Calculator API Pricing

Every calculator on this site stays 100% free to use in the browser. These plans are only for the JSON API - subscribe for a higher monthly call quota and commercial use. The free tier needs no card.

Free

$0 / mo

Anonymous, IP rate-limited

✓ No sign-up, no key - call it straight away
✓ CORS-enabled, usable from the browser
✓ Add a free key for a small monthly quota
✓ Personal / non-commercial use

Read the API docs →

Developer

$9 / mo

10000 API calls per month

✓ Every calculator endpoint, same math as the site
✓ Commercial use, production-ready
✓ Cancel anytime, no lock-in
✓ The calculators on the site stay free for everyone

Get Developer →

Business

$49 / mo

100000 API calls per month

✓ Every calculator endpoint, same math as the site
✓ Commercial use in your own products
✓ Priority throughput + email support
✓ The calculators on the site stay free for everyone

Get Business →

Risk-free: 30-day money-back guarantee · Flexible: Change or cancel anytime · Fair: The calculators stay free either way

How the calculator API works

The API runs the exact same math as every page on this site. Anonymous calls are rate-limited by IP; a key raises that to your plan's monthly quota.

🔑 Create a free key on your account page

🔗 Send it as ?key=, Bearer or X-Api-Key

📈 Subscribe to raise your monthly quota

✅ Track usage on your account page

Full endpoint reference and code samples are in the API docs.