GPT-6 Astra and Claude Fable 5.1 Cost Exactly the Same
Both flagships cost $10 per million input tokens and $50 per million output tokens. One million tokens in plus one million out is $60 either way, so the choice between them is not a price decision.
Every figure here was checked on 16 September 2026 against OpenAI's and Anthropic's own pricing pages. Astra launched 3 to 4 September 2026 and Fable 5.1 landed the same month, so most published comparisons still run on pre-launch rumours.
The matching sticker price is the least interesting fact here. What separates them is the ladder each built underneath, and that is where your bill is decided.
AI Perks tracks $7.7M in credits across 194 companies, the other half of every number below.
GPT-6 Astra vs Claude Opus 5: Opus 5 Is Half the Price
Claude Opus 5 costs $5 input and $25 output per million tokens, exactly half of gpt-6-astra on both sides. Comparing GPT-6 against Opus 5 means comparing OpenAI's current flagship against Anthropic's second tier.
| Model | Input / 1M | Output / 1M | 1M in + 1M out |
|---|---|---|---|
| gpt-6-astra | $10.00 | $50.00 | $60.00 |
| Claude Fable 5.1 | $10.00 | $50.00 | $60.00 |
| Claude Opus 5 | $5.00 | $25.00 | $30.00 |
Combined columns and percentage gaps throughout this article are estimates derived from the listed input and output prices.
That mismatch is the most common error here. Fable 5.1 is Anthropic's Mythos-class top tier and the true opposite number to Astra. Opus 5 sits one rung down, launched 24 July 2026 at the same price as Opus 4.8. AI Perks tracks credits for both.
Both Ladders, Every Current Tier
OpenAI publishes eight current models spanning $1.40 to $60 per million tokens in and out. Anthropic publishes five, spanning $6 to $60. The ceilings match, the floors do not.
| Model | Input / 1M | Output / 1M | 1M in + 1M out |
|---|---|---|---|
| gpt-6-astra, above 200k context | $20.00 | $75.00 | $95.00 |
| gpt-6-astra | $10.00 | $50.00 | $60.00 |
| Claude Fable 5.1 | $10.00 | $50.00 | $60.00 |
| Claude Mythos 5.1 | $10.00 | $50.00 | $60.00 |
| gpt-5.5 | $5.00 | $30.00 | $35.00 |
| Claude Opus 5 | $5.00 | $25.00 | $30.00 |
| gpt-5.6-sol | $4.00 | $20.00 | $24.00 |
| gpt-5.4 | $2.50 | $15.00 | $17.50 |
| gpt-5.6-terra | $2.00 | $12.00 | $14.00 |
| Claude Sonnet 5 | $2.00 | $10.00 | $12.00 |
| Claude Haiku 4.5 | $1.00 | $5.00 | $6.00 |
| Meta Muse Spark 1.1 to 1.3 | $1.25 | $4.25 | $5.50 |
| gpt-5.4-mini | $0.75 | $4.50 | $5.25 |
| gpt-5.4-nano | $0.20 | $1.25 | $1.45 |
| gpt-5.6-luna | $0.20 | $1.20 | $1.40 |
| Meta Muse Spark Contributor | $0.10 | $0.20 | $0.30 |
Claude Mythos 5.1 matches Fable but is limited availability, so Fable is the practical Anthropic ceiling. Meta Muse Image is $0.01 per image, and the Contributor tier is cheap because Meta trains on your prompts and completions.
Two deliberate gaps. xAI Grok token prices are reported inconsistently across sources, so pricing varies by model and the xAI console is the place to read it. Gemini prices were not verified here and are left out rather than guessed.
Where the Two Bets Actually Diverge
OpenAI bets on breadth and a low floor, financed by a long context surcharge and a faster retirement cycle. Anthropic bets on a narrow, flat, stable ladder with no surcharge on record.
OpenAI charges more above 200,000 tokens. A gpt-6-astra request past that threshold costs $20 input and $75 output: $95 per million in and out, 58% more than the standard rate. Anthropic publishes no equivalent long context tier for Fable 5.1, so past 200k the OpenAI request is the pricier one.
Anthropic prices output at exactly five times input on every tier. Fable, Mythos, Opus 5, Sonnet 5 and Haiku 4.5 all hold the 5x multiple. OpenAI's multiples range from 5x on Astra and Sol to 6x on Terra, Luna, gpt-5.5 and gpt-5.4, and 6.25x on gpt-5.4-nano. Switching tiers inside the Claude line rescales your bill cleanly; inside the OpenAI line it changes shape too.
The December retirement is an effective price increase. The legacy gpt-5 line, at $1.25 and $10, shuts down on 10 December 2026. Its nearest current replacement, gpt-5.6-terra at $2 and $12, costs $14 per million in and out against $11.25, roughly 24% more. At the bottom it is sharper: gpt-5-nano at $0.45 combined becomes gpt-5.6-luna at $1.40, about 3.1 times the cost. Budget for that, do not just re-point an endpoint.
Anthropic cancelled a price rise instead of shipping one. Sonnet 5 was scheduled to go from $2 and $10 to $3 and $15 on 1 September 2026. Anthropic's pricing page now states: "The previously scheduled increase to $3/$15 per million input/output tokens on September 1, 2026 will not occur." That is a 33% saving against the budgeted price, and the most under-reported pricing fact of the quarter.
What Each Ladder Costs at Real Monthly Volume
At 10 million input and 2 million output tokens a month, both flagships cost about $200. Route the same traffic properly and the OpenAI ladder lands near $24, the Claude ladder near $38.
| Monthly volume | gpt-6-astra | Claude Fable 5.1 | Claude Opus 5 | Claude Sonnet 5 | gpt-5.6-luna |
|---|---|---|---|---|---|
| 1M in / 200k out | $20 | $20 | $10 | $4 | $0.44 |
| 10M in / 2M out | $200 | $200 | $100 | $40 | $4.40 |
| 100M in / 20M out | $2,000 | $2,000 | $1,000 | $400 | $44 |
Estimates derived from the list prices above, at full rate, no batch or caching discount.
Send 90% of that 10M in / 2M out volume to the cheapest tier and escalate 10%. On OpenAI, Luna handles the bulk for $3.96 and Astra takes $20: roughly $24 a month, an 88% cut. On Anthropic, Haiku 4.5 handles the bulk for $18 and Fable takes $20: roughly $38, an 81% cut.
Same strategy, different result, because the floor matters more than the ceiling. The flagships tie at $60. The cheapest tiers are $1.40 and $6, and that is where most traffic runs.
Which Ladder Fits Your Workload
Pick by workload economics, not by flagship. We have not verified capability benchmarks for these models, so route by cost and confirm quality with your own evals.
High volume, low judgement work such as classification, extraction and routing belongs on the cheapest tier you can tolerate. gpt-5.6-luna at $0.20 and $1.20 is the aggressive choice, Claude Haiku 4.5 at $1 and $5 the safe one.
Production reasoning traffic sits on Claude Sonnet 5 at $2 and $10 or gpt-5.6-terra at $2 and $12. Sonnet 5 is the better value, precisely because of the cancelled increase.
Escalation only is where $10 and $50 belongs, on either provider. A flagship call costs about 43 Luna calls or 10 Haiku calls, so it has to earn that.
Long documents tilt toward Anthropic, since Astra's surcharge starts above 200,000 tokens. AI Perks covers credits for both.
Frequently Asked Questions
Is GPT-6 Astra cheaper than Claude Fable 5.1?
No, they are identical. Both cost $10 per million input tokens and $50 per million output tokens, verified on 16 September 2026 against each vendor's own documentation. One million in plus one million out is $60 either way. The difference appears above 200,000 tokens, where OpenAI charges $20 and $75 and Anthropic publishes no surcharge.
How does GPT-6 Astra compare to Claude Opus 5 on price?
Claude Opus 5 costs $5 input and $25 output per million tokens, exactly half of gpt-6-astra on both sides. A million tokens in and out is $30 on Opus 5 against $60 on Astra. Opus 5 launched 24 July 2026 at the same price as Opus 4.8. AI Perks tracks credits for both providers.
Which provider is cheaper overall, OpenAI or Anthropic?
The flagships tie at $60 per million in and out. Below that, OpenAI goes lower: gpt-5.6-luna is $1.40 combined against Claude Haiku 4.5 at $6, more than four times cheaper. If most of your traffic runs on a small model, the OpenAI ladder wins on price. AI Perks covers credits for both.
Does GPT-6 Astra charge extra for long context?
Yes. Above 200,000 tokens, gpt-6-astra costs $20 per million input and $75 per million output, which works out to $95 for a million in and out, about 58% more than the standard $60 on that arithmetic. Anthropic publishes no equivalent long context tier for Claude Fable 5.1 in the documentation checked on 16 September 2026.
Did Claude Sonnet 5 get more expensive in September 2026?
No. An increase to $3 and $15 per million input and output tokens was scheduled for 1 September 2026 and then cancelled. Anthropic's pricing page states the increase will not occur, so $2 and $10 is now standard rather than introductory. That is a 33% saving against the figure teams budgeted. See AI Perks for credits.
What happens to gpt-5 on 10 December 2026?
The legacy gpt-5, gpt-5-mini and gpt-5-nano API models shut down that day, so nothing new should be built on them. Migration is also a price increase: gpt-5 at $11.25 per million in and out moves to gpt-5.6-terra at $14, roughly 24% more, and gpt-5-nano to gpt-5.6-luna costs about 3.1 times as much.
How to Cover Either Bill With Credits
Provider credits are denominated in dollars, so they offset list prices directly. At the $10 and $50 list price, every $1,000 of credit buys roughly 100 million flagship input tokens or 20 million output tokens on either flagship, and far more once easy work is routed down the ladder.
Tier selection and credit sourcing are one decision: a team running the routed setup above, at $24 to $38 a month, lives on credits for a long time. One defaulting every call to a flagship does not.
AI Perks tracks $7.7M in credits across 194 companies, covering model providers, cloud compute and the tooling around them. Meta is the exception: no startup credit program exists for Muse, so that ladder is cash only.
Two flagships, one price. Let someone else pay it.