How Project Index calculates contractor rates

We collect rates from relevant current UK contract opportunities — advertised day rates for the roles we cover, gathered on a rolling basis from job boards, frameworks and direct employer adverts.

Advertised rates show what the market is asking for right now, which makes them the freshest signal available. They can sit slightly below what the strongest candidates ultimately secure, so they are weighted as one input rather than the whole picture.

Where available, we incorporate data from specialist recruitment firms working in power, energy, rail, data centre and industrial markets.

Recruiters see placed rates — what candidates actually accepted — not just the rate advertised. This helps correct the gap between advertised and achieved rates, particularly for scarce skills.

Contractors share their current rate anonymously through this site: role, day rate, region, IR35 status, experience, sector and specialism, with the submission date recorded automatically.

Submissions are the ground truth of our dataset — actual rates, not asking rates. Each one is stored anonymously and used only in aggregate. As the contributor base grows, reported rates carry increasing weight in every benchmark.

Before any rate informs a benchmark, we remove duplicates, obvious entry errors and statistical outliers — both implausibly low and implausibly high values for the role in question.

Submissions that are incomplete, inconsistent or fall outside a plausible band for the role are excluded. No individual submission is ever displayed; only cleaned, aggregated results appear on the site.

Cleaned data is segmented by role, region, sector, experience level and IR35 status.

A Commissioning Engineer on a data centre programme and one commissioning 33kV protection schemes are different markets — segmentation is what stops a single blended average hiding that. Regional figures apply consistent adjustment factors; experience bands reflect how rates scale across a career.

The headline figure shown on each role page — the market benchmark — represents the central market rate identified from the cleaned dataset and available market evidence. It is built from advertised vacancies, specialist recruitment data and contractor submissions, weighted by how much reliable information exists for that role.

As contractor submission volumes increase, reported rates carry greater weight in the benchmark. Once a role has enough observations, the benchmark becomes the median of reported contractor rates and we will say so explicitly — for example, “Median contractor rate: £710/day — based on 184 observations” — rather than implying a precision the data cannot yet support.

The typical range shows the spread of the cleaned data around that central rate. All figures are indicative: they are planning benchmarks, not quotes, and individual contracts vary with scope, duration, shift patterns and client.

Every benchmark is reviewed weekly against fresh vacancy data, recruitment market signals and new contractor submissions.

Each role page carries its own “Last reviewed” date so you can see exactly how current a figure is. When a benchmark moves, the date moves with it — if the market shifts, this site shifts the same week.

A benchmark is only shown when there is enough reliable information to support it. Where data for a role, region or segment is thin, we say so rather than publish a precise-looking number.

Ranges widen and confidence falls in thin segments; figures in those areas lean more heavily on vacancy and recruitment data until contractor submissions build up. We would rather show an honest indicative range than a false point of precision.

Every benchmark carries a data confidence indicator — High confidence, Good confidence or Developing data — together with the number of market observations behind it, so you can see at a glance how established each figure is.