It started with a simple question: is there any high-end AI service that ordinary users can actually access without paying a fortune?
Then GPT-6 Astra showed up in GMO Tenbin AI’s model picker.
Seeing it in a menu was not enough. Plenty of apps put shiny treasure chests on the screen and reveal the paywall only after you click.
So the model was selected.
It worked.
That immediately changed the question from “Is Astra really available?” to “How should I spend this absurdly good free allowance?”
For data analysis, there is one catch: the Free plan is not a convenient place to dump enormous raw datasets. That sounds like a weakness, but it becomes much less important if Astra is used as a research director rather than the machine that scans every raw row.
1. The five-second answer: free, two Astra calls per day, reset at midnight
GMO Tenbin AI’s official information states that the personal Free plan receives 80 credits per day, and Plus also receives 80. Credits reset at 00:00 every day.[1]
GPT-6 Astra is listed as a specialist model costing 40 credits per use.[1][2]
So the math is pleasantly boring:
| Item | Amount |
|---|---|
| Free plan | ¥0 |
| Daily credits | 80 |
| Astra per request | 40 |
| Maximum Astra requests | 2/day |
| Reset | 00:00 daily |
| Free chat input | 10,000 characters/request |
| Plus | ¥970/month incl. tax |
| Plus daily AI credits | 80 |
| Plus chat input | 50,000 characters/request |
That is effectively two free Astra shots every day, with ammunition restored at midnight — but each Free shot has a 10,000-character loading gate.
If other credit-consuming models are used, those credits come out of the same daily pool. Running multiple selected AIs at once adds their costs together.[1]
The model-selection screen may look like an all-you-can-eat buffet. The credit meter remembers that food still has calories.
2. Does Plus give you more Astra? No
This is the easy place to waste money for the wrong reason.
Free costs nothing. Plus costs ¥970 per month. Yet both personal plans receive the same 80 AI credits per day.[1][3]
So upgrading does not turn two Astra requests into four.
Plus mainly adds capabilities around the model: Web search, file uploads, Deep Research, image functions, more history, and a larger chat-input cap of 50,000 characters instead of 10,000.[1][3]
That means the correct distinction is:
Do not buy Plus to increase Astra quantity. Buy Plus only if you need better ways to feed information into Astra or use the surrounding tools.
3. Astra itself is huge: a 1.05-million-token context window
OpenAI lists GPT-6 Astra with a 1,050,000-token context window and up to 128,000 output tokens.[4]
It is positioned for difficult end-to-end work involving reasoning, coding, research, computer use and document creation.[4][5]
Tenbin AI similarly describes Astra as a top-tier model for long context and multi-step work.[1][2]
At this point the data analyst’s inner goblin says: “One million tokens? Great. Feed it everything.”
Not so fast.
A model’s theoretical capacity and the service interface around that model are different layers.
A Formula 1 engine does not make your apartment door wider.
4. The biggest Free-plan limitation: it cannot directly ingest your giant source files
Tenbin AI Free does not support file attachments.[1]
That means it is not a natural interface for dropping in huge CSV, JSON, Parquet, log or tick-data files and asking Astra to search everything.
There is another hard gate: the Free chat text box accepts 10,000 characters per message, and text beyond that limit is automatically cut. Plus allows 50,000 characters.[1][3]
This is crucial: Astra’s 1.05-million-token context is a model capability; Tenbin AI Free’s 10,000-character ceiling is a service/input limit. They are not the same limit.
So on Free, the final research packet — instructions, exploration history, summarized evidence and failed hypotheses — must be compressed to 10,000 characters or less in total. If the tail gets automatically cut, the missing part could be exactly where the falsification criteria or failure history lived.
The brain is stadium-sized. The reception desk takes 10,000 characters. Compress before delivery.
Plus supports uploads, but the service still has practical upload limits: up to five files at once, 32 MB limits for several document types, and 100,000-character limits for many text/data formats such as CSV, JSON and TXT.[3]
So even with Plus, multi-gigabyte raw datasets belong somewhere else.
The model may have a giant brain. The front door is still a front door.
5. Does that make Astra bad for data analysis? No — change its job
Large-scale analysis does not require an LLM to personally inspect every raw record.
Let Python, SQL, a backtesting engine, cloud compute, local code or a coding agent handle the data where it actually lives.
Then return compressed evidence such as:
- results by market, period or condition;
- best and worst cases;
- outliers;
- failed hypotheses;
- parameter sensitivity;
- regime or time-of-day differences;
- results after fees and slippage;
- train/validation/out-of-sample gaps;
- important code decisions;
- unresolved branches.
On Free, compress that final packet again so the prompt plus evidence stays within 10,000 characters.[1]
Give that to Astra.
Now Astra’s job is not “perform every calculation.” It is decide which calculation deserves to happen next.
Congratulations, Astra-kun. You have been promoted from the server room to the research director’s chair.
6. Turn “cannot touch all raw data” into a research design constraint
The main danger in exploratory analysis is often not model intelligence. It is process decay.
People and AIs can repeatedly rename the same hypothesis, focus on the lucky period, add costs only after seeing profits, add too many variables, forget failed tests or call overfitting a discovery.
Separating execution from research design can help.
The execution system runs a fixed specification over the full data.
Astra reviews the evidence, proposes hypotheses, defines falsification tests and writes the next experiment specification.
