# Atlas with OpenAI o3-pro: The $20 / $80 Reasoning Escape Hatch (2026) > OpenAI o3-pro costs $20 per Mtok input and $80 per Mtok output, 10x base o3, on the same 200K context with a 100K max output. OpenAI o3-pro is the June 2025 high effort version of o3, and inside Atlas it is an escape hatch, not a daily driver. OpenAI o3-pro keeps the same 200K token context and 100K max output as base o3, but charges 10x the price at $20 per Mtok input and $80 per Mtok output. What that 10x buys is a substantially larger per request reasoning budget, which is exactly what you want on one genuinely hard problem and exactly what you do not want burning through an interactive agent loop. Atlas lets you switch the active model and provider on the fly, so the right pattern is to select o3-pro deliberately, for one run, then leave. ## Key takeaways - OpenAI o3-pro costs $20 per Mtok input and $80 per Mtok output, exactly 10x base o3 at $2 and $8. - OpenAI o3-pro keeps the same 200K token context and 100K max output as base o3, so the premium buys reasoning budget only. - OpenAI o3-pro is 7.5x cheaper than o1-pro on both sides ($20 versus $150 input, $80 versus $600 output). - Very high latency makes OpenAI o3-pro unusable as a default in an interactive Atlas session. - The 200K context on o3-pro is small next to modern GPT-5 releases at 400K to 1.05M tokens. ## What does the 10x price of OpenAI o3-pro actually buy? OpenAI o3-pro charges $20 per Mtok input and $80 per Mtok output, exactly 10x base o3 at $2 and $8. That 10x is the direct measure of extra reasoning compute per request. Released in June 2025, o3-pro buys thinking budget, not a bigger window or a newer base model. The value proposition of OpenAI o3-pro is unusually legible: same 200K token context, same 100K max output, ten times the price. The delta is per request reasoning budget. In Atlas that means o3-pro is worth reaching for on the one problem where base o3 stalls, a subtle concurrency bug, a proof that keeps almost closing, an architectural tradeoff with real consequences. It is not worth reaching for on the other ninety-nine tasks. Atlas drafts a plan in a read-only plan agent and asks before switching to a build agent, and the disciplined move is to let a cheap model do discovery, then hand o3-pro a pre-scoped question so you are not paying $20 per Mtok to read files. ## Is OpenAI o3-pro cheaper than o1-pro? Yes. OpenAI o3-pro is 7.5x cheaper than o1-pro on input, at $20 versus $150 per Mtok, and 7.5x cheaper on output, at $80 versus $600 per Mtok. Both sit on a 200K context, and o3-pro is the newer June 2025 model, which makes o1-pro hard to justify. Inside the maximum effort tier, OpenAI o3-pro is the sane option. o1-pro charges $150 per Mtok input and $600 per Mtok output for the same 200K token context, while o3-pro delivers the high effort reasoning path at $20 and $80. That is a 7.5x saving on both sides, from a newer model. For Atlas users who occasionally need the heaviest reasoning available in the OpenAI registry, o3-pro is the entry point that does not require a budget conversation. It still is not cheap, and $80 per Mtok output is a number you should look at before you start, but it is an order of magnitude away from the $600 per Mtok that o1-pro asks for the same window. ## Why should you not set OpenAI o3-pro as your default Atlas model? OpenAI o3-pro has very high latency and is unusable as a default in an interactive Atlas session. At $20 per Mtok input and $80 per Mtok output, an agent loop that reads dozens of files before it thinks is spending real money on discovery that a $2 model does just as well. Two things disqualify OpenAI o3-pro as a default. Latency is the first: o3-pro's very high per request thinking time turns an interactive Atlas session into a waiting room. Cost is the second: Atlas's loop is read heavy, and every file read, tool result, and diff flows back as input tokens at $20 per Mtok. The correct configuration keeps o3-pro off the default and reaches for it with /models on a single hard problem. Give it a tight, pre-scoped prompt from the Atlas plan agent so its expensive reasoning budget is spent on the question, not on file discovery, and watch the cost