AI Model (LLM API) · decision tool

OpenAI GPT-5 vs OpenAI GPT-5 Nano — for your app, not in general

OpenAI GPT-5 or OpenAI GPT-5 Nano? Set your usage, budget and constraints; the verdict, monthly cost and risks update live from verified pricing.

Prices verified 2026-07-13 against official pricing pages · fit weights are our estimates (see methodology) · share the URL to share your configuration

As of Jul 2026, with 50M input tokens/month, 10 millions output tokens / month, a $50 budget for this slot, OpenAI GPT-5 Nano ranks first for these inputs at 81% fit and a StackSays-estimated $6.50/month (OpenAI GPT-5: 43% fit, $162.50/month). Fit weights are our estimates; prices trace to official pages. Change any input below and the verdict recomputes.

Your situation

The verdict updates as you move these.

Input tokens / month (millions)prompts + context + RAG chunks; a modest AI feature runs 10–100MOutput tokens / month (millions)completions; usually 5–20% of input volumeBudget for this slot ($/mo)what you'd accept paying for the AI model layerTeam size1 = solo; bundled platforms save glue time for small teams

Clear pick for your inputs

OpenAI GPT-5 Nanofit 81% · est $6.50/mo

OpenAI's volume tier for classification and extraction

vs OpenAI GPT-5: fit 81% against 43%, est $6.50 against $162.50 per month

OpenAI GPT-5 Nanofit 81%

$6.50/mo

OpenAI GPT-5fit 43%

$162.50/mo

Comparing 2 tools head-to-head. Open the full field (10 options) →

The decision, in plain words

For a solo builder at 50M input tokens/month and a $50.00/mo budget for the AI model slot, OpenAI GPT-5 Nano leads at 81% fit and $6.50/mo. The two rules doing the work: budget fit (~$6.5/mo is 13% of your $50/mo budget); ecosystem maturity (established — our estimate from ecosystem age, docs and hiring pool).

The gap to OpenAI GPT-5 (43% fit) is wide at these inputs — you'd need to change your requirements, not your taste, to flip it.

Honest weak spot of the pick: budget — our estimate from vendor positioning, not a benchmark; budget models degrade first on long agentic chains.

Generated from the calculation above — every number traces to the sourced data; nothing here is written by an AI making things up.

Why OpenAI GPT-5 Nano scores 81%

Budget fit (weight 30, our estimate) — ~$6.5/mo is 13% of your $50/mo budget+30

Exit cost (weight 4, our estimate) — API-only: switching means re-tuning prompts and re-running evals, not rewriting code+0

Ecosystem maturity (weight 8, our estimate) — established — our estimate from ecosystem age, docs and hiring pool+8

Capability tier (weight 14, our estimate) — budget — our estimate from vendor positioning, not a benchmark; budget models degrade first on long agentic chains-3.5

Total (lines sum exactly)34.5

Possible range −56…+56 (sum of active rule weights) · fit % = (total + max) / (2 × max)(34.5 + 56) / 112 = 81%

How the $6.50/mo estimate is calculated

input tokens overage — 50M over 0M included × $0.05/M$2.50

output tokens overage — 10M over 0M included × $0.4/M$4.00

Note — Prompt caching available (cached reads $0.01/M) — not modeled here$0

Monthly total (lines sum exactly)$6.50

What could change this verdict

Cost risk

Estimated now (StackSays estimate, not your final bill)$6.50/mo · API pay-as-you-go

Free-tier statusNo free tier — paid from the first unit

Biggest unpriced/uncertain variablePrompt caching available (cached reads $0.01/M) — not modeled here

Official prices verified 2026-07-13; calculation is deterministic code over those prices.

At a glance

Tool	Free tier	Paid entry	Verified
OpenAI GPT-5	No free tier	Pay-as-you-go — Prompt caching available (cached reads $0.125/M) — not modeled here	2026-07-13
OpenAI GPT-5 Nano	No free tier	Pay-as-you-go — Prompt caching available (cached reads $0.01/M) — not modeled here	2026-07-13

Where did you land?anonymous, one click

Data sources

Tool	Source	Verified
OpenAI GPT-5	OpenRouter live pricing (CalcSays daily sync, fetched 2026-07-13)	2026-07-13
OpenAI GPT-5 Nano	OpenRouter live pricing (CalcSays daily sync, fetched 2026-07-13)	2026-07-13

A monitor re-checks these pages for changes; when a vendor moves a price, the date updates and every verdict recomputes.

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