Not every application needs GPT-5.5 or Claude Opus 4.7. If you're building a chatbot, a content classifier, a data extraction pipeline, or a high-volume agent, a cheaper model can do the job — and save you 95% or more. The budget AI API market in 2026 is surprisingly capable, and the price differences between models are staggering.
We ranked every major model by input price. Here are the five cheapest, what they can do, and when to use them.
The Rankings
| # | Model | Input | Output | Cache Read | Provider |
|---|---|---|---|---|---|
| 1 | Gemini 2.5 Flash-Lite | $0.10 | $0.40 | $0.01 | |
| 2 | DeepSeek V4 Flash | $0.14 | $0.28 | $0.0028 | DeepSeek |
| 3 | GPT-5.4 Nano | $0.20 | $1.25 | $0.02 | OpenAI |
| 4 | Gemini 2.5 Flash | $0.30 | $2.50 | $0.03 | |
| 5 | DeepSeek V4 Pro* | $0.435 | $0.87 | $0.0036 | DeepSeek |
* DeepSeek V4 Pro: 75% off until May 31, 2026. Original price: $1.74 input, $3.48 output. All prices per million tokens.
GPT-5.5 costs $5.00 input / $30.00 output. That's 50x more expensive than Gemini 2.5 Flash-Lite on input, and 75x more on output. If your task doesn't need frontier intelligence, the savings are enormous.
#1: Gemini 2.5 Flash-Lite — $0.10 / $0.40
The cheapest model from any major provider. At $0.10 per million input tokens, you can process 10 million tokens for a dollar. That's roughly 7.5 million English words — about 10 full-length novels — for less than the price of a gumball.
Flash-Lite is designed for high-throughput, low-complexity tasks. It handles classification, extraction, summarization, and simple Q&A well. It's not going to write elegant code or solve complex reasoning problems, but for the majority of API calls that boil down to "extract this data" or "classify this text," it's the most cost-effective option available.
Best for:
- Data extraction and structured output
- Text classification and sentiment analysis
- Content moderation and filtering
- High-volume batch processing
Cached token pricing:
At $0.01/M for cache reads, cached tokens on Flash-Lite are essentially free. If your application sends the same system prompt repeatedly, the cached portion costs almost nothing.
#2: DeepSeek V4 Flash — $0.14 / $0.28
DeepSeek's speed-optimized model delivers the best output-to-input price ratio on this list. Output tokens cost just $0.28/M — half the price of Gemini 2.5 Flash-Lite's output. For applications where the model generates long responses, DeepSeek V4 Flash is actually cheaper overall despite a slightly higher input price.
DeepSeek V4 Flash also has the most aggressive cache pricing in the industry: $0.0028/M for cache reads. That's a 98% discount from the normal input price. For agent applications that send the same context with every request, DeepSeek's caching makes repeated tokens practically free.
Best for:
- Chatbots and conversational agents
- Code generation and explanation
- Content creation and rewriting
- Agent workflows with cached context
How cheap is it really?
If you run 100,000 requests per day with 2,000 input tokens and 500 output tokens each, your daily cost is $2.38. That's $71 per month for a production chatbot serving thousands of users.
#3: GPT-5.4 Nano — $0.20 / $1.25
OpenAI's entry in the budget tier. Nano is a distilled version of GPT-5.4, optimized for speed and cost. It inherits OpenAI's strong instruction-following and structured output capabilities, making it a reliable choice for tasks that need consistent, well-formatted responses.
The input price is competitive, but output tokens at $1.25/M are more expensive than both DeepSeek options. Nano is best suited for tasks with short outputs — classification labels, extracted fields, yes/no decisions — rather than long-form generation.
Best for:
- Structured data extraction (JSON output)
- Intent classification for chatbots
- Short-form content (titles, summaries, tags)
- Function calling and tool use
If you're already using GPT-5.5 or GPT-5.4 for complex tasks, adding Nano as a fallback for simple queries keeps everything in one API. No need to manage multiple providers — just route by complexity.
#4: Gemini 2.5 Flash — $0.30 / $2.50
The step up from Flash-Lite. Gemini 2.5 Flash is Google's workhorse model — fast, capable, and cheap. It handles more complex tasks than Flash-Lite, including multi-step reasoning, code generation, and longer-context analysis. If Flash-Lite feels too limited for your use case, Flash is usually the right upgrade.
At $0.30 input, it's 3x the price of Flash-Lite but still 17x cheaper than GPT-5.5. The output price of $2.50/M is where it gets less competitive — for output-heavy tasks, DeepSeek V4 Flash ($0.28) is nearly 9x cheaper.
