mathematics

International Territorial Level

International Territorial Level is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand International Territorial Level rather than just read about it. In short: International Territorial Level (ITL) is a geocode standard for referencing the subdivisions of the United Kingdom for statistical purposes, used by the Office for National Statistics (ONS). From 2003 and until 2020 it functioned as part of the European Union and European Statistical System's geocode standard Nomenclature of Territorial Units for Statistics or NUTS.

Key takeaways

International Territorial Level belongs to mathematics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect International Territorial Level to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of International Territorial Level from memory before moving on to harder problems.

Reference excerpt

International Territorