GPT-3.5 Turbo (Instruct)
GPT-3.5 Turbo (Instruct) is worth evaluating for classification and json / tool use when its provider route and context window match the workload.
Use it for
- Teams evaluating classification and json / tool use
- Workloads that can use a 4k context window
- Buyers comparing 4 tracked provider routes
Do not use it for
- Vision or document-understanding workloads
- Family
- GPT-3.5
- Released
- 2023-09-19
- Context
- 4k
- Parameters
- 20B
- Architecture
- Decoder Only
- Knowledge cutoff
- 2021-09
- Specialization
- general
- Openness
- Proprietary
- License
- ProprietaryCommercial use: conditional
- Weights
- Not released
- Code
- Unknown
- Training
- Fine-tuned
Cheapest of 5 routes · OpenAI API
About
GPT-3.5 Turbo Instruct by OpenAI is designed to excel in precise instruction following and task completion, focusing on accuracy and clarity over conversational abilities. It offers key enhancements like efficient instruction adherence, reduced hallucination, and lower toxicity compared to previous models. Compatible with legacy completion endpoints, it retains the speed and affordability of the standard GPT-3.5 Turbo model while using a 4K context window and training data up to September 2021. Not specifically built for chat, it still supports diverse tasks like question answering, text completion, and code generation, aiming to enhance AI usability with safer and more accurate interactions.
GPT-3.5 Turbo Instruct is OpenAI's instruction-tuned model designed for the legacy completions endpoint, released in September 2023. Unlike the GPT-3.5 Turbo Chat family which uses the messages API format, this variant takes a single prompt string and returns a completion—the interface used by older text-davinci and code-davinci models. It is OpenAI's recommended migration target for applications using those deprecated legacy completions models. The context window is 4,096 tokens and training data has a knowledge cutoff of September 2021.
The model is optimized for precise task completion given explicit prompts: structured extraction, constrained text generation, question answering with a fixed format, and batch-style tasks that do not require multi-turn dialogue. It exhibits lower hallucination rates and better instruction adherence than older GPT-3 completion models. The model does not natively support the chat messages format, though it can be used to simulate multi-turn conversation by including prior turns in the prompt string.
GPT-3.5 Turbo Instruct is available through the OpenAI API, Azure OpenAI Service (ai.azure.com), OpenRouter, and the Vercel AI Gateway. The 4K context window and completion-endpoint format limit its utility for modern multi-turn or long-context applications; GPT-4o mini or a Claude Haiku model covers most equivalent use cases with longer context and chat-optimized interfaces.
GPT-3.5 Turbo (Instruct) has a 4k-token context window.
GPT-3.5 Turbo (Instruct) input tokens at $1.5/1M, output at $2/1M.
Top use-case fit
Classification
Included by capability and metadata signals in the decision map.
JSON / Tool use
Included by capability and metadata signals in the decision map.
Provider price ladder
Compare all 5Compare API pricing across 4 providers for input and output tokens, batch, and cached reads when available.
| Provider | Input / 1M | Output / 1M | Batch in / out | Route |
|---|---|---|---|---|
| OpenAI API | $1.50 | $2.00 | $0.750 / $1.00 | Serverless |
| OpenRouter | $1.50 | $2.00 | - | Serverless |
| Vercel AI Gateway | $1.50 | $2.00 | - | Serverless |
| Salesforce Einstein Generative AI | - | - | - | ServerlessPartial |
Available via routers & gateways(16)
LiteLLM
GatewayOpen-source Python SDK and proxy server that unifies 100+ LLM APIs behind a single OpenAI-compatible interface, with load balancing, cost tracking, and configurable failover.
OpenRouter
HybridUnified hybrid gateway to 400+ models from 60+ providers via a single OpenAI-compatible API, with optional auto-routing that selects the best model per prompt.
Portkey
GatewayProduction AI gateway routing to 1,600+ LLMs with failover, load balancing, semantic caching, and guardrails; Apache 2.0 core is fully self-hostable with the complete feature set.
AIRouter
RouterCommercial LLM router that analyzes incoming requests and routes to the optimal model for cost/quality/latency via a drop-in OpenAI-compatible API, with a privacy-preserving embedding mode that avoids sending prompt content.
Azure AI Foundry Model Router
RouterMicrosoft Azure AI Foundry's native model router that uses a trained ML model to route each prompt in real time to the optimal Azure-hosted model, with Balanced/Cost/Quality mode selection and automatic failover.
Helicone
GatewayObservability-first AI gateway with routing, caching, rate limiting, and request tracing; Apache 2.0 open-source core with a managed hosted tier for logging and analytics.
Capabilities
Benchmark peer barsfor Classification
No task-mapped benchmark peers are available for this model yet.
Migration checks
No linked migration route is available for this model yet.
API versions
gpt-3.5-turbo-instructFrequently asked questions
What is the context window of GPT-3.5 Turbo (Instruct)?
GPT-3.5 Turbo (Instruct) has a context window of 4k tokens.
How much does GPT-3.5 Turbo (Instruct) cost?
GPT-3.5 Turbo (Instruct) is available at $1.5/1M input tokens through Azure OpenAI.
When was GPT-3.5 Turbo (Instruct) released?
GPT-3.5 Turbo (Instruct) was released on 2023-09-19.
Which providers offer GPT-3.5 Turbo (Instruct)?
GPT-3.5 Turbo (Instruct) is available from 5 providers: Azure OpenAI, OpenAI API, Salesforce Einstein Generative AI, OpenRouter, Vercel AI Gateway.
Cheapest of 5 routes · OpenAI API