luna 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.
Is GPT-5.4 Mini or GPT-5.6 Luna better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, GPT-5.4 Mini leans toward free for every chatgpt user while GPT-5.6 Luna leans toward cheapest gpt-5.6 tier for high-volume drafting and automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.4 Mini or GPT-5.6 Luna?
GPT-5.4 Mini is cheaper — $0.75/$4.5 per 1M tokens vs $1/$6 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
GPT-5.6 Luna — 1M vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Should I upgrade from GPT-5.4 Mini to GPT-5.6 Luna?
Since both are OpenAI models, the newer one (GPT-5.6 Luna) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, GPT-5.4 Mini or GPT-5.6 Luna?
GPT-5.6 Luna — released July 9, 2026, about 4 months after GPT-5.4 Mini.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.