Free Tool
API Cost Calculator
How much will your API usage actually cost? Enter your pricing model and volume and get your monthly & annual spend instantly — including graduated tiers and a 12-month growth projection.
Breakdown
12-month projection
We only store your estimate if you email it to yourself. No spam.
Project the bill before it arrives
API pricing is designed to look inexpensive at the volumes you test with, and to scale in ways you do not notice until the invoice.
Put your expected call volume in and get the monthly cost — including what happens past the included allowance, which is where the surprise usually lives.
The mistake that costs the most
Estimating from a working prototype. A prototype makes clean, successful calls in a controlled sequence. Production makes retries, duplicate calls from race conditions, polling loops firing more often than intended, and calls from test environments nobody remembered to separate.
- A reasonable rule: take your prototype volume and add 30 to 50%.
- Then check the overage rate on the plan you are considering — that number, not the headline price, is what you pay when you guess low.
- The gap is rarely the per-call price. It is almost always the call count.
What actually drives the cost
Four things, and only one of them is the price you compared vendors on.
- Call volume, which is the one people estimate badly.
- The included allowance and what happens the moment you pass it.
- Per-unit price beyond that, plus any fixed platform fee that applies regardless of usage.
Build cost against running cost
Two separate budgets, and teams usually estimate one well and the other badly. The build is paid once — connecting, testing, handling errors. The run is paid every month for as long as the integration exists.
- Quotes covering only the build are why integration budgets get uncomfortable in month six.
- Over three years a $449 monthly run costs twice the $8,000 build.
- Ask for both numbers before you sign anything.
Your figures stay in your browser
Volumes and pricing are commercially sensitive, and they are not sent anywhere here.
- The calculation runs in the page you are looking at.
- Which means real contract rates can go in rather than rounded stand-ins.
- No account, and nothing kept afterwards.
Four numbers worth keeping
Why Parix.ai gives this away
We build integrations, which means we have had the month-six conversation about a running cost nobody quoted. These tools are the same checks we run before quoting — which is why there is no paywall and no sign-up.
Estimate my billWho uses it
Developers sizing a third-party dependency before committing, product managers comparing vendors on total cost rather than headline price, and finance teams forecasting a line item that keeps moving.
If the API is an LLM
Token pricing works differently — output costs several times input. The LLM Token Cost Calculator handles that case, and the AI Integration Cost Estimator covers the build side.
Checked against a real build
Our AI integration team will sanity-check an estimate against what the integration actually costs once it is running.