footer, since output bills at $80 per Mtok. ## Does the 200K context on OpenAI o3-pro limit big refactors? OpenAI o3-pro carries a 200K token context, which is small relative to modern GPT-5 releases spanning 400K to 1.05M tokens. For a wide, many file refactor in Atlas, 200K is the binding constraint, and no amount of reasoning budget buys back window size. The 200K token window on OpenAI o3-pro is the same window as base o3, and it does not grow with the price. Against modern GPT-5 releases at 400K to 1.05M tokens, that is a real gap. Atlas softens it: Atlas indexes code by AST declarations using tree-sitter, not blind line windows, and searches code with hybrid semantic and keyword retrieval fused by reciprocal rank fusion, so the 200K you do get is filled with whole declarations rather than noise. On the output side o3-pro is generous, with 100K max output, so a long derivation or a complete design document fits in one response. But breadth across a huge repository is not what o3-pro is for. ## When should you pick a different model instead of OpenAI o3-pro? Pick base o3 instead of OpenAI o3-pro whenever the problem is not exceptionally hard, since o3 delivers the same 200K context and 100K max output at $2 in and $8 out, one tenth the price. Reserve o3-pro for the single problem that base o3 could not close. The decision rule for OpenAI o3-pro is a price-per-solved-task question. If base o3 solves the problem, the 10x premium bought nothing, and you paid $20 per Mtok input for an answer available at $2. If base o3 stalls, o3-pro's larger per request reasoning budget is the reason it exists. Anything that needs a very large context or fast turns belongs on a different model entirely, since o3-pro fixes neither. Atlas lets you switch the active model and provider on the fly with favorites and recents, which makes the escalate-and-return pattern cheap to execute: run on something normal, escalate for one turn, come back. ## Setup 1. Export OPENAI_API_KEY in your shell or store it in Atlas's credential store. 2. Run `atlas models openai` and check that o3-pro appears in the resolved model list. 3. Keep OpenAI o3-pro off the default: switch to it with /models only for a single hard problem. 4. Give o3-pro a tight, pre-scoped prompt from the Atlas plan agent so you are not paying $20 per Mtok for file discovery. 5. Watch the cost footer during the run, since output bills at $80 per Mtok. ## FAQ ### How much does OpenAI o3-pro cost per million tokens? OpenAI o3-pro costs $20 per Mtok input and $80 per Mtok output. That is 10x the price of base o3, which charges $2 input and $8 output for the same 200K context. ### What is the difference between o3 and o3-pro? OpenAI o3-pro is the June 2025 high effort version of o3. Same 200K token context and 100K max output, but 10x the price, buying a substantially larger per request reasoning budget. ### Is OpenAI o3-pro worth it for coding? OpenAI o3-pro is worth it only for a single hard problem that base o3 could not close. Its very high latency makes it unusable as an interactive default in Atlas. ### What is the context window of OpenAI o3-pro? OpenAI o3-pro has a 200K token context with a 100K max output. That is small relative to modern GPT-5 releases, which span 400K to 1.05M tokens. ### How do I switch to OpenAI o3-pro in Atlas? Export OPENAI_API_KEY, run `atlas models openai` to check o3-pro resolved, then use /models in the Atlas TUI to switch to it for one run instead of pinning it as a default. ### Is o3-pro cheaper than o1-pro? Yes. OpenAI o3-pro is 7.5x cheaper than o1-pro on input at $20 versus $150 per Mtok, and 7.5x cheaper on output at $80 versus $600 per Mtok. ### How do I avoid a surprise bill running o3-pro in an agent loop? Pre-scope the prompt with the Atlas plan agent so o3-pro is not doing file discovery at $20 per Mtok input, and watch the cost footer, since output bills at $80 per Mtok. --- Canonical HTML: https://runatlas.sh/resources/models/o3-pro Source of truth: aeo_pages row `/resources/models/o3-pro` (segment: Models) (this file is generated from it, never hand-edited). Licence: Atlas is proprietary with a free core. It is not open source and there is no public source repository.