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Summary
The UK Affordability Map is an interactive choropleth that colours every neighbourhood in England by whether your budget can buy there. You set your salary, deposit, and a lending multiplier; the map instantly recolours ~32,800 Lower Super Output Areas (LSOAs) from green (affordable) to red (unaffordable). A toggle switches to the Index of Multiple Deprivation (IMD) overlay so you can cross-reference price with neighbourhood quality.
How it works
The affordability formula
The calculator uses a simple income-multiple model, the same shorthand lenders use for initial mortgage sizing:
| Variable | Meaning | Default |
|---|---|---|
| Salary | Gross annual income | £35,000 |
| Deposit | Cash savings for down payment | £25,000 |
| Multiplier | How many times your salary a lender will lend | 4.5× |
Total budget = (salary × multiplier) + deposit
For example: (£35,000 × 4.5) + £25,000 = £182,500
Affordability bands
Each LSOA has a median sold price computed from all Land Registry transactions in that area. The map compares your budget to each LSOA’s median:
| Ratio (budget ÷ median) | Band | Colour |
|---|---|---|
| ≥ 1.0 | Affordable | Green |
| 0.9 – 1.0 | Near-affordable | Lime |
| 0.8 – 0.9 | Upper stretch | Yellow |
| 0.75 – 0.8 | Lower stretch | Orange |
| < 0.75 | Unaffordable | Red |
| No data | Insufficient transactions | Grey |
What mortgage multipliers mean
UK lenders typically offer 4 to 4.5 times gross annual salary. Some specialist lenders go up to 5–5.5× for high earners or professionals. The FCA tracks average loan-to-income ratios; the market mean sits near 3.5× across all borrowers, but first-time buyers often push to 4.5×.
The multiplier slider lets you explore: conservative (3×) vs. stretched (5.5×) borrowing.
What is an LSOA?
Lower Super Output Areas are the finest-grained geographic units the ONS publishes. Each covers roughly 1,500 people (400–1,200 households). England has 32,844 LSOAs. They were defined for the 2011 Census and are the join key for IMD 2019 data.
Index of Multiple Deprivation (IMD)
The IMD 2019 ranks every LSOA in England from 1 (most deprived) to 32,844 (least deprived), then groups them into deciles (1 = most deprived 10%, 10 = least deprived 10%).
Seven domains
IMD combines seven weighted domains:
- Income (22.5%) — proportion of population on low income
- Employment (22.5%) — involuntary exclusion from work
- Education (13.5%) — skills and training deprivation
- Health (13.5%) — premature death, disability, mental health
- Crime (9.3%) — recorded crime rates
- Housing & Services (9.3%) — overcrowding, affordability, access to services
- Living Environment (9.3%) — housing quality, air quality, road safety
Toggling to the IMD view lets you see, at a glance, whether a cheap area is cheap because it is deprived or simply less popular.
Data sources
All datasets are published under the Open Government Licence v3.0:
- Property prices: HM Land Registry Price Paid Data — every residential sale in England & Wales since 1995. We aggregate all transactions per LSOA and compute the median. LSOAs with fewer than 10 transactions are excluded.
- Boundaries: ONS Open Geography Portal — LSOA 2011 Super Generalised Clipped boundaries (simplified for fast rendering).
- Deprivation: MHCLG English Indices of Deprivation 2019, File 7 (all ranks, deciles, and scores).
- Postcode lookup: ONS National Statistics Postcode Lookup (NSPL) — maps 1.7M postcodes to LSOA codes.
Technical notes
- The map uses MapLibre GL JS (open-source) with PMTiles (a single static file served via HTTP range requests). No tile server or API is needed.
- All recolouring happens client-side on the GPU — when you drag a slider, MapLibre re-evaluates a data-driven paint expression against each polygon. No network calls.
- The map is lazy-loaded: the ~10 MB PMTiles file and MapLibre JS bundle are only fetched when you click “Open Map”, keeping the initial page load fast.
Limitations
- Median prices are historical aggregates — they reflect all transactions, not just recent ones. Low-transaction LSOAs may have stale medians.
- IMD is 2019 data — the most recent available. Neighbourhood deprivation can shift, especially post-pandemic.
- Income multiples are a simplification — real lender affordability assessments consider your expenses, credit history, property type, and stress-tested interest rates.
- England only — LSOA boundaries and IMD 2019 cover England. Scotland, Wales, and Northern Ireland use different geographic and deprivation frameworks.