Codex vs Claude Code: Quality Against Cost

Updated: 6 November 2026

In Codex vs Claude Code there is no clear winner: Codex with GPT-6.1 Sol costs less per solved task, and Claude Code with Opus 5.5 solves more tasks. So whether to pick Codex or Claude Code depends on how you pay and what rework costs you. On Terminal-Bench 4.0 (read 6 November 2026), an independent test that gives coding agents tasks to complete in a computer's terminal, Claude Code running Anthropic's Opus 5.5 solved about 7 more tasks in 100 than Codex running OpenAI's GPT-6.1 Sol. Codex with GPT-6.1 Sol cost about a seventh as much per solved task: $3.30 against $22.05. Both ran at maximum reasoning effort.

The cost gap shows on your bill only when you pay per use: through an API key (a company account billed for every token), or for use past a seat's allowance; on a seat it shows as how fast the allowance runs out. Team seats (Codex Business, Claude Team Standard) cost the same at both vendors: $20–25 per user a month at 6 November 2026 list prices.

If you buy Codex or Claude Code seats, look at the team-seat row; if you pay per use, look at the cost-per-solved-task row. Seats cost the same at both vendors, so, when buying seats, pick whichever of the two your trial shows solves more and runs out of its allowance less often.

Contents

• Codex vs Claude Code on an independent test
• What Codex and Claude Code cost: per seat or per use
• Training models on your code: the terms at OpenAI and Anthropic
• Using Codex and Claude Code together, or switching later
• How to choose between Codex and Claude Code: a two-week trial
• Sources
• FAQ

Codex vs Claude Code on an independent test

Terminal-Bench 4.0 publishes a leaderboard (below, "the board") of coding agents, each paired with a model. Each score comes from 330 attempts. The board also shows what each run cost in model fees (its "bills") and how many tokens it used. Tokens are the pieces of text a model reads and writes, and both vendors bill by them; each vendor counts them its own way, so the counts compare roughly. Cost per solved task is a run's whole bill divided by the tasks it solved, so the failed attempts are paid for too.

The four rows that matter here, read on 6 November 2026, all at maximum reasoning effort:

The 95% range is the spread the board gives around each score. Claude Code with Opus 5.5 solved about 7 more tasks in 100 than Codex with GPT-6.1 Sol, and the lead is narrow. On the board's own ranges the two only just separate. A plain count of 330 attempts would give wider ranges, about ±5 points, and those overlap. Read it as a likely lead of a few points, not a settled one. The board detail is in our alternatives guide.

Maximum reasoning effort is a setting, not the default — it lets the model think longer before it acts. OpenAI's API default for GPT-6.1 Sol is medium. Higher effort usually scores more and costs more, though not always: for Opus 5, the board's xhigh run beat its max run on both score and cost. For the pairs above, Terminal-Bench 4.0 lists maximum-effort runs only.

Why not to judge Codex and Claude Code by the price list

Anthropic's Sonnet 5.5 and OpenAI's GPT-6.1 Sol have the same list price: $2 per million tokens in and $10 per million out. Yet on Terminal-Bench 4.0 (6 November 2026, maximum effort), Claude Code with Sonnet 5.5 cost about 11 times as much per solved task as Codex with GPT-6.1 Sol ($35.95 against $3.30). The difference is tokens — 95.2 million per solved task against 7.6 million.

Opus 5.5 costs twice as much per token as GPT-6.1 Sol ($4 in, $20 out) and, in Claude Code, used about 4.9 times as many tokens per solved task. Multiplied, those would make a gap of about 10× — the bills show about 6.7×. Our reading of the board's token counts: most of the extra tokens were context the agent sends back to the model at every step, which both vendors bill as cache reads at a twentieth of the input price. Of the tokens it wrote, billed at the full output price, it used only about twice as many as GPT-6.1 Sol.

The 1/7 belongs to GPT-6.1 Sol, not to Codex as such: with GPT-6 Astra, Codex scored the same 58.2% at $17.02 per solved task, about five times as much and closer to Claude Code with Opus 5.5 ($22.05).

