Your numbers stayon your side of the glass.
No account. No scenario database. The calculator is designed to work in your browser without sending your financial inputs to us.
Effective · 24 July 2026
Privacy in plain language
Calculation
The scenario is calculated on your device. There is no API request or database write required to produce the result.
Saving
A working draft and any named scenarios are saved in local browser storage so they remain on this browser and device.
Sharing
If you create a share link, the scenario is encoded in its browser-only URL fragment. Anyone with the complete URL can read the values it contains.
Analytics
Anonymous product and performance events use redacted page paths. Calculator values, results and shared-scenario contents are never included.
LOCAL / 01
What your browser keeps
The calculator keeps one working draft and any named scenarios you deliberately save using your browser’s local storage. Named scenarios are separate snapshots: editing the draft does not silently update them until you choose Save. Both stay tied to this site, browser profile and device. They do not automatically follow you to another device and are not synced through a Rent vs Buy UK account, because there are no user accounts.
- May be stored
- Property, rent, deposit, rate, cost, horizon and scenario assumptions entered in the calculator. If you use UK HPI evidence, the selected area, property type, historical window, source release and observation dates are stored too. ONS rent evidence stores the selected local authority or rental market area, segment, benchmark, observation basis, historical window, source release and dates. Investment evidence stores the public dataset and fund IDs, historical window, derived GBP and CPIH figures, nominal rate basis, and source dates. Property evidence likewise stores its nominal basis and CPIH context. The nominal/today’s-money display choice and future inflation assumption are also kept. A named scenario also stores the title you choose and local created/updated timestamps.
- Not imported
- Bank transactions, household finance records, raw exports, private presets or personal scenarios from any other app.
How to remove it
Delete an individual scenario from the Load list, or clear this site’s stored data in your browser settings to remove the working draft and every saved scenario. Clearing site data, using a private browsing window, or switching browser profiles will also prevent or remove access. Browser storage is convenient, not encrypted vault storage: on a shared computer, another person using the same profile may see it.
PUBLIC / 02
A share link is public by design
Explicit values in a shared URL take priority over any draft or named scenario saved in the recipient’s browser. That makes the link reproducible—but also means the complete URL itself carries the scenario. New links put those values after #scenario=. Browsers do not send that fragment in the HTTP request to the host. The local title of a named scenario is never included in the link.
An evidence-backed share link also includes the selected public geography, property type, history and UK HPI release so the origin of the property-growth rate remains visible. Rent evidence likewise includes the public geography, rental segment, benchmark, achieved- or advertised-rent basis, historical window and ONS PIPR release. A referenced investment assumption includes its public dataset ID, representative fund, historical window, FX endpoints, CPIH snapshot and nominal basis; the display basis and future inflation assumption are included too. It does not include a full address, but an area can still be identifying when combined with other information.
Before you share
Treat the whole URL like a public document. Review the values and avoid adding names, addresses or notes that identify a person or property.
Complete URLs may appear in browser history, messaging apps, screenshots, browser extensions and any service or person you give them to, and can be forwarded by a recipient. This site also sends a no-referrer policy. Older query-string share links are still accepted: their values reach the hosting infrastructure on the first request, then the browser immediately rewrites them into the fragment format. Removing the local draft or saved scenario does not revoke a link already shared. Use rounded values if exact numbers are sensitive.
ANALYTICS / 03
Aggregate usage analytics
We use Vercel Web Analytics and Speed Insights to understand, in aggregate, how the production calculator is used and performs so that we can improve its usability, reliability and explanations. Preview, local and self-hosted builds do not load these services. This is product telemetry, not a user-level activity history.
What may be counted
A redacted page path, timestamp, referrer, approximate location, browser, operating system, device category, network speed and Core Web Vitals. We also count a small vocabulary of interactions: starting the calculator, opening refinements or evidence choosers, applying evidence, reaching the full analysis, changing the display basis, saving locally, copying a share link and encountering a controlled field-validation reason.
What is never sent
Property prices, rent, deposits, mortgage or growth assumptions, exact locations, model results, wealth differences, scenario names, copied values, shared URLs, query strings, URL fragments, free text or a persistent household or visitor identifier.
URL redaction and identification limits
Before every analytics or performance event is sent, the app removes the entire query string and URL fragment. If the preference cannot be read or a URL cannot be safely parsed, the event is discarded. Custom events accept only fixed event, field, section and reason labels; they cannot include an entered value.
Vercel states that Web Analytics does not use cookies, reports aggregated data and uses a request-derived visitor hash that is discarded after 24 hours. Vercel states that Speed Insights measurements are anonymous and cannot reconstruct a browsing session or identify a visitor. We do not use session replay, advertising pixels, cross-site tracking, profiling, analytics drains or a separate raw-event store. Read Vercel’s Web Analytics privacy information and Speed Insights privacy information .
Purpose, legal basis and your objection
Where this processing involves personal information, our UK GDPR lawful basis is the legitimate interest in understanding and improving the service. Our assessment is that aggregate counts and performance measurements are a proportionate way to find friction, while URL redaction, fixed event labels, the absence of financial values and persistent IDs, and this free device-level opt-out limit the effect on visitors.
For storage or access technologies used solely for these statistics, we rely on the statistical-purposes exception under the Privacy and Electronic Communications Regulations. The ICO’s current exception guidance requires clear information and a simple, free way to object. You can object on this device below. This approach must be reviewed before adding advertising, session replay, persistent identifiers, cross-service tracking or individual profiling.
Reading this browser’s preference.
Changing this setting reloads the page so the analytics scripts use the new preference immediately. Clearing this site’s stored data also clears the opt-out.
SERVER / 04
What the service receives
We do not intentionally submit calculator inputs to a server, create server-side scenario records, or attach them to an identity. Analytics receive only the redacted and controlled information described above.
No profile to build
- No login or user account
- No cloud-saved scenario library
- No bank-data connection
- No sale of calculator inputs
Normal web delivery
The hosting platform may process ordinary request information such as an IP address, browser details, time and requested path to deliver, secure and operate the site. Its own data handling applies to that infrastructure.
The app is designed for deployment on Vercel. You can read the Vercel Privacy Notice for information about its services. Following a link to GOV.UK or another external source also takes you to that site under its own privacy terms.
LIMIT / 05
Information, not financial advice
The output is an illustration produced from the values you enter. It is not a mortgage recommendation, investment recommendation, tax opinion, valuation, affordability assessment or promise of future performance.
Verify tax with HMRC or a qualified adviser, confirm mortgage and transaction costs with the relevant providers, and consider regulated advice where appropriate. A home decision also includes risks and preferences that a financial model cannot capture.