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Cheapest GPT-5 API: Complete Cost Breakdown (May 2026)
OpenAI's GPT-5 family now spans six models from $0.08 to $30 per million tokens. If you're looking for the cheapest GPT-5 API, you have more options than ever — but picking the wrong one can cost you 375x more than necessary.
We break down every GPT-5 family model by price, quality, and use case so you can find the cheapest option that actually works for your workload.
Every GPT-5 Family Model, Ranked by Price
| Model | Input ($/1M tokens) | Output ($/1M tokens) | Context | Tier |
|---|---|---|---|---|
| GPT-oss 20B | $0.08 | $0.35 | 128K | Budget |
| GPT-oss 120B | $0.15 | $0.60 | 128K | Budget |
| GPT-4o mini | $0.15 | $0.60 | 128K | Budget |
| GPT-5 mini | $0.25 | $2.00 | 272K | Budget |
| GPT-5 | $1.25 | $10.00 | 272K | Premium |
| GPT-5.3 Codex | $1.75 | $14.00 | 400K | Mid |
| GPT-5.5 | $5.00 | $30.00 | 1M | Premium |
| GPT-5.5 Pro | $30.00 | $180.00 | 1M | Premium |
The cheapest GPT-5 model (GPT-oss 20B at $0.08) costs 375x less than the most expensive (GPT-5.5 Pro at $30). That's the difference between $7/month and $2,625/month for a 10M token workload.
The Four Budget Tiers
Ultra-Budget: GPT-oss 20B ($0.08/$0.35)
OpenAI's open-weight model is the absolute cheapest GPT-5 option. At $0.08 per million input tokens, it costs less than a penny per request. Best for high-volume, simple tasks: classification, extraction, sentiment analysis, chatbot routing.
Budget: GPT-oss 120B / GPT-4o mini ($0.15/$0.60)
Both priced identically, these are workhorses for everyday tasks. GPT-oss 120B runs on open weights (self-host or via providers like Together.ai), while GPT-4o mini is a hosted API with built-in safety. Good for summarization, Q&A, content generation.
Mid-Range: GPT-5 mini ($0.25/$2.00)
The sweet spot for most developers. GPT-5 mini offers near-GPT-5 quality at a fraction of the cost. With 272K context, it handles complex multi-turn conversations and code generation. 67% cheaper than GPT-5.
Premium: GPT-5 ($1.25/$10.00)
Full GPT-5 for when you need maximum reasoning. Reserve this for the 10-20% of requests that genuinely require it — not every API call.
Monthly Cost Scenarios
Small App (1K requests/day, 2K tokens avg)
Scale App (50K requests/day, 2K tokens avg)
At scale, GPT-5 mini offers 80% of GPT-5's quality at 80% lower cost. For most production workloads, that's the right tradeoff.
Competitor Alternatives Even Cheaper Than GPT-oss
If absolute lowest cost is your priority, models outside the GPT-5 family can beat even GPT-oss pricing:
| Model | Input ($/1M) | Output ($/1M) | vs GPT-oss 20B |
|---|---|---|---|
| Gemini 2.0 Flash Lite | $0.075 | $0.30 | 6% cheaper input |
| Llama 3.1 8B | $0.10 | $0.10 | 25% cheaper output |
| DeepSeek V4 Flash | $0.14 | $0.28 | 20% cheaper output |
| Gemini 2.0 Flash | $0.10 | $0.40 | 13% cheaper input |
Gemini 2.0 Flash Lite is the only API cheaper than GPT-oss 20B on input tokens — but GPT-oss models often produce better output quality for the same price.
The Bottom Line
For most use cases, GPT-5 mini ($0.25/$2.00) is the cheapest GPT-5 API worth using. It delivers 80%+ of GPT-5's quality at 80% lower cost. For truly budget-conscious high-volume workloads, GPT-oss 20B ($0.08) is hard to beat — and if you need even cheaper, Gemini Flash Lite edges it out on input cost.
The smart play: use GPT-5 mini as your default and reserve GPT-5 only for complex reasoning tasks. Use the APIpulse calculator to model your exact workload.
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