How much a task costs depends on the model and on the tool it runs in. In a published test by Composio (18 August 2026, one author), the same open model, DeepSeek V4 Flash, solved 16 of 30 hard multi-app tasks in each tool. Composio estimated $0.195 per solved task in Claude Code and $0.081 in Codex, with Claude Code finishing about twice as fast. On the same page, Composio also compared newer models from both vendors on another benchmark, DeepSwe: Anthropic's Fable 5 and OpenAI's GPT-5.6 Sol, both at high reasoning effort, reached the same 69% pass rate at $9.18 against $3.47 per task, about 2.6 times, a smaller gap than the board's 6.7×.

It is hard to judge in advance how either tool will do on your code and your tasks, and how much rework it will leave. A two-week trial (under "How to choose between Codex and Claude Code", below) can show that.

What your developers will compare between Codex and Claude Code

Both tools run on the developer's own computer and send prompts and code to the vendor's servers, where the model runs. Both can also run tasks on the vendor's machines instead: Codex cloud at OpenAI (off by default for Enterprise workspaces) and cloud sessions at Anthropic. Your developers will also be able to compare speed and how each tool fits their editor; the trial is where they judge both.

What Codex and Claude Code cost: per seat or per use

The short version. Team seats for Codex and Claude Code cost the same. Terminal-Bench 4.0's cost gap turns into money when you pay per use — by API key, or for use past a seat's allowance.

On seats, the price is the same. Codex Business and Claude Team Standard both cost $20 per user a month on an annual plan and $25 on a monthly one. Both seats include the models on the board: OpenAI's allowance table for Business lists GPT-6.1 Sol, and Claude Team includes Opus. A seat buys an allowance of use, and neither vendor publishes how much work an allowance covers in tasks. OpenAI gives a range for Plus and Business, 15–160 local messages per five hours with GPT-6.1 Sol, and adds that "these estimates are not fixed message limits". Anthropic says a Team Standard seat gives "more usage than Pro".

Our inference: Claude Code with Opus 5.5 cost about 6.7 times as much per solved task as Codex with GPT-6.1 Sol on Terminal-Bench 4.0 (6 November 2026, maximum effort), so on a seat it probably also uses up the allowance faster. Your trial will show how much that matters: count how often each developer hits the limit.

Per use, the gap can be significant. Only one route prices both sides at published rates — an API key against an API key. On Claude's side, Enterprise usage and usage credits past a seat's allowance are also billed at API rates. Codex use past a plan's allowance is paid in ChatGPT credits, and OpenAI says credit prices "depend on your plan or agreement", so there is no public dollar rate to compare. Terminal-Bench doesn't say which prices its bills use.

A budget model, with inputs rather than a forecast:

• Seats: the number of developers × $20–25 a month (Codex Business or Claude Team Standard, vendor list, 6 November 2026) — the same at both vendors.
• Anthropic's own average for Claude Code: about $150–250 per developer a month across enterprise deployments (read 21 October 2026). OpenAI publishes no equivalent figure for Codex.
• Terminal-Bench 4.0's bills (6 November 2026, maximum effort): 100 attempted tasks cost about $1,430 with Claude Code and Opus 5.5 and about $192 with Codex and GPT-6.1 Sol. These are one benchmark's bills, not a projection of yours.
• Your trial's costs: what your own tasks cost on each tool; budget on these.

The average is per developer a month and the benchmark's bills are per task, so neither can be worked out from the other. For a worked budget, see a ten-developer example for Claude Code in our Claude Code for business guide.

Training models on your code: the terms at OpenAI and Anthropic

The short answer. On company plans, neither OpenAI nor Anthropic trains its models on your code by default. On personal plans, training is a setting each employee controls at both vendors: OpenAI says it is on by default, and Anthropic lists it as opt-out. Codex adds a second switch of its own.

Both vendors have admin tools: basic ones on the team plans, extended ones on Enterprise. Codex Business comes with "essential admin controls, SAML SSO, and MFA"; Enterprise adds automatic user provisioning (SCIM), role-based access, audit logs through the Compliance API, and data retention and residency controls. Claude Team includes single sign-on, domain verification, central billing and spend controls; Claude Enterprise adds SCIM, role-based access and audit logs.

The rule: buy the company plan, and don't let staff bring personal accounts to company code. On a personal plan, the vendor's training terms depend on a switch each employee controls — and with Codex, on two switches. If a contractor writes your code, ask which plan its developers use. Claude Code's data terms in full are in our Claude Code for business guide.

Using Codex and Claude Code together, or switching later

OpenAI publishes an official plugin, codex-plugin-cc, to "use Codex from Claude Code to review code or delegate tasks". A developer working in Claude Code can hand a task or a code review to Codex without leaving it, and "usage will contribute to your Codex usage limits".

The plugin runs under whatever Codex account the developer is signed into on their computer, so the same rule applies: a company Codex seat or an API key, not a personal account. Every task it hands over goes to OpenAI as well as Anthropic, so both vendors' terms apply.

Switching from one tool to the other later doesn't touch the code. What moves is what your developers have written for the agent: the instruction files (AGENTS.md for Codex, CLAUDE.md for Claude Code) plus any custom commands and skills. In Composio's comparison, the everyday features of the two tools "line up almost one-to-one".

How to choose between Codex and Claude Code: a two-week trial

A trial helps you decide between Claude Code and Codex on your own code. Give both tools the same tasks from your real backlog for two weeks, run both at the same reasoning setting and record the sessions, and have your developers compare the results on four numbers:

1. Tasks solved without rework.
2. Hours of rework on the tasks that failed.
3. How often each developer hits the plan's limit.
4. The per-use bill, if you run the trial on API keys. On an OpenAI API key, Codex has no cloud tasks (it runs in the CLI, IDE extension or SDK), so test its cloud tasks on a Business seat.

A sheet like this per tool is enough:

A few dozen tasks can't detect a gap of a few points — if the two come out close, treat it as a tie and decide on cost and allowance.

Then decide by how you pay.

• Per use (API keys or Claude Enterprise usage). On Terminal-Bench 4.0 (6 November 2026, maximum effort), the runs' total bills over 330 attempts were $4,718.65 for Claude Code with Opus 5.5 and $634.24 for Codex with GPT-6.1 Sol, for 214 and 192 tasks solved. So each extra task Claude Code with Opus 5.5 solved cost about $186: ($4,718.65 − $634.24) ÷ (214 − 192). Set that against what a failed task costs you: the developer hours needed to finish or redo it by hand × their full hourly cost, salary plus overheads. If a failed task costs more than about $186, Claude Code with Opus 5.5 costs you less in total. If it costs less, Codex with GPT-6.1 Sol does, at about 7 fewer solved tasks in 100 and about 1/7 of the cost per solved task. On the board's own ranges the $186 could be anywhere from about $110 to about $550, so read it as an order of magnitude; your trial's numbers replace it.
• Team seats. Inside the allowance, the extra solved tasks cost nothing beyond the seat. The question is whose allowance runs out first in a working week (how often each developer hits the plan's limit). If neither runs out, take the pair that solves more. If one does, count the hours lost waiting, or the overage: Anthropic bills it at API rates, OpenAI in credits with no published dollar rate.

Whichever tool wins your trial, the result also depends on the process around it — who writes the task, who checks the output, who decides what gets released. Setting that up is what our vibe coding service does, around whichever tool your team buys from its vendor; we resell no tools or licences.

In our case. In our own repositories, 1,520 of our 1,717 commits (saved changes to code and content) in 2026 were written with an AI co-author (counted on 21 October). What made that work was the process around the agent: a task with acceptance criteria, a spec review before code, tests, a review, and a person who releases. However, we work in one tool and have not run a comparison of our own.

Sources

Read on 6 November 2026 unless marked:

• Terminal-Bench 4.0 leaderboard
• OpenAI, Codex pricing and GPT-6.1 Sol model page
• OpenAI, data controls FAQ and enterprise privacy
• OpenAI, Codex admin rollout guide and Codex CLI on GitHub
• OpenAI, codex-plugin-cc
• Anthropic, Claude pricing and Claude Code data usage
• Anthropic, Manage Claude Code costs (the $150–250 average; read 21 October 2026)
• Composio, Claude Code vs OpenAI Codex (published 18 August 2026)
• Firecrawl, Claude Code vs Codex (published 3 June 2026)