Best LLMs for Customer Support: Fast, Cheap Models Compared

Support bots answer similar questions all day, so cost per conversation and response time matter more than peak intelligence. A 30,000-conversation month can cost a few dollars or a few hundred depending on the model.

Accuracy comes mostly from grounding: retrieving the right help-center articles and policies and instructing the model to answer only from them. Pair a fast model for routine questions with a stronger one for escalations.

The shortlist

Model	Tier	Weights	Context	Input / 1M	Output / 1M	Inputs
NVIDIA Nemotron 3.5 Lightning 30B-A3BNVIDIA	Compact	Open weights	1M	$0.05	$0.20	Text
Ministral 3 3BMistral AI	Compact	Open weights	256K	$0.10	$0.10	Text, Images
Granite 4.2 8BIBM	Compact	Open weights	128K	$0.06	$0.25	Text
gpt-oss-20bOpenAI	Compact	Open weights	128K	$0.075	$0.30	Text
Gemma 4 26B A4BGoogle	Compact	Open weights	256K	$0.07	$0.34	Text, Images, Video
Ministral 3 8BMistral AI	Compact	Open weights	256K	$0.15	$0.15	Text, Images
Claude Haiku 5.5Anthropic	Efficient	Closed	1M	$0.10	$0.50	Text, Images, PDF
GPT-6 LunaOpenAI	Efficient	Closed	1.05M	$0.10	$0.50	Text, Images
GLM-5.3-FlashZ.ai (Zhipu AI)	Efficient	Open weights	1M	$0.15	$0.50	Text, Images, Video
Gemma 4 31BGoogle	Efficient	Open weights	256K	$0.20	$0.40	Text, Images, Video
Mistral Small 4Mistral AI	Efficient	Open weights	256K	$0.15	$0.60	Text, Images
gpt-oss-120bOpenAI	Advanced	Open weights	128K	$0.15	$0.60	Text
Qwen3.6-35B-A3BAlibaba (Qwen)	Compact	Open weights	256K	$0.10	$0.95	Text, Images, Video
Codestral 25.08Mistral AI	Efficient	Closed	125K	$0.30	$0.90	Text
DeepSeek-V4.1-FlashDeepSeek	Advanced	Open weights	1M	$0.30	$1.20	Text, Images
MiniMax-M3MiniMax	Advanced	Open weights	1M	$0.30	$1.20	Text, Images, Video
Gemini 3.1 Flash-LiteGoogle	Efficient	Closed	1M	$0.25	$1.50	Text, Images, Video, Audio, PDF
SonarPerplexity	Efficient	Closed	—	$0.25	$2.50	Text
Gemini 3.5 Flash-LiteGoogle	Efficient	Closed	1M	$0.30	$2.50	Text, Images, Video, Audio, PDF
Grok Build 0.1xAI	Efficient	Closed	250K	$1	$2	Text, Images
Gemini 3.8 FlashGoogle	Advanced	Closed	1M	$0.75	$3.75	Text, Images, Video, Audio, PDF
Gemini 3.6 FlashGoogle	Advanced	Closed	1M	$0.75	$3.75	Text, Images, Video, Audio, PDF
Grok 4.3xAI	Efficient	Closed	1M	$1.25	$2.50	Text, Images
Claude Sonnet 5.5Anthropic	Advanced	Closed	1M	$2	$10	Text, Images, PDF
Amazon Nova 2 LiteAmazon (AWS)	Efficient	Closed	1M	—	—	Text, Images, Video, PDF
Gemma 4 E4BGoogle	Compact	Open weights	128K	—	—	Text, Images, Audio, Video
Phi-4-mini-instructMicrosoft (Phi)	Compact	Open weights	128K	—	—	Text

Ordered by status, capability tier and then price. Tiers are our editorial grouping of provider positioning and public benchmark standings, not our own test results. How we rank.

How to choose

Ground answers in your knowledge base with retrieval and citations; see RAG explained.
Keep humans in the loop for refunds, legal and safety questions.
Measure resolution rate and escalation rate, not just cost.
Watch for prompt injection from customer messages; see LLM security.

Frequently asked questions

Which LLM is best for customer service?

Usually a fast, inexpensive model grounded in your own help content, with escalation to a stronger model or a human for complex cases. Start with the efficient models in this list and compare resolution rates on a sample of real tickets.

How much does an AI support bot cost to run?

At list prices, a month of 30,000 conversations with about 2,000 input and 400 output tokens each costs from a few dollars on the cheapest models to a few hundred on frontier models. The calculator works it out for your volumes.

Other shortlists

Coding Agents Long documents Cheapest APIs Longest context Open weights Run locally Multimodal Reasoning

Need hands-on help building it?

RAG, agents, fine-tuning or a production chatbot: describe the project and we'll suggest an approach and, if you want, partners who build it.

Free and vendor-neutral: no model provider pays for placement.
Your details go only to partners you agree to.