Methodology
Sources & Methodology
Links last checked: August 2026
Every calculator on this site starts with default numbers for each country and city — typical home prices, rents, mortgage rates, and closing costs. These defaults are illustrative estimates, not a live data feed, and every one of them is editable — the calculators are built to be adjusted to your actual numbers, not relied on as-is.
For anyone who wants to verify or update those figures themselves, here's where this type of data is officially published for each country we cover. These are the same kinds of sources we use when setting our defaults, and we recommend checking them directly for current rates before making a real decision.
Cross-country / General
- Numbeo — Price to Rent Ratio Rankings
Live, crowdsourced price-to-rent ratios by city worldwide. User-submitted, not an official government source, but continuously updated — useful for checking current numbers against our illustrative defaults.
- Dotsis, Petris & Psychoyios (2025), Journal of Real Estate Finance and Economics
Peer-reviewed study of 18 countries over 1870–2020 finding the rent-to-price ratio to be the strongest predictor of housing market crashes — the basis for the "elevated ratio" warning on our rent-to-buy ratio calculator.
- FHFA House Price Index — long-term nominal average
Basis for the US "annual home appreciation" default of 4.3% (long-term nominal average, 1975–2025).
- Nationwide / ONS UK House Price Index — long-term average
Basis for the UK default of 3.5% nominal — long-run financial-planning estimates typically use 3–4%.
- Deutsche Bundesbank — residential property prices
Basis for the Germany default of 2% — German house prices fell in 2022–2024 after a 2010–2021 boom, so we use a conservative long-term figure rather than the recent correction or the earlier boom.
- Notaires–INSEE housing price index (France)
Basis for the France default of 2.5% — recent (2025–2026) growth has been closer to flat (~0.5–1% YoY), so this default sits on the conservative end of the long-term range.
- CRISIL / NoBroker — India residential price trends
Basis for the India default of 6% — the reported 20-year national average; tier-1 cities (Mumbai, Delhi, Bengaluru) have historically run higher, at roughly 6–10%.
- FipeZap Properties Asking Price Index (Brazil)
Basis for the Brazil default of 9% nominal — the reported 2008–2023 average annual nominal appreciation tracked by FipeZap.
United States
- Freddie Mac Primary Mortgage Market Survey
Weekly average mortgage rates.
- IRS
Federal tax treatment of mortgage interest and property.
- National Association of Realtors
Home price and market data by metro area.
United Kingdom
- HM Revenue & Customs — Stamp Duty Land Tax
Official current SDLT rates and thresholds, including the additional-property surcharge.
- Bank of England
Base rate and mortgage market data.
- HM Land Registry
UK house price index by region.
Brazil
- Banco Central do Brasil
SELIC rate and mortgage/financing market data.
- Receita Federal
Federal tax rules relevant to property.
- IBGE — diretório de municípios
ITBI rates are set at the municipal level — use this directory to find your city hall's official site and current rate.
India
- Reserve Bank of India
Repo rate and home loan market data.
- RERA (state regulator)
Project registration status — check your state's RERA portal.
- India.gov.in — National Portal
Directory of state government services, including each state's stamp duty & registration department — rates vary significantly by state.
Germany
- Deutsche Bundesbank
Mortgage rate and housing market data.
- Bundesministerium der Finanzen
Federal tax rules relevant to property.
- Statistisches Bundesamt (Destatis)
Publishes Grunderwerbsteuer (property transfer tax) rates by Bundesland — they range roughly 3.5–6.5% depending on the state.
France
- Notaires de France
Frais de notaire (notary fees) and property price data.
- Banque de France
Mortgage rate and lending market data.
- Service Public — impots.gouv.fr
Property tax rules (taxe foncière).
Notice a default that's out of date? Let us know — see also our disclaimer for how these estimates should (and shouldn't) be used.