The 10,000-character cap also forces compression. That compression must not keep only the winners: failed cases, exclusions, tested ranges and evidence needed for falsification deserve space before decorative detail.
In other words: do not give the research director an unrestricted SQL console; make the director work from a sub-10,000-character experiment report and request.
It is less convenient, but sometimes more scientifically disciplined.
7. A strong way to spend the two free Astra calls
Shot 1: the research meeting
Before pasting the summarized experimental record, make the whole Free-plan message — instructions included — fit within 10,000 characters. A useful compression order is: objective, verified facts, failed hypotheses, falsifying evidence, open branches, then the decision you want Astra to make.[1]
Ask Astra to separate verified findings, untested hypotheses and failed hypotheses. Tell it to prioritize possible overfitting, leakage, costs, temporal dependence and regime dependence, then rank only the three next experiments worth running.
The goal is not “give me 100 clever ideas.”
The goal is delete 97 ideas and keep the three that deserve compute.
Shot 2: turn the winner into an executable specification
Ask Astra to convert the top experiment into instructions that another coding or compute environment can execute directly: inputs, scope, exclusions, features, metrics, fees, slippage, time-series splits, leakage controls, success and failure criteria, intermediate outputs, reproducibility checks and stopping conditions.
Now the two calls form a clean loop:
think → issue an experiment order.
That is an excellent use of a scarce high-end model.
8. Midnight reset enables a legal four-shot combo
Credits reset to 80 at midnight.[1]
So you can spend the current day’s remaining allowance shortly before midnight and use the next day’s allowance right after midnight.
For example:
23:50 — research review
23:58 — experiment specification
00:05 — review new results
00:15 — next specification
That is a perfectly legal date-boundary four-hit combo.
It is not free energy; you are spending tomorrow’s allowance. But for one concentrated late-night research session, the timing is useful.
9. The multi-model picker is glorious, but credits still add up
Tenbin AI can send the same question to multiple models and compare answers.[1]
Seeing Astra sitting beside other flagship models feels like a character-select screen where half the roster is legendary rarity.
But simultaneous selections consume the sum of all model costs.
If you want to devote the whole free 80-credit pool to two Astra calls, avoid casually burning credits on expensive comparison models first.
A cheap model can preprocess or summarize; Astra can take the difficult final judgment.
Do not summon the final boss to rename CSV columns.
10. “Same Astra model” does not mean “same product environment”
OpenAI uses Astra across environments such as ChatGPT Work, Codex and GPT-6 Pro for eligible plans, where the model may have access to files, apps, browsers, computer use and other product capabilities.[5][6]
Selecting Astra inside Tenbin AI means you are using Astra, but it does not recreate the entire ChatGPT product environment, memory system, connectors, tools or usage rules.
Same engine, different vehicle and toolbox.
For serious data work, this distinction matters as much as raw model quality.
11. Conclusion: free Astra is best seen as a twice-daily research director
The useful summary is simple:
- Free: 80 credits/day.
- Astra: 40 credits/request.
- Maximum: 2 Astra requests/day.
- Reset: midnight every day.
- Free chat input: 10,000 characters/request; overflow is automatically cut.
- Plus chat input: 50,000 characters/request.
- Plus still has 80 daily AI credits.
- Free has no file upload or Web search.
- Process giant raw datasets elsewhere.
- Give Astra compact results, failures and code summaries with prompt + evidence kept under 10,000 characters on Free.
- Use Astra for hypotheses, falsification, prioritization and next-step instructions.
The limitation is real, but it does not kill the use case.
It changes the question from “Can Astra read everything?” to “Given what we already learned, what should we test next?”
That is often the better research question anyway.
Free Astra is not your data center.
It is the frighteningly smart research director who appears in the meeting room twice a day — and the meeting packet has to fit within 10,000 characters.
Sources
- GMO天秤AI「よくある質問と回答」 — Free/Plusの1日80クレジット、0時リセット、複数AIの消費合算、Freeのファイル添付非対応、モデル別消費クレジット、Freeチャット入力10,000文字、Plus 50,000文字、超過分の自動カット。確認日: 2026-09-12 help.tenbin.ai
- GMO天秤AI「チャット機能」 — GPT-6 Astraを専門40クレジットの利用可能モデルとして掲載。個人向けチャット入力10,000文字、超過分自動カットも明記。確認日: 2026-09-12 help.tenbin.ai
- GMO天秤AI「Plusプランについて」および法人FAQの個人プラン比較 — Plus 970円/月、Web検索・ファイル添付、チャット入力50,000文字、ファイル形式/サイズ上限など。確認日: 2026-09-12. ; https://help.tenbin.ai/biz/faq/ help.tenbin.ai
- OpenAI API Docs, “GPT-6 Astra Model” — 1,050,000 context window、128,000 max output tokens、用途。確認日: 2026-09-12 developers.openai.com
- OpenAI Release Notes, “Introducing GPT-6 Astra,” 2026-09-03 — coding、research、computer use、complex multi-step work。 openai.com
- OpenAI Help Center, “ChatGPT Work and Codex” / Astra usage guidance — ChatGPT Work、Codex、GPT-6 ProにおけるAstraの提供形態。確認日: 2026-09-12. ; https://help.openai.com/en/articles/20001516-managing-usage-with-gpt-6-astra-in-work-and-codex help.openai.com
