Where our numbers come from

How we choose and check sources

We prefer the official source. When we cannot read a number on the official page, we use a dated third-party page. When no source gives it at all, we work out our own estimate and say what it is based on. Any other figure we have not yet checked against the official page carries the “Not yet checked” label.

We review every figure at least every 90 days.

• 50 topics · 290 sources
• Reviewed 23 September 2026

What the labels mean

739 figures carry their own status label. The number next to each label is how many of them carry it.

Official source 407 figures

Read on the official page: a regulator, a government scheme, a published tariff, or the maker’s own datasheet or spec page.

Dated third-party source 119 figures

Read on a dated third-party page, such as a price survey, a retailer or a product test.

Estimate 196 figures

Our own figure, worked out from other sources. The tool says what it is based on.

Not yet checked 17 figures

Taken from a source, but not yet checked against the official page.

9 more rows record that we looked for a rebate or a fee and found none. No source can confirm that something does not exist, so these rows carry no label. Each one says the date we looked.