Last updated: 27 October 2026
This policy explains how Ferment Calculator at fermentcalculator.com handles information when you browse the site, use its tools or submit a form.
Information you provide
Contact messages. The contact form asks for your name, email address, subject and message. Submissions are sent through Web3Forms for delivery and may also be recorded in the site’s Supabase database. This information is used to respond, investigate reported issues and maintain correspondence records. Do not include passwords, payment details or other sensitive information in your message.
PDF requests and optional marketing. Download forms record your first name (where requested), email address, the page you are on and the site in the existing Supabase subscriber table. The optional marketing checkbox starts unticked. You can get your PDF without subscribing. We record the checkbox choice in the same request; if you opt in, we also record the consent timestamp and the version of the consent wording. When unticked, the choice is false and those two consent fields are empty. Submitting a download request alone does not give marketing permission. For saved PDF guides, Cloudflare checks a Turnstile verification token before we save the request. The file is read from private Cloudflare R2 storage and delivered by your chosen method: saved in your browser or sent as an attachment through Cloudflare Email Sending. Your email address and the requested file are processed for that delivery, whether or not you choose marketing. If email delivery fails, you can choose to save your authorised PDF instead. For personalised calculator batch-card emails, Cloudflare also renders your submitted calculator settings, results and instructions into the PDF attachment. These generated cards are not stored at a public download URL. Turnstile may process browser and network information to check for automated requests.
Newsletter signup. The newsletter form asks for your first name and email address and records them, with the page you signed up on, in the same Supabase subscriber table. Signing up records marketing permission, with its timestamp and consent wording version, and nothing is downloaded. The same unsubscribe and withdrawal rules below apply.
Marketing permission covers Ferment Calculator updates, new calculators and fermentation guides. You can withdraw permission at any time by using an unsubscribe link in a marketing email or by contacting us through Contact. Recording a choice does not itself send emails. Any future mailing integration must respect the choice for this site and later withdrawals. Repeated requests can create separate records; a later opt-in record must not override a subsequent withdrawal without a new consent.
Calculator inputs
Calculator arithmetic runs in your browser. You do not need to create an account to see results. Submitting a separate email or download form sends the information requested by that form. Analytics and usability services may also record site interactions, so calculator use should not be treated as a confidential channel for sensitive information.
Analytics, cookies and advertising
The site is configured to use Google Analytics and Microsoft Clarity to understand page visits, device/browser information and how visitors interact with pages. These services may use cookies or similar technologies. Clarity can provide interaction recordings and heatmaps. Processing depends on the service configuration, browser settings and any available privacy choices.
See Google’s privacy policy, Google’s cookie information and Microsoft’s privacy statement for details about their services.
The production site may display Google-served advertising. Advertising providers can process device, browser and interaction information and use cookies or similar technologies to deliver and measure ads. Information about Google’s advertising data use is available at Google’s partner-site privacy page.
You can manage cookies in your browser and use the privacy choices offered by the relevant providers. Blocking analytics or advertising cookies does not change the arithmetic performed by the calculators.
Product links and purchases
Equipment recommendations may contain affiliate links. Retailers can use their own tracking technologies after you follow a link. Our own books, logs, apparel and accessories are sold through Etsy. Etsy and its payment providers handle checkout, payment and order information under their own policies. Payment card details are not collected through a Ferment Calculator checkout.
As the seller, the shop may receive order and contact information from Etsy to fulfill purchases and handle customer support.
See the affiliate disclosure and Etsy’s privacy policy.
Sourdough feeding calculator: peak times
The sourdough feeding calculator remembers your last feed in your own browser’s local storage: the ratio, amounts and time you used it. On your next visit it asks once when that feed peaked. If you tap a time, it keeps that answer in your browser too, so it can show when your own starter usually peaks. “Didn’t check” records nothing. Clearing your browser data removes all of this, and it is not copied to other browsers or devices.
When you tap a peak time, an anonymous copy is also stored in a separate Supabase table. Each copy holds the feed amounts and ratio, the hours you tapped, a two-letter country code taken from your browser’s language setting, and the date. It does not include your name, email address, IP address or any account or device identifier, and it is not linked to the newsletter or download records, so it does not identify you. We use these copies to check and improve the calculator’s timing ranges and to publish summary figures, such as a typical peak time for a feeding ratio. Summary figures are shown only once enough answers exist that no single one can be picked out. Copies are kept for up to three years. Because a copy carries nothing that identifies you, we cannot find or delete a single one afterwards.
Sourdough starter manager: your feeds and peaks
The sourdough starter manager keeps your feed journal in your own browser’s local storage: each feed’s ratio, starter temperature, time, notes, and the peak and rise you record. Clearing your browser data removes it, and it is not copied to other browsers or devices.
When you save a peak, an anonymous copy is also stored in a separate Supabase table. Each copy holds the feeding ratio, the starter temperature, the hour of the day you fed (not the date or minute), the hours to peak, the rise if you gave one, whether you recorded it as it happened or afterwards, the peak window the page showed you, how many peaks you had already recorded at that ratio, a two-letter country code taken from your browser’s language setting, and the date the copy was stored. It also holds a random starter code made in your browser, so that repeat feeds of the same starter can be studied together. That code is not taken from your device and is not linked to your name, email address, IP address, notes, or the newsletter or download records, so it does not identify you. We use these copies to improve the starter timing estimates and to publish summary figures, shown only once enough peaks exist that no single one can be picked out. Copies are kept for up to three years. Because a copy carries nothing that identifies you, we cannot find or delete a single one afterwards.
When you email yourself your starter log, you can also tick “Check in with me about my starter in a week. This adds you to our marketing list.” This is optional. If you tick it, you join our marketing email list (the same consent as “Email me Ferment Calculator updates”), and we store your first name, email address and the feed journal shown in your log (ratios, temperatures, feed and peak times, rises and your notes) in Supabase, and send you one check-in email about a week later that uses those numbers. Replies come to us, and we use them to answer you and to improve the starter guidance. Unsubscribing stops the check-in. You can ask us to delete your saved log at any time through the contact page. Saved logs are kept for up to three years.
Service providers and storage
Hosting, analytics, form delivery and database providers process information as needed to provide their services. Information may be processed outside your country. We do not sell or rent the contact details submitted through our forms. Sharing with service providers for hosting, delivery or storage is separate from selling those details.
We keep submitted information for as long as needed for its stated purpose, including handling correspondence, managing subscriptions and meeting applicable recordkeeping obligations. Provider retention settings and backup practices can affect when copies are removed.
Your choices and requests
Depending on your location, you may have rights to request access, correction, deletion or restriction of personal information, or to object to particular processing. Contact us to make a request. We may need enough information to verify and locate the relevant record. Rights and exceptions depend on applicable law.
The site is not directed at children under 13. If you believe a child has submitted personal information, contact us so the record can be investigated and removed where appropriate.
Updates and contact
Changes to this policy will be reflected in the date above. For privacy questions or requests, use the contact page.