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How accurate is the England Peat Map? What national peat maps support at site scale

For land agents, estate managers and peat and soils consultants in England

Natural England publishes accuracy figures for the England Peat Map and describes its predictions as stronger for regions and counties than for individual sites. For a decision on one site, the published guidance points to peat depth measured on the ground.

By the Vireo teamPublished 10 November 202613 minute readSources checked 10 November 2026

England Peat Map accuracy: peat depth on a site | Vireo

Key points

The England Peat Map final depth prediction has a root mean square error of 30.9 cm and a mean absolute error of 20.8 cm. Source: Natural England Research Report NERR149, Table 7-5, May 2025.
Defra guidance sets out a depth check for a planned burn: measure and record peat depth at 5 points for every 2,500 m². Source: Heather and grass burning: rules and when you need a licence, updated 30 September 2025.
A Peatland Code baseline starts from "a 100 x 100m grid overlay", with depth and condition assessed "at each survey point". Source: Minor revisions and clarification guidance for Version 2.1 of the Peatland Code, June 2026.

A burn plan in England now turns on one question: is the peat deeper than 30 cm. Since 30 September 2025 that is the threshold in law. Regulation 3 of The Heather and Grass etc. Burning (England) Regulations 2021 covers burning "on peat that is of a depth of more than 30 centimetres".

11,047 km²

Against: Peaty soil in England, as mapped
Source: Natural England, NERR149 summary, May 2025
Date: Checked 10 Nov 2026

10 m pixels

Against: Smallest mapped area of peaty soil: 300 square metres
Source: Natural England, TIN226 user guide, May 2025
Date: Checked 10 Nov 2026

676,628 hectares

Against: Deep peat covered by the burning rules at the 30 cm threshold
Source: Defra press release, 9 September 2025
Date: Checked 10 Nov 2026

What Natural England says the map is for

The England Peat Map is a national set of modelled layers for the extent, depth and condition of peaty soil. The England Peat Map (NERR149) publication page, dated 9 May 2025, says it was built mainly to support the England Peat Action Plan. All outputs are published under the Open Government Licence.

The user guide, Technical Information Note TIN226 (May 2025), says the models exist "to make predictions about the location, quantity and condition of peat in England." It sets out how far those predictions carry at each scale.

The outputs "should be seen as giving stronger predictions at broader scales, such as whole regions or counties".
They give "weaker predictions at finer scales such as individual sites."
An individual prediction, such as a single 10 m square, "maybe very different to an observation on the ground". The guide adds that "the prediction will be closer to the real world as scale broadens out."
The guide is clear that the map still has a use on a site: "This does not mean that the outputs should be disregarded for specific sites, or in lowland environments". At that scale they are to be "viewed as indicative".

The Natural England blog, A new peat map for England (12 May 2025), makes the same point. It calls the map "a vital part of the decision-making toolkit" that "needs to be used in conjunction with local evidence for site-level decisions."

Two further statements come from the comments under that post, not from the post itself. In a reply to a reader on 13 May 2025, Natural England wrote that the map "should not be used as a stand-alone justification for action at a given site."

The same comment reply says: "It is not a regulatory mechanism and wouldn't be used by itself without first-hand verification of the situation on site."

How accurate is the map, as published?

Natural England reports the accuracy of each layer separately, and extent scores higher than depth. The figures are Natural England's own, measured on its own survey data.

For depth, the NERR149 Final Report (May 2025), section 7.4, says Natural England "evaluated models using 25% of the data held back from training." The data are the soils field data the models were trained on.

TIN226 explains the principle: some survey data "is held back from this process and used to check how accurate model predictions are."

Layer	Published measure	Published figure	Where it is published
Peaty soil extent	Overall accuracy at the 0.4 probability threshold	0.954 (sensitivity 0.964, specificity 0.951)	NERR149 Annex 6, Table 3-4
Peaty soil depth, final prediction	Root mean square error (RMSE)	30.9 cm	NERR149, Table 7-5
Peaty soil depth, final prediction	Mean absolute error (MAE)	20.8 cm	NERR149, Table 7-5
Vegetation and land cover	Overall accuracy	94%	Natural England blog, 12 May 2025

Table 1. Accuracy figures for the England Peat Map as published by Natural England. Sources: NERR149 Final Report and NERR149 Annex 6, Technical Supplement (both May 2025), and the blog cited above.

