Terms of Service

Last updated: 17 August 2026

These terms are an agreement between you and the Institute of Spring Technology ("IST", "we") covering your use of Spring Calculator Professional at springcalculator.com ("the service"). By creating an account you accept them.

Your account

An account is for a single named user. Keep your sign-in details to yourself — colleagues who need access should have their own accounts. You're responsible for activity under your login and for keeping your account email current.

Free accounts and subscriptions

A free account lets you browse the built-in sample designs and view designs shared with you. Designing and saving your own springs requires a subscription, purchased per spring type or as an all-types bundle, billed monthly or annually through Stripe.

• Adding a spring type takes effect immediately; the pro-rata cost for the rest of the current billing period is charged to your card at the time.
• Removing a spring type takes effect at your next renewal. You keep access until then; no refund is made for the remainder of a paid period.
• Cancelling can be done at any time from your Account page and takes effect at the end of the period you've paid for.
• Price changes will be notified in advance and apply from your next renewal, never mid-period.

Your designs

Designs you create belong to you. You grant us the licence needed to store and process them in order to provide the service (including backups). Share links you create make a snapshot of that design viewable by anyone holding the link — creating and distributing them is your choice and your responsibility. You can export your work at any time (print, PDF and CAD export where available for the spring type).

Our software and data

The service, its calculation engine, materials database and documentation remain the property of IST. You may not copy, resell, reverse-engineer or provide the service to third parties as a bureau service.

Engineering responsibility

The service performs engineering calculations to recognised standards, based on the data you enter. It supports — but does not replace — professional engineering judgment. You are responsible for verifying that a design is fit for its intended application, including appropriate physical testing before production use, and for any use in safety-critical applications. IST accepts no responsibility for manufactured parts or for decisions made on the basis of calculated results.

Availability

We aim to keep the service available at all times but don't guarantee uninterrupted operation; brief maintenance windows and occasional faults are possible. Your data is backed up automatically as described in the Privacy Policy.

Liability

Nothing in these terms excludes liability that cannot lawfully be excluded. Subject to that, and to the engineering-responsibility section above, our total liability arising from the service in any 12-month period is limited to the subscription fees you paid in that period, and we are not liable for indirect or consequential losses such as lost profit or production.

Suspension and ending the agreement

We may suspend or close accounts that breach these terms, misuse the service, or have unpaid subscriptions. You may close your account at any time; see the Privacy Policy for what happens to your data.

General

We may update these terms from time to time; material changes will be notified and apply from your next renewal. These terms are governed by the law of England and Wales, and the courts of England and Wales have exclusive jurisdiction.

Questions? Contact us or email support@ist.org.uk.