Terms of Service

By accessing or using MechanixCalc ("the Service", available at mechanixcalc.com), you agree to be bound by these Terms of Service ("Terms"). If you do not agree, do not use the Service.

The Service is operated by Mechanixer Dooel Skopje, a company registered in North Macedonia ("we", "us", "our").

MechanixCalc is a web-based engineering calculation platform providing professional tools for mechanical engineers. The Service is offered across the following subscription tiers:

• Free— Unit converter, reference library, comparison mode, steel sections, GD&T calculator, and tolerance stack-up. No account required. Always free.
• Core— $19/month, or $15/month billed annually ($180/year). Everything in Free plus all 48 engineering calculators (rotating machinery, power transmission, machine elements, structural, manufacturing, fluid & thermal, and lifting), the AI assistant, saved calculations, branded PDF reports, and public share links.
• Pro— $39/month, or $29/month billed annually ($348/year). Everything in Core plus the three Design Studio schematic editors (P&ID, Fluid Power, and Electrical), custom logo / white-label PDF reports, cross-tool workflow linking, priority support, and early access to new tools.
• Expert — $69/month, or $49/month billed annually ($588/year). Everything in Pro plus public REST API access via self-serve API keys, CAD add-ins (Fusion 360, in development), a higher AI assistant limit, design history and versioning (in development), and dedicated priority support.
• Team — from $49/seat/month billed annually. Full Expert-level access for every seat at volume pricing. Seat management and shared workspace features are currently in development; contact us to arrange multiple team accounts manually in the meantime.
• Enterprise — Custom pricing for 20+ seats and optional on-premise deployment. Contact us at hello@mechanixcalc.com for details.

Anonymous preview. Unauthenticated ("anonymous") visitors may access the tools for a one-time 30-minute free preview. After the preview expires a hard gate is shown and the visitor must create a free account (or sign in) to continue. The preview cannot be dismissed. One preview per device/browser is permitted.

14-day free trial. When you create a free account you receive a 14-day trial with full Expert access to all tools and the schematic editors. No credit card or payment method is required to start the trial, and the trial does not auto-renew or charge you when it ends.At the end of the 14 days your account simply reverts to the Free tier (unit converter, reference library, comparison mode, steel sections, GD&T calculator and tolerance stack-up), and you may upgrade to a paid plan at any time. One trial per account.

To enforce these limits and prevent abuse, we collect a browser fingerprint, IP address, and set a server-side cookie, and we rely on verified-email account registration. See our Privacy Policy for full details on the data collected and the legal basis (GDPR Art. 6(1)(f) — Legitimate Interest).

You must create an account to access tools beyond the Free tier. You are responsible for maintaining the confidentiality of your login credentials and for all activity under your account. You agree to provide accurate registration information and to notify us immediately of any unauthorized use at hello@mechanixcalc.com.

Paid subscriptions are available on monthly or annual billing cycles. Current pricing:

All payments are processed by Paddle.com, our authorized reseller and Merchant of Record. Paddle handles all billing, invoicing, and tax compliance on our behalf. By purchasing a subscription you also agree to Paddle's Terms of Service.

Subscription fees are charged at the start of each billing period and are non-refundable except as described in our Refund Policy. Prices may change with 30 days' notice.

The following tools are always available without an account or payment: Unit Converter, Reference Library, Comparison Mode, Steel Sections, GD&T Calculator, and Tolerance Stack-up. Free tools are provided "as is" and may be changed or discontinued at any time.

You agree not to:

• Use the Service for any unlawful purpose
• Attempt to reverse-engineer, scrape, or copy the calculation algorithms
• Share account credentials or resell access to the Service
• Circumvent or attempt to circumvent trial or subscription limits
• Interfere with or disrupt the Service or its infrastructure
• Use automated tools to access the Service in a way that exceeds normal use

API access & API keys (Expert plan).The public REST API is available on the Expert plan via personal API keys (the same keys used by our CAD add-ins). Your API key is a secret credential tied to your account: you are responsible for keeping it confidential and for all activity performed with it, just as for your login. Do not share, publish, or embed your key where others can extract it, and do not use the API to circumvent plan limits, share or resell access, or place automated load beyond reasonable use. We may rate-limit, revoke a key, or suspend access for misuse. Results obtained through the API or a CAD add-in are subject to the same Engineering Disclaimer and verification responsibility as results in the web app (Section 9).

All content, algorithms, design, and code within the Service are owned by MechanixCalc and protected by applicable intellectual property laws. You may use the results of calculations for your own professional work. You may not reproduce or redistribute the Service itself.

MechanixCalc provides engineering calculations as a decision-support aid for qualified engineers, for reference and preliminary work only. It is not a certified, stamped, or signed engineering design, and no output constitutes professional engineering advice or certification.

Two classes of result. (a) Standard-validated calculations implement a cited governing standard or recognised textbook method and are checked against that standard by an automated test suite. (b) Engineering estimates — clearly marked in-app with an “Engineering estimate — not standard-validated” badge — are simplified, heuristic, or manufacturer-specific models for which no public governing standard exists; they are for preliminary sizing only. Certain tools (including, without limitation, slewing-ring bearings, shaft couplings, and worm gears) are estimate-based and must be verified against the component manufacturer's selection data.

Your responsibility. You are responsible for the suitability of any result for your application, including selecting the correct standard, inputs, units, and assumptions. Every result — validated or estimate — must be independently reviewed and verified by a competent, licensed/chartered Professional Engineer before it is relied upon for manufacture, construction, procurement, certification, or any decision affecting safety, property, or life. The Service does not relieve you or your engineer of that duty.

No warranty.The Service is provided “as is” and “as available” without warranties of any kind, express or implied, including any implied warranty of accuracy, completeness, merchantability, or fitness for a particular purpose. We do not warrant that any calculation is free from error or suitable for any specific design. See the full Engineering Disclaimer.

The Service, including all calculations, results, estimates, verdicts, reports, data, charts, and AI responses, is provided “as is” and “as available” without warranty of any kind. To the maximum extent permitted by applicable law, we and our operator Mechanixer Dooel Skopje expressly disclaim all warranties and conditions, whether express, implied, statutory, or otherwise, including without limitation the implied warranties or conditions of merchantability, satisfactory quality, fitness for a particular purpose, accuracy, reliability, title, and non-infringement, and any warranties arising from course of dealing or usage of trade. We do not warrant that the Service will be uninterrupted, secure, or error-free, or that any result, estimate, or report is accurate, complete, current, or suitable for any purpose. No advice or information obtained from the Service creates any warranty not expressly stated in these Terms.

To the maximum extent permitted by applicable law, in no event will MechanixCalc, Mechanixer Dooel Skopje, or their owners, directors, officers, employees, agents, licensors, or suppliers be liable for any indirect, incidental, special, consequential, exemplary, or punitive damages, or for any loss of or damage to profits, revenue, business, goodwill, data, or anticipated savings, or for any property damage, personal injury, or death, arising out of or relating to your use of, inability to use, or reliance on the Service or any result, estimate, verdict, report, or AI response, whether based on warranty, contract, tort (including negligence), strict liability, statute, or any other legal theory, and whether or not we were advised of the possibility of such damages.

Liability cap.To the maximum extent permitted by applicable law, our and our operator's total aggregate liability for all claims arising out of or relating to the Service or these Terms will not exceed the greater of (i) the total fees you actually paid to us in the twelve (12) months immediately preceding the event giving rise to the claim, or (ii) one hundred euros (€100). These limitations are a fundamental basis of the bargain between you and us and apply even if any limited remedy fails of its essential purpose.

Mandatory exceptions. Nothing in these Terms excludes or limits any liability that cannot be excluded or limited under applicable law, including liability for death or personal injury caused by negligence, for fraud or fraudulent misrepresentation, or for any other liability that cannot lawfully be limited. If you are a consumer, you may have statutory rights that these Terms do not affect. Where any exclusion or limitation in this section is held unenforceable in any jurisdiction, it applies to the maximum extent permitted by the law of that jurisdiction, and our liability is limited to the smallest amount permitted by law.

You acknowledge that engineering analysis and design carry inherent risk and that you assume all risk arising from your use of, and reliance on, the Service. To the maximum extent permitted by law, you agree to defend, indemnify, and hold harmless MechanixCalc, Mechanixer Dooel Skopje, and their owners, directors, officers, employees, and agents from and against any and all claims, demands, liabilities, damages, losses, costs, and expenses (including reasonable legal fees) arising out of or in any way connected with: (a) your use of the Service or any result, estimate, verdict, or report; (b) any design, calculation, product, structure, component, or decision you create, make, certify, or rely upon using the Service; (c) your breach of these Terms; or (d) your violation of any law or any right of a third party. This indemnity does not apply to the extent a claim arises from our own fraud or from a liability that cannot be limited under applicable law.

You may cancel your subscription at any time from your account settings. We may terminate or suspend your account immediately for violations of these Terms, including attempted circumvention of trial or subscription limits. Upon termination, your right to use the Service ceases. Provisions that by their nature should survive termination — including Sections 8–12, 15, and 16 — will do so.

We may update these Terms at any time. We will notify registered users by email of material changes at least 14 days in advance. Continued use after the effective date constitutes acceptance of the updated Terms.

These Terms, and any dispute or claim arising out of or relating to them or the Service (including non-contractual disputes), are governed by the laws of the Republic of North Macedonia, where our operator is established, without regard to its conflict-of-law rules and excluding the United Nations Convention on Contracts for the International Sale of Goods.

Forum (business users). Where you use the Service for professional, business, or commercial purposes, you and we submit to the exclusive jurisdiction of the competent courts of Skopje, North Macedonia, for any dispute, and you waive any objection to that forum on the grounds of venue or inconvenient forum.

No class actions. To the maximum extent permitted by law, any dispute will be brought only in your or our individual capacity, and not as a plaintiff or class member in any purported class, collective, consolidated, or representative proceeding.

Consumers. If you use the Service as a consumer, nothing in this Section deprives you of the protection of the mandatory consumer-protection provisions of the law of your country of habitual residence, and you may be entitled to bring or defend proceedings in the courts of that country. Mandatory local law prevails over any conflicting provision of these Terms.

• Severability. If any provision of these Terms is held invalid, illegal, or unenforceable, it will be modified to the minimum extent necessary to make it enforceable (or, if it cannot be, severed), and the remaining provisions remain in full force.
• Entire agreement. These Terms, the Privacy Policy, the Refund Policy, and the Engineering Disclaimer are the entire agreement between you and us regarding the Service and supersede all prior understandings.
• No waiver. Our failure to enforce any provision is not a waiver of our right to do so later.
• Assignment. You may not assign these Terms without our consent; we may assign them in connection with a merger, acquisition, or sale of assets.
• Force majeure. We are not liable for any failure or delay caused by events beyond our reasonable control.
• Survival. Sections concerning intellectual property, disclaimers, limitation of liability, indemnification, governing law, and these general provisions survive termination.

Questions about these Terms: hello@mechanixcalc.com

Paid plans (Core and above) include an AI Engineering Assistant powered by Anthropic's Claude API. By using this feature you acknowledge the following:

• Data transmission to Anthropic. When you send a message, the text of your message and a plain-text summary of your current calculation inputs and results are transmitted to Anthropic, Inc. for processing. No source code, proprietary formulas, or personally identifiable information beyond what you type is included. Anthropic processes this data in accordance with their Privacy Policy.
• No persistent storage of chat messages. Chat conversations exist only in your browser session. MechanixCalc does not store your AI chat messages on its servers. Messages are discarded when you close or refresh the tool.
• Rate limits. AI queries are subject to per-tier hourly limits: Core — 10 questions/hour; Pro — 20 questions/hour; Expert — 50 questions/hour. Limits reset every 60 minutes.
• Advisory use only. AI responses are for guidance and interpretation of your results. They are not a substitute for qualified engineering judgment. All AI suggestions must be independently verified by a competent engineer before use in any real-world design or application.
• IP protection. The assistant is programmed never to disclose calculation methodologies, formulas, or proprietary algorithms. Attempts to extract such information via the chat interface will be refused.
• Acceptable use. You agree not to use the AI Assistant to attempt jailbreaks, extract proprietary information, generate harmful content, or circumvent the rate limits through automated means.