MAE is the average size of the gap between predicted and measured depth. RMSE is a related measure that gives large misses more weight. Both come from the same held-back test, and both describe the map as a whole.

For a local view, the map carries a depth confidence layer. TIN226 says it "shows how confident we are in the predicted depth for each 10 km square". The value "is only a guide to the level of confidence in each area."

NERR149 also names where the evidence is thinner. Its summary says "there is uncertainty in the lowlands, where there is less data". Where a known peat site is not predicted, "this will normally reflect a lack of survey data".

One user group has raised accuracy at field level. In the NFU statement on the map (20 May 2025, updated 27 May 2025), Deputy President David Exwood said some members had raised concerns about inaccuracies. He said: "In several areas, peat is being shown where it doesn't exist and omitted where it does."

Natural England's published route for corrections is new survey data. Its comment reply of 13 May 2025 under the blog says the update process "is in development but will include the opportunity to provide new peat survey data."

What does the 30 cm burning rule ask you to measure?

The burning guidance points to peat depth measured on the ground. The Defra and Natural England guidance is Heather and grass burning: rules and when you need a licence (updated 30 September 2025). It says you can check that you are complying with the regulations by "measuring and recording the peat depth at places you're planning to burn."

The method is short. "Follow these steps to measure peat depth for every 2,500m² (0.25 hectares)":

Photograph the equipment

"Take a photograph of the equipment you're using to measure peat depths, for example a measuring stick."

Set out five points

"Identify the position of the 4 outer corner points and the centre point of the burn."

Record where they are

Record the 5 points "using GPS coordinates or an 8-figure Ordnance Survey (OS) grid reference."

Measure and record

"Measure and record the peat depths at each of the 5 points."

The guidance names the Defra MAGIC map for checking whether land is in a less favoured area. As opened on 10 November 2026, neither that page nor the Defra licence application page (updated 30 September 2025) names a peat map for depth.

The Defra press release of 9 September 2025 says the change "redefines deep peat from the current 40cm to 30cm depth" and covers 676,628 hectares. In the government response to the consultation (9 September 2025), Defra notes that "peat shallower than 30cm is hard to reliably identify".

National peat maps across the UK and Ireland

Each nation publishes its own peat map, and each publisher states a different purpose and scale. The maps also define peat differently.

Map and publisher	Year	Stated purpose	Stated resolution or accuracy
England Peat Map, Natural England	2025	"to make predictions about the location, quantity and condition of peat in England."	10 m pixels. Extent accuracy 0.954. Depth RMSE 30.9 cm, MAE 20.8 cm.
Carbon and Peatland 2016 map, NatureScot	2016	"a high-level planning tool to promote consistency and clarity"	Indicates likely peat "at a coarse scale". No accuracy figure on the pages opened.
Peatlands of Wales map, Welsh Government	2022	To "identify areas warranting dedicated peat surveys", among other uses	50 m grid. An evidence score gives the confidence that peat is present in each cell.
Derived Irish Peat Map version 2, Environmental Protection Agency Ireland	On the EPA portal since 2010	"a long-term tool for updating national peat soil map data"	"The producer, user and overall accuracies are 88%, 91% and 85%, respectively."
Irish peat soils map, Gilet and others, Geoderma	2024	A basis "for implementing or updating national and international regulations"	"83 % for overall accuracy and F1 score for peat areas"

Table 2. National peat maps, in each publisher's words. Sources: TIN226 and NERR149. Carbon and Peatland 2016 map record and NatureScot map page. Production of the Peatlands of Wales Map (March 2022) and Peatlands of Wales Maps record. Derived Irish Peat Map version 2 record. Gilet and others, Geoderma 447 (July 2024).

The definitions differ. England maps peaty soil from "a thickness of at least 10 cm" (TIN226). The IUCN UK Peatland Programme news item of 15 May 2025 describes the map as covering "all depth measurements above 0 cm". Wales maps peat as "more than 40cm of organic material within the upper 80cm of a soil profile", on the Natural Resources Wales Peatland Data Portal page. The burning rule in England sits at 30 cm.

Scotland states the limit of use most directly. The map record says: "The map should not be used in development management decision-making." It adds: "A detailed site survey and EIA will be required."

Which source supports which decision

The published guidance follows one pattern. A national map supports the first look and the survey plan. A measured survey supports the decision. The tool below shows the wording for each case.

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Which source supports which decision

Choose the decision in front of you. The tool shows the kind of source the published guidance points to, with the wording and where it comes from.

Your decision

Every quotation is from a source cited in this article, checked 10 November 2026. Read the full guidance for your scheme before you act on it.

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Illustrative example

An invented moorland holding in a less favoured area plans three burn patches of 0.5, 0.75 and 0.25 hectares. That is 1.5 hectares, or 15,000 m². On the national map the patches cover 150 pixels of 10 m, and the depth layer reads 38 cm at the centre of the largest.

A reading of 38 cm sits 8 cm above the threshold. Natural England's published mean absolute error for the depth layer is 20.8 cm, and TIN226 treats a single pixel as "indicative". The map shows a depth question worth settling on the ground.

The guidance gives the count. The steps repeat for every 2,500 m², so the three patches need 2, 3 and 1 repeats. Six repeats of 5 points make 30 measured depths.

Figure 1. Map predictions and measured points per hectare. Arithmetic from three published figures. The 10 m pixel is from TIN226 (May 2025). The 5 points per 2,500 m² are from the Defra burning guidance (30 September 2025). The 100 x 100 m grid is from the Peatland Code clarification guidance (June 2026).

The same holding has a 60 hectare restoration area for a carbon project. A 100 m grid gives about 60 survey points. The Peatland Code guidance then adds points "when a measurement is less than 50 cm deep", at "all eight immediate neighbours of that point."

If four separate points read under 50 cm, that is up to 32 more points, and 92 in total. A map read beforehand shows where those shallow margins are likely to fall.

Have a moor, a burn plan or a grant form with a depth question on it? Send us your site and we reply within two working days.

What a site decision needs

A site decision needs measured depths that someone else can check, set beside the map reading they were compared with.

The location of every point, by GPS coordinates or an 8-figure grid reference, as the burning guidance sets out.
The precision of each reading. Natural England's Peat Probe Guidance (NERR149 Annex 3) (May 2025) says: "It is critically important that you record at what accuracy level you recorded a measurement."
Repeat readings. The same guidance says: "Take multiple depth readings within 30 cm from the original point."
The map layer and version you screened with, and its stated confidence for your 10 km square.

Probing has its own stated limits. Annex 3 says peat probing "is not accurate 100% of the time". It adds: "In general overestimates are more common than underestimates but both can happen."

The Vireo Site Evidence Pack is a desk read of a site before survey, and every figure in a pack carries its range, its source and its test label.

For a peat site, the pack shows a desk read of likely peat depth and condition. It tells the surveyor where to probe first. Coverage is the UK and Ireland, and Vireo can supply the surveys: drone, aerial and ground, including ground-penetrating radar and magnetometry.

What to do next

Open the map and its user guide together

Read the extent probability and the depth confidence layer for your land, with TIN226 beside you.

Count the points before you price the survey

Use 5 points for every 2,500 m² of planned burn, or a 100 m grid for a Peatland Code baseline, then add the shallow margins.

Send survey data back

Natural England's comment replies under its blog give peatmap@naturalengland.org.uk for new peat survey data.

Get a desk read where the margin is tight

Where the map sits close to a threshold, a read before the survey shows where the measured points matter most.

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How accurate is the England Peat Map? What national peat maps support at site scale

What Natural England says the map is for

How accurate is the map, as published?

What does the 30 cm burning rule ask you to measure?

Photograph the equipment

Set out five points

Record where they are

Measure and record

National peat maps across the UK and Ireland

Which source supports which decision

Which source supports which decision

Illustrative example

What a site decision needs

What to do next

Open the map and its user guide together

Count the points before you price the survey

Send survey data back

Get a desk read where the margin is tight

Sources

Ask the team

Ask the team about peat maps and depth

Keep reading

Peat management plan: what it must contain and what a reviewer checks

The peat depth gap: where the open measurements are

Peat surveys for wind farms and grid lines in Scotland: what the guidance asks for

See what is under your site before you survey it.

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