Subscription vs API Cost Calculator

A flat plan and metered API access aren't really competing on the same axis — one is a fixed monthly cost regardless of how much you use it, the other scales exactly with usage — but most people asking "should I stay on my plan or switch to the API" are really asking a single practical question: at my actual usage, which one is cheaper. This tool answers that directly, from numbers you supply.

Why you enter the plan price yourself

The calculator starts empty and shows no verdict until a price is in place, because the price that matters is the one you actually pay — and that depends on your region, currency, tax and billing period. OpenAI's US list prices sit just under the field as one-tap starting points, dated and sourced on the plans page; tap one to begin, then overwrite it with your own figure if it differs. (Until October the field quietly started at a familiar US plan price, as if it were everyone's; that default is gone, and the list prices only ever fill in when you choose them.) The answer then stays correct for your region and plan. If you're on a ChatGPT plan, Codex usage beyond your included allowance is metered in credits rather than API tokens — the Codex credits calculator prices a task that way, and Codex plans and usage limits shows what each plan includes.

What "your usage pattern" means here

You describe a workload the same way the token-cost estimator does — input and output token counts, a model and service tier, and how often you actually run it — and the calculator prices the metered side against the exact published rates for that combination, including the long-context repricing rule if your workload crosses it. That total, multiplied out to a monthly figure, sits next to the flat plan price you entered. Whichever is lower for your specific numbers is your answer; the calculator doesn't have an opinion beyond that.

The case metered pricing quietly wins

A flat plan is a bet that you'll use enough of it to make the fixed price worth paying. Below a certain usage level, that bet doesn't pay off, and it's easy to keep paying for a plan out of habit long after your actual usage has dropped — a slow month, a project that wound down, a workflow that moved to a different tool for part of what it used to do through this one. Because the metered side of this comparison scales down to genuinely small numbers, it's a useful check to run periodically even if you're confident the plan is still the right call, specifically because that confidence is the thing most likely to go stale unnoticed.

The case a flat plan quietly wins

Heavy, consistent usage is where a flat plan's fixed cost stops being a bet and starts being a straightforward discount against what the same volume would cost metered — and unlike the API, a subscription plan doesn't expose you to the long-context repricing cliff or a rate-limit ceiling on any individual request, because you aren't paying per token or per call at all. If your usage is high enough and steady enough that the metered total would land well above the plan price, the calculator will show that clearly, and there's no further nuance to chase — the flat price wins on the numbers alone.

Where rate limits complicate the comparison

A cost comparison alone can understate the real cost of a wrong choice on the API side: metered access is also gated by the usage tier your account has reached, and a workload sized for a plan-equivalent volume can run straight into a throughput ceiling well before it runs into a spend ceiling, especially on the models with the tightest published limits. If your calculated metered total looks attractive, it's worth checking the rate-limit tier planner against the same workload before committing — a cheaper total that you can't actually push through the API at the rate you need it isn't really cheaper.

What this tool doesn't try to do

It prices a single, steady usage pattern against a single flat plan price — it doesn't model a usage pattern that varies sharply month to month, and it doesn't account for anything a plan bundles beyond raw model access, since this site has no way to verify what's included in a plan you didn't tell it about. Treat a result here as a fair comparison for the specific numbers you entered, and re-run it whenever either side of the comparison — your actual usage, or the plan price you're paying — meaningfully changes.