Best for:
- General-purpose chatbots
- Code assistance and debugging
- Document analysis and summarization
- RAG (Retrieval-Augmented Generation) pipelines
#5: DeepSeek V4 Pro* — $0.435 / $0.87
DeepSeek's flagship model at a steep promotional discount. The asterisk matters: these prices reflect a 75% discount valid until May 31, 2026. After that, the price jumps to $1.74/$3.48 — still cheap, but no longer in the top 5.
At promotional pricing, V4 Pro is an extraordinary value. It's DeepSeek's most capable model, rivaling Claude Sonnet and GPT-5.4 on many benchmarks. The output price of $0.87/M is the second-cheapest on this entire list — you can generate long, detailed responses without worrying about cost.
Best for:
- Code generation and review (strong coding benchmarks)
- Complex reasoning tasks on a budget
- Long-form content creation
- Any task that needs more than Flash-level capability
The 75% discount ends May 31, 2026. After that, V4 Pro costs $1.74/$3.48 — still affordable, but 4x more expensive than today. If you're building a production system, budget for the post-promotion price.
Head-to-Head: Which Is Actually Cheapest?
The "cheapest" model depends on your input/output ratio. Here's a comparison for a typical workload — 100K requests/day, 2,000 input tokens, 500 output tokens per request:
| Model | Daily Cost | Monthly Cost | vs. GPT-5.5 |
|---|---|---|---|
| Gemini 2.5 Flash-Lite | $1.00 | $30 | 99.6% cheaper |
| DeepSeek V4 Flash | $2.38 | $71 | 99.1% cheaper |
| GPT-5.4 Nano | $2.50 | $75 | 99.0% cheaper |
| Gemini 2.5 Flash | $8.50 | $255 | 96.6% cheaper |
| DeepSeek V4 Pro* | $11.50 | $345 | 95.4% cheaper |
| GPT-5.5 (reference) | $250.00 | $7,500 | — |
Every model on this list costs less than $350/month for a workload that would cost $7,500 on GPT-5.5. That's not a marginal saving — it's a fundamentally different cost structure.
When to Use a Budget Model (and When Not To)
Use a budget model when:
- The task is well-defined and constrained (extract, classify, summarize)
- You need high throughput (10K+ requests/day)
- Output quality has a clear "good enough" threshold
- You're prototyping and want to minimize burn rate
- You're building a pipeline where a cheap model handles 90% of cases and a premium model handles edge cases
Stick with a frontier model when:
- The task requires complex, multi-step reasoning
- Accuracy is critical and errors are costly (legal, medical, financial)
- You need the model to write production-quality code
- The task involves nuanced judgment or creative work
- You're using the model as the core product, not a utility
The smartest architecture uses cheap models for the heavy lifting and expensive models for the hard problems. Route 90% of your traffic to a $0.10/M model and reserve the $5.00/M model for the 10% that actually needs it.
Cache Pricing: The Hidden Multiplier
If your application sends the same system prompt or context with every request, cache read pricing matters more than normal input pricing. Here's how the five cheapest models compare on cached tokens:
| Model | Normal Input | Cache Read | Cache Savings |
|---|---|---|---|
| DeepSeek V4 Flash | $0.14 | $0.0028 | 98% |
| DeepSeek V4 Pro* | $0.435 | $0.0036 | 99% |
| Gemini 2.5 Flash-Lite | $0.10 | $0.01 | 90% |
| GPT-5.4 Nano | $0.20 | $0.02 | 90% |
| Gemini 2.5 Flash | $0.30 | $0.03 | 90% |
DeepSeek's cache pricing is in a league of its own. At $0.0028/M, cached tokens on V4 Flash cost less than 1/50th of a cent. If your agent sends a 5,000-token system prompt 50,000 times per day, the cached portion costs $0.07 per day. Not per thousand — per day.
Calculate your costs with any model
Open Cost CalculatorThe Bottom Line
AI API pricing has collapsed. A task that cost $100 per day two years ago now costs $1. The models on this list aren't toys — they're production-grade systems powering real applications at companies of every size. Gemini 2.5 Flash-Lite at $0.10/M is the cheapest option from a major provider. DeepSeek V4 Flash at $0.14/$0.28 offers the best all-around value. And DeepSeek V4 Pro at its promotional price delivers frontier capability for pocket change.
The key is matching the model to the task. Don't pay $5/M for GPT-5.5 to classify emails. Don't use Flash-Lite to write complex code. Pick the right tool, use caching aggressively, and your AI API bill drops from a line item to a rounding error.
Pricing sourced from official provider documentation (May 2026). DeepSeek V4 Pro pricing reflects the 75% promotional discount valid until May 31, 2026. Cache TTL, minimum lengths, and pricing may change. Always verify current rates on the provider's pricing page.