Our Methodology
How we collect, process, and present UK crime data.
Data Sources
Police.uk Open Data
Street-level crime and outcome data published monthly by UK police forces. Data covers 43 police forces in England and Wales.
Reporting lag: 1-2 months
ONS Census 2021 & 2011
Resident and workday population data at LSOA, MSOA, Ward, and local authority level. Both 2021 and 2011 Census workday figures are used to produce accurate crime rates.
Updated: Decennial
HM Land Registry
Property transaction data including sale prices, property types, and transaction dates.
Updated: Monthly
Open Government Licence
All data is published under the Open Government Licence v3.0, ensuring transparency and reusability.
Crime Rate Calculation
To ensure stability and authority, our primary safety metrics are calculated using a 12-month rolling annualised rate. This eliminates the volatility of single-month spikes (e.g., a one-off event) and provides a realistic view of an area's safety. The formula:
Effective Population — Why It Matters
Using only resident population as the denominator produces severely misleading rates for city-centre areas. Westminster, for example, has around 204,000 residents — but on any given weekday its streets are used by over 2.5 million people (workers, commuters, visitors). Dividing crimes by 204,000 inflates the rate by more than tenfold compared to the actual risk to any individual present.
To correct for this, we use an effective population that automatically selects the most appropriate denominator for each area:
Residential suburbs — resident population is highest, so it is used. Rates are unchanged from a traditional calculation.
City centres (Westminster, City of London) — workday population greatly exceeds resident population and is used instead, producing realistic rates.
2011 workday data as a supplement — ONS 2021 workday figures were collected during the COVID-19 pandemic, when widespread home-working significantly reduced office populations. Where the 2011 workday figure is higher, we use that instead to better reflect normal-year activity levels.
Population data is sourced from ONS Census 2021 and 2011 at LSOA level and aggregated upward to MSOA, Ward, postcode district, and local authority. Workday population represents the number of people present in an area during working hours — including in-commuters — as measured by the Census.
Ranking System
Our intelligence engine ranks areas based on their 12-month stability:
National Safety Rank
A stable rank comparing all 331 UK cities based on their 12-month rolling crime rate.
National Percentile
For Wards and MSOAs, we use percentiles (e.g., "Top 5% Safest") to provide meaningful national context among 7,500+ areas.
Local Rank
Direct comparison of Wards/MSOAs within their parent city to identify the safest local neighbourhoods.
Limitations & Disclaimers
Reporting lag: Police.uk data has a 1-2 month delay. The "latest month" shown on our platform reflects the most recent data released by police forces, not the current calendar month.
Location accuracy: Street-level crime locations are anonymised to the nearest map point by Police.uk. Crimes are mapped to approximate locations, not exact addresses.
Under-reporting: Not all crimes are reported to police. Published statistics represent recorded crime only and may under-represent actual crime levels.
Quick Reference
Questions about our data?
We are committed to transparency. If you have questions about our methodology or data sources, please get in touch.
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