Terms of Use
A calculator, not a substitute for your judgment.
Last updated October 9, 2026
These terms cover your use of Practical Oilfield Calculator (the "app"). By using the app you agree to them. Apple's Standard License Agreement also applies.
Check every number
The app is a calculator. Check every number against your own math and your company's procedures before anything gets pumped.
Results depend on what you enter and on the pipe you pick. Pipe dimensions come from published API 5CT tables, and the pipe in your well may differ. You are responsible for the decisions you make on your job and for following your company's procedures, your supervisor's instructions, and the law.
Subscriptions
- Everyone gets three free calculations. After that, a subscription or a one-time lifetime purchase unlocks the calculators.
- Payment is charged to your Apple Account when you confirm the purchase.
- Monthly and yearly subscriptions renew automatically unless canceled at least 24 hours before the end of the current period. Your account is charged for renewal within 24 hours before the period ends.
- Manage or cancel in your iPhone's Settings, under your name, then Subscriptions. Refunds are handled by Apple.
- Prices are shown in the app before you buy.
No warranty
The app is provided "as is." We work to keep the math right and test it against worked examples, but we don't promise the app will be free of errors or always available.
Limits on responsibility
To the fullest extent the law allows, the people who made this app are not responsible for how its numbers get used on your job, or for any loss or damage that comes from using it. If the law doesn't allow that limit, our responsibility is limited to what you paid for the app in the twelve months before the claim.
Changes
If these terms change, the new version goes on this page with a new date. Using the app after a change means you accept it.