Gera Cost Comparison Delta β methodology and data sources
This page explains exactly how the Gera Cost Comparison Delta (GCCD) is calculated, what data it uses, and what its limitations are. Reproducibility and transparency are non-negotiable β every number on a GCCD page traces to a real, citable source.
The GCCD formula
Where midpointA and midpointB are the arithmetic means of each trade's national typical hourly rate band, expressed in nominal 2026 Β£/hr. Day-rate trades (painters, carpenters, plasterers) are converted to an hourly equivalent by dividing the day-rate midpoint by 8 hours. The result is a positive percentage: βtrade A costs X% more per hour than trade B.β
Full methodology
The Gera Cost Comparison Delta (GCCD) is a pairwise hourly-rate premium index comparing two UK home service trades. It is computed as:
GCCD = ((midpointA β midpointB) / midpointB) Γ 100
where midpointA and midpointB are the arithmetic means of each trade's national typical hourly rate band, as published in the GeraHome UK Trade Cost Guides 2026 (compiled from publicly available UK tradesperson rate surveys). Day-rate trades (painters, carpenters, plasterers) are converted to an hourly equivalent by dividing the day-rate midpoint by 8 hours.
The rates are expressed in nominal 2026 terms, consistent with ONS CPIH services sub-index CP0432 (Services for maintenance and repair of the dwelling), which stood at 110.6 (2015=100) in January 2026 β up 0.6% year-on-year. This index is cited for context only; the trade rates themselves are already 2026 survey figures so no mechanical inflation adjustment is applied to the headline GCCD.
Limitations: GCCD reflects national typical rate midpoints. Actual quotes vary by region (London/SE typically 20β40% above national average), job complexity, access, materials, time of day, and whether the trade is an independent or agency. The index is not a price guarantee. Always obtain an upfront, itemised quote.
Data: ONS CPIH01 v67 (OGL v3.0, published 18 February 2026, data to January 2026). GeraHome cost-guide cluster (published ranges, GeraHome.com/cost-guides).
ONS CPIH sub-indices used
Source: Office for National Statistics β CPIH01 dataset Β· version 67 Β· published 18 February 2026 Β· data to January 2026.
| Code | Series | Jan-26 | YoY change |
|---|---|---|---|
| CP043 | 04.3 Maintenance & repair of dwelling | 121.7 | +0.5% |
| CP0431 | 04.3.1 Materials | 132.4 | +0.2% |
| CP0432 | 04.3.2 Services β used for GCCD context | 110.6 | +0.6% |
| CP0533 | 05.3.3 Repair of household appliances | 123.8 | β |
| CP056 | 05.6 Goods & services for routine maintenance | 132.1 | β |
Index: 2015 = 100. YoY = Jan-25 β Jan-26.
Data licence
ONS CPIH01 data is published under the Open Government Licence v3.0. Contains public sector information licensed under the Open Government Licence v3.0. Trade cost ranges are published GeraHome survey-compiled data (GeraHome.com/cost-guides).
ONS CPIH01 v67 fetched 2026-06-20 from api.beta.ons.gov.uk.
Limitations and caveats
- National averages only: GCCD reflects national typical rate midpoints. London and the South East typically run 20β40% above the national average; the North, Midlands, Wales and Scotland below it.
- Hourly comparison only: Pest controllers and drainage specialists are excluded from the hourly GCCD because their work is priced per treatment or per job, not per hour. See the full cost-guide pages for those trades.
- Not a price guarantee: Actual quotes depend on job complexity, access, materials, time of day, and whether the trade is an independent or agency. Always obtain an upfront, itemised quote.
- NHS-vs-private comparison: This cluster does not include NHS versus private healthcare cost comparisons. Provider-published private list prices were not available from a key-free, non-aggregator source at time of build.
- Refresh cadence: ONS CPIH data is released monthly; trade survey rates are reviewed annually. This cluster's data reflects January 2026 CPIH and 2026 trade cost surveys.
Compare trade costs now
Use the interactive GCCD tool to compare any two UK trades and understand the typical cost premium before you get quotes.
See all trade comparisons