Several blog posts already answer "is my AI coding plan worth it?" by hand, from one account's own token counts — one reports ten billion tokens across eight months of Claude Code usage that would have cost $15,000 on the API against an $800 subscription bill, with cache reads above 90% of the total. That arithmetic is real and worth reading. It is also not your arithmetic.
A blog post or forum thread working the numbers by hand reports one account's result: a specific seat count, a specific usage tier, a specific cache-read share, computed once and published. Reading a few of these gives a useful sense of the shape of the answer — subscriptions tend to win big for heavy, cache-heavy usage — but no two accounts split their tokens the same way, and none of these posts let you swap in your own numbers.
This calculator runs the identical subscription-vs-API arithmetic — fresh input, output, cache write, and cache read priced separately, because cache reads are typically billed at a fraction of the fresh-input rate and dominate real agentic-coding usage — from the usage and rates you enter, and reports the break-even point where the two would swap places.
| Question | Where to answer it |
|---|---|
| What does this generally look like for a heavy coding-agent user? | The published write-ups — a useful sanity check before you dig into your own numbers. |
| Is my plan cheaper than the API, given my own usage? | This calculator — your numbers, not a published account's. |
| How much would my usage need to change to flip the answer? | This calculator's break-even figure, computed rather than a second round of hand arithmetic. |
| Is anything I enter uploaded anywhere? | No. The calculator runs entirely in your browser; nothing is sent to a server. |
Not affiliated with, endorsed by, or sponsored by Anthropic, Cursor, GitHub, Microsoft, or OpenAI. Each is a trademark of its respective owner, named here only to describe the plans this calculator compares.
Those posts are real and useful as a sanity check — several report figures like ten billion tokens across eight months of Claude Code usage costing $15,000 on the API against an $800 subscription bill, with cache reads above 90% of the total. But every one of those numbers comes from one specific account's usage. Your seat count, your usage tier, and your cache-read share are almost certainly different, and none of those posts let you substitute your own numbers — they report what happened to someone else.
Only roughly, and it is easy to get wrong in a way that favors the wrong answer. The ratio between subscription and API cost is not linear in total tokens — it depends on how your usage splits across fresh input, output, cache write, and cache read, and cache reads are typically billed at a small fraction of the fresh-input rate. Scaling someone else's total by your rough usage multiple ignores that split entirely, which is exactly the shortcut this calculator exists to skip.
Opening your plan's pricing page for the monthly price, opening the vendor's separate API pricing page for four different per-token rates, estimating your own fresh input, output, cache write, and cache read tokens, and multiplying each rate by its token count before summing and comparing to the subscription price — then redoing all of it if you want to know how much your usage would need to change to flip the answer. It is arithmetic anyone can do; it is also easy to drop a rate, use last month's price, or skip the break-even step because it takes another round of multiplication by hand.
Not automatically — it runs the same arithmetic you could run yourself, with the same dated default rates you should still verify against the vendor's current pricing page. What it changes is friction: the four-rate, cache-split arithmetic is filled in for you and the break-even usage level is computed rather than left as a second calculation, so there is one less place to drop a term or forget a step.
Want the reasoning behind the cache-read split first? Read how AI coding plan pricing actually works.