This translation is provided for convenience only. If there is any difference between this translation and the English version, the English version prevails.
1. Who we are
CalcHandbook (“CalcHandbook”, “we”, “us”) is operated by MARFEN-MAHMUT TARI, a sole proprietor based in Türkiye, trading under the name CalcHandbook. You can reach us at support@calchandbook.com.
By using calchandbook.com (the “Service”) you agree to these Terms. If you do not agree, please do not use the Service.
2. The Service
CalcHandbook provides browser-based engineering calculators — beams, frames, arches, plates, section properties, geotechnical and hydraulic checks — with diagrams, step-by-step derivations and printable reports. Some calculators are free; the full library requires a paid plan.
3. Engineering disclaimer
Results are for preliminary design, education and independent checking only. They are produced from classical closed-form and series solutions under the assumptions stated on each calculator. You are solely responsible for checking that a calculator fits your problem, for verifying every input and result, and for compliance with the codes and standards that apply to your project. Final designs must be reviewed and approved by a suitably qualified, licensed engineer.
The Service is not a substitute for professional engineering judgement, and we do not provide engineering services or advice.
4. Plans, billing and renewal
- Orders are processed by Paddle. Our order process is conducted by our online reseller Paddle.com. Paddle.com is the Merchant of Record for all our orders and handles payment, invoicing, sales tax / VAT and customer service enquiries related to payment and returns. Paddle’s Buyer Terms also apply to your purchase.
- Paid plans (Student, Professional, Team) are billed annually in advance in US dollars. Applicable taxes are calculated and added at checkout.
- Plans renew automatically at the end of each year unless you cancel before the renewal date. You can cancel at any time from the link in your Paddle receipt e-mail or by contacting us; access continues until the end of the paid period.
- We may change prices for future billing periods. We will notify you by e-mail at least 30 days before a price change takes effect at your next renewal.
5. Refunds
You can request a full refund within 14 days of your purchase or renewal. See our Refund Policy for details.
6. Licence and permitted use
- Free and Student plans are for personal, educational and non-commercial use. The Student plan requires a valid university e-mail address or other proof of enrolment.
- Professional and Team plans include a licence to use results and reports in commercial work.
- Team plans cover up to 5 named users. Accounts and seats are personal and must not be shared.
- You may not copy, scrape, resell, reverse-engineer or redistribute the calculators, their source code or content, or use automated means to access the Service in bulk.
7. Your content
Inputs, project names and report fields you enter belong to you. Unless a feature explicitly saves them to your account, they are stored only in your own browser. You grant us only the rights needed to operate the features you use.
8. Intellectual property
The Service, including its software, design, text, diagrams and derivations, is owned by us and protected by copyright and other laws. Formulas cited from published references (for example AWC Design Aid No. 6, Roark, Timoshenko, Das and Chow) remain attributed to their authors; references are given for verification only and do not imply endorsement.
9. Availability and changes
We aim to keep the Service available and accurate, but we do not guarantee uninterrupted or error-free operation. We may add, change or retire calculators. If we permanently remove a substantial part of a paid plan during your billing period, you may request a pro-rata refund for the remaining period.
10. Warranty disclaimer and limitation of liability
To the maximum extent permitted by law, the Service is provided “as is” and “as available”, without warranties of any kind, express or implied, including accuracy, fitness for a particular purpose and non-infringement.
To the maximum extent permitted by law, we are not liable for any indirect, incidental, special, consequential or punitive damages, or for loss of profits, data, business or goodwill, or for any damage arising from designs, construction or decisions based on results from the Service. Our total liability for any claim relating to the Service is limited to the amount you paid us in the 12 months before the claim. Nothing in these Terms limits liability that cannot be limited under applicable law, including your statutory rights as a consumer.
11. Termination
You may stop using the Service at any time. We may suspend or terminate access if you breach these Terms, for example by sharing accounts or redistributing content. Sections 3, 8, 10 and 12 survive termination.
12. Governing law
These Terms are governed by the laws of the Republic of Türkiye. Disputes will be handled by the competent courts of Türkiye, without prejudice to any mandatory consumer protection rights you have in your country of residence.
13. Changes to these Terms
We may update these Terms from time to time. The “Last updated” date above shows the current version. Material changes will be announced on the site or by e-mail before they take effect.
14. Contact
Questions about these Terms: support@calchandbook.com.