These Terms govern your use of 1RM Calculator, including its app and website (the "Service"), operated by Yuri Koshiishi ("we," "us," or "our"). By using the Service, you agree to these Terms.
Last updated: September 26, 2026
The Service and Eligibility
The Service estimates your one-rep max and related training loads and lets you keep a history of your results on your device. Some features are free; others require a paid subscription or a one-time purchase. Available features and purchase conditions are described in the app.
If you are not legally able to enter into these Terms on your own, you must have the permission of your parent or legal guardian.
Estimates and Exercise Safety
The Service provides calculations and tracking tools, not medical advice, diagnosis, or treatment. One-rep max figures are estimates derived from the weights, repetitions, and effort ratings you enter. They may differ from what you can actually lift, especially at higher repetitions, and do not guarantee particular results.
Choose exercises, loads, and training intensity appropriate to your abilities and circumstances. Lifting heavy weights involves a risk of injury. Use proper technique and safety equipment, and seek advice from a qualified professional when needed, particularly if you have a medical condition or concerns about exercising safely. Stop exercising and seek appropriate help if you experience pain, dizziness, or other concerning symptoms.
Software License and Intellectual Property
You may use the Service for its intended purposes in accordance with these Terms. We and our licensors retain the rights in the Service's software, design, and branding, apart from content belonging to you.
For apps downloaded through Apple's App Store, Apple's standard End User License Agreement applies unless a custom license is supplied through the store. These Terms supplement the applicable software license. You may not copy, modify, distribute, resell, sublicense, reverse engineer, decompile, disassemble, or attempt to extract the source code of the Service except as expressly permitted by us, applicable law, or the relevant software license, including licenses for open-source components.
Acceptable Use
You must not use the Service, or help anyone else use it, to:
- violate the law or infringe another person's rights;
- bypass paid-feature restrictions or manipulate purchase or subscription information;
- disrupt, damage, or overload the Service or our providers' systems;
- probe or test the security of the Service without our authorization, except where permitted by applicable law.
Report suspected security vulnerabilities privately to [email protected].
Your Records
You retain your rights in the records you enter. They are stored on your device, and you are responsible for keeping copies you want to preserve, for example by using the app's CSV export. Uninstalling the app or using Reset Data removes records from the device, and we cannot restore them.
Personal information is handled as described in our Privacy Policy.
Purchases, Subscriptions, and Refunds
Before you confirm a purchase, the purchase screen and store checkout show the price, applicable taxes, billing interval or one-time nature of the purchase, and included benefits. Payment is handled by the App Store or Google Play account used for the purchase. Paid access becomes available after the purchase is confirmed. If it does not activate, use Restore on the purchase screen or contact us.
Subscriptions renew automatically for the displayed billing period until canceled. A lifetime purchase is a one-time payment that does not renew and provides the paid features included in the app for as long as we offer and maintain the Service.
- App Store: Manage or cancel in your device's Settings → your name → Subscriptions → 1RM Calculator. Cancel at least 24 hours before the current period ends to avoid renewal. See Apple's cancellation instructions.
- Google Play: Manage or cancel in Google Play → profile → Payments & subscriptions → Subscriptions → 1RM Calculator. Cancel before the next renewal to avoid the next charge. See Google Play's cancellation instructions.
Cancellation normally stops future renewals while paid access continues until the end of the paid period, subject to the store's rules. Deleting the app does not cancel a subscription or automatically create a refund.
For App Store refunds, use Apple's refund request service. For Google Play purchases, follow Google Play's refund process or contact us with the order details. Eligibility depends on the purchase, store rules, and applicable law; cancellation alone does not guarantee a refund for the current period. Nothing in these Terms excludes mandatory refund or consumer rights.
Third-Party Services
App stores and other third-party services have their own terms. We are responsible for our Service; those providers are responsible for their own services.
Availability and Changes
The Service requires a compatible device and operating system. Purchases and restoring purchases require an internet connection. You are responsible for your internet and mobile-network charges.
We may change or discontinue features. For changes materially affecting existing paid access, we will provide notice and any remedies required by the purchase terms or applicable law.
Disclaimers and Liability
We use reasonable care in providing the Service but cannot promise uninterrupted or error-free operation, complete accuracy of estimates, or particular fitness outcomes. Except for our express commitments and warranties required by law, the Service is provided as available.
To the extent permitted by applicable law, we are not responsible for indirect or consequential losses arising from use of the Service. Nothing in these Terms excludes or limits liability that cannot lawfully be excluded or limited, including mandatory consumer protections and liability for intentional misconduct or gross negligence.
Governing Law and Disputes
These Terms are governed by the laws of Japan. Contact us first so we can try to resolve any concern. Subject to mandatory law, the Tokyo District Court has jurisdiction over disputes concerning the Service. If you are a consumer, this does not remove protections under mandatory laws where you live or any right to bring proceedings in your local courts.
Changes to These Terms
We will publish updates with a revised date and notify you of material changes through an appropriate channel. Where advance notice or consent is required, we will provide it or obtain it before the change takes effect. If a provision is unenforceable, the remaining provisions continue to apply to the extent permitted by law.
Contact
Email [email protected].