Cheapest LLM for Customer Support
Find the most cost-effective AI model for your support chatbot. Compare GPT-5, Claude, Gemini, and DeepSeek on a real support workload.
Inputs
Select a use case to pre-fill realistic token and request defaults, or choose Custom.
The model you are using in production today.
Average prompt size per API call — system prompt + context + user message. Typical: simple chat 500–2,000 · RAG chatbot 2,000–8,000 · document analysis 10,000–100,000 tokens.
Average response length. Short answer: 200–500 · paragraph: 500–1,000 · long-form: 1,000–4,000 tokens.
Total API calls per month. 1,000 DAU × 5 calls/day × 30 days = 150,000 requests/month.
Fraction of input tokens currently served from Prompt Cache. 0 = not using cache.
Decision Summary
Saves $2,360.96/yr (98.4%) with high engineering effort. See the ranked table below for all options.
Comparison
| Option | Monthly | Yearly |
|---|---|---|
| Best combo: DeepSeek V4 Flash + cache + batchMaximum possible savings: optimal model, 60% cache, batch API enabled.cheapest | $3.25 | $39.04 |
| Switch to GPT-5 NanoRun a representative quality evaluation against the current model before migrating traffic. | $6.92 | $83.04 |
| Switch to GPT-5 MiniRun a representative quality evaluation against the current model before migrating traffic. | $34.60 | $415.20 |
| Cache (60%) + Batch APIMaximum savings without changing models. | $86.50 | $1,038.00 |
| Switch to Claude Haiku 4.5Run a representative quality evaluation against the current model before migrating traffic. | $93.40 | $1,120.80 |
| Enable Batch API (50% discount)Use async batch endpoint. Suitable for offline / non-realtime workloads. | $100.00 | $1,200.00 |
| Enable Prompt Cache (60% hit)Fix system prompt at context start and reuse across requests. | $173.00 | $2,076.00 |
| Current baselineGPT-5, cache 0%, batch offcurrent | $200.00 | $2,400.00 |
Pricing sources
Last verified 2026-08-03 · developers.openai.com/api/docs/models/compare developers.openai.com/api/docs/models/compare · platform.claude.com/docs/en/about-claude/pricing platform.claude.com/docs/en/about-claude/pricing · ai.google.dev/gemini-api/docs/pricing ai.google.dev/gemini-api/docs/pricing · api-docs.deepseek.com/quick_start/pricing api-docs.deepseek.com/quick_start/pricing
Trends & comparison
Trend
Comparison (monthly vs. yearly)
AI customer support cost breakdown
A typical customer support interaction uses 800 input tokens (system prompt + conversation history + user message) and generates 300 output tokens (a paragraph-length response). At 50,000 conversations per month, this workload generates 40M input tokens and 15M output tokens monthly. The cost difference between models is dramatic: GPT-5 at $1.25/$10.00 per million tokens costs over $500/month, while GPT-5 Nano at $0.05/$0.40 costs under $10/month for the same volume.
Optimization strategies for support bots
Support bots benefit heavily from Prompt Cache because system prompts and FAQ context are identical across conversations. A 60% cache hit ratio is realistic and cuts input costs by over 50%. Batch API is less useful here since support requires real-time responses. The biggest lever is model selection: most support queries are routine and handled well by smaller models.
Frequently asked questions
Which LLM is cheapest for customer support?▾
For a typical support interaction (800 input + 300 output tokens), DeepSeek V4 Flash and GPT-5 Nano are the cheapest options at under $30/month for 50,000 conversations. Claude Haiku and Gemini Flash-Lite are close alternatives. Quality varies — run a representative eval before switching.
How much does an AI support bot cost per month?▾
At 50,000 conversations/month with 800 input + 300 output tokens each: GPT-5 costs ~$562/month, GPT-5 Mini ~$112, GPT-5 Nano ~$22. Adding Prompt Cache (60% hit) cuts costs by another 40-50%.
Can I use a cheap model for customer support?▾
Yes, for FAQ-style queries and standard responses. Most support interactions are repetitive and well-handled by smaller models. Reserve expensive models for complex escalations via a router.
Compare verified first-party API prices on the same standard workload → AI Model Price Leaderboard