Safety Score Methodology

Data Source

• Police.uk Crime Data — Police-recorded crimes by street reported publicly by UK police forces
• Update Frequency — Monthly, published on the first Friday of each month
• Geographic Unit — Lower Super Output Area (LSOA) — approximately 1,500 residents per area

Calculation Method

1. Match postcode to LSOA — We geolocate each postcode's centroid to its parent Lower Super Output Area (LSOA)
2. Sum crimes per LSOA — We aggregate all police-recorded crimes in the LSOA for the most recent 12-month rolling period
3. Calculate national percentile — We rank each LSOA against all ~32,800 LSOAs in the UK by total crime count
4. Convert to 0–10 score — We map the percentile rank to a 0–10 scale where 10 = safest (0th percentile, lowest crime) and 0 = highest crime risk (100th percentile)
5. Cache for performance — Scores are cached monthly after Police.uk updates

Percentile Scoring

The Safety Score is a percentile rank, not a raw count. This means:

• A score of 9/10 means the postcode's LSOA is in the safest 10% of the UK
• A score of 5/10 means it's near the national average
• A score of 1/10 means it's in the 90th percentile for crime (higher crime than 90% of the country)

Why Percentiles?

We use percentiles because raw crime counts vary dramatically by population. A city LSOA with 30,000 residents might record 200 crimes; a rural LSOA with 1,500 residents might record 8. Percentile ranking makes scores comparable across urban and rural areas.

Limitations

• Reported Crime Only — We measure police-recorded crimes, not all crime. Reporting varies by police force and population behavior.
• LSOA-level Aggregation — Your postcode shares its score with all postcodes in the same LSOA (~600 postcodes per LSOA). Street-level variation exists but is not reflected.
• 12-month Lag — Data is published with a 2–4 week lag. Very recent crime is not captured.
• Crime Type Mix — The score combines all crime types (theft, assault, vehicle crime, antisocial behavior, etc.). It doesn't differentiate.

Interpretation

Data Attribution

Contains public sector information licensed under the Open Government Licence v3.0, sourced from Police.uk.