Cheaper alternatives to GPT-6 Astra
GPT-6 Astra costs $10 / $50 per 1M input / output tokens and scores 169 on Epoch AI’s Capabilities Index. 5 current models score within its margin of error for less, the cheapest being GPT-6.1 Terra at 90% less. Prices checked 13 Oct – 6 Nov 2026.
Similar capability, lower price
Highest score first
| Model | Capability | Input / output per 1M | Cheaper by | Customer chat assistant, a month | Compare |
|---|---|---|---|---|---|
 GPT-6.1 TerraOpenAI |
168level, within the margin | $1.00 / $5.00 | 90% | $153 | Compare |
| GPT-6.1 SolOpenAI |
168level, within the margin | $2.00 / $10.00 | 80% | $305 | Compare |
 Claude Opus 5.5Anthropic |
168level, within the margin | $4.00 / $20.00 | 60% | $610 | Compare |
| Claude Sonnet 5.5Anthropic |
167level, within the margin | $2.00 / $10.00 | 80% | $305 | Compare |
 Gemini 4 ArgonGoogle |
166level, within the margin | $2.00 / $10.00 | 80% | $305 | Compare |
A step down, for much less
Highest score first
| Model | Capability | Input / output per 1M | Cheaper by | Customer chat assistant, a month | Compare |
|---|---|---|---|---|---|
| Claude Haiku 5.5Anthropic |
1609 below | $0.10 / $0.50 | 99% | $15.50 | Compare |
| Gemini 3.8 FlashGoogle |
15811 below | $0.75 / $3.75 | 93% | $116 | Compare |
 Qwen3.8 MaxAlibaba |
15811 below | $2.00 / $6.00 | 85% | $320 | Compare |
 Kimi K3Moonshot AI · open weights |
15811 below | $3.00 / $15.00 | 70% | $465 | Compare |
| GPT-6 LunaOpenAI |
15712 below | $0.10 / $0.50 | 99% | $15.50 | Compare |
 Muse Spark 1.3Meta |
15712 below | $1.25 / $4.25 | 90% | $155 | Compare |
Other frontier models, not yet scored
| Model | Capability | Input / output per 1M | Cheaper by | Customer chat assistant, a month | Compare |
|---|---|---|---|---|---|
| Kimi K3.1 ProMoonshot AI |
Not scored | $2.00 / $10.00 | 80% | $310 | Compare |
What switching saves on three workloads
Per month, list prices
| Workload | GPT-6 Astra | GPT-6.1 Terra | GPT-6.1 Sol | Claude Haiku 5.5 |
|---|---|---|---|---|
| Customer chat assistant100M in, 20M out, 50% cached | $1,550 | $153 | $305 | $15.50 |
| Document Q&A (RAG)240M in, 12M out, 30% cached | $2,352 | $232 | $463 | $23.52 |
| Coding agent750M in, 8M out, 85% cached | $2,163 | $184 | $369 | $21.63 |
Monthly cost at list prices with no batch discount. Your own numbers: open these models in the cost calculator.
How to choose
- Same quality, smaller bill: GPT-6.1 Terra scores level with GPT-6 Astra and costs 90% less. Test it on your hardest prompts first.
- Stay with OpenAI: GPT-6.1 Sol keeps the same API, tools and data terms at $2 / $10.
- Mix models: send routine requests to a cheaper model and keep GPT-6 Astra for the hard ones. How much that saves depends on your traffic, so measure quality on a sample before switching everything.
- Cut the bill without switching: batch processing and prompt caching often save more than changing model. See how to cut your API bill in half.
Questions
What is the cheapest alternative to GPT-6 Astra with similar capability?
GPT-6.1 Terra from OpenAI, at $1 / $5 per 1M input / output tokens, 90% less than GPT-6 Astra at a typical 3:1 mix. On Epoch AI’s Capabilities Index it scores 168 against 169, within the margin of error.
Is GPT-6.1 Terra as good as GPT-6 Astra?
On general benchmarks, they’re level: Epoch AI’s Capabilities Index gives GPT-6.1 Terra 168 (range 165–173) and GPT-6 Astra 169 (166–174). Benchmarks don’t cover every task, so run both on a sample of your own work before switching.
How much would I save by switching from GPT-6 Astra?
For a customer chat assistant (100M input and 20M output tokens a month, half the input cached), GPT-6 Astra costs $1,550 a month. GPT-6.1 Terra costs $153, GPT-6.1 Sol $305.
Is there a cheaper OpenAI model than GPT-6 Astra?
Yes: GPT-6.1 Sol ($2 / $10, capability 168), GPT-6.1 Terra ($1 / $5, capability 168), GPT-6 Luna ($0.10 / $0.50, capability 157). Staying with OpenAI keeps your prompts, tools and billing the same.
Why isn’t every cheaper model listed?
We list current models that cost less than GPT-6 Astra at a 3:1 input-to-output mix and either score within about 12 points of it on Epoch AI’s index or are in the same tier without a score yet. Much weaker models are cheaper still but rarely a like-for-like swap.
Capability: Epoch Capabilities Index by Epoch AI, CC BY 4.0, read 4 Nov 2026. Prices from each provider’s own page, linked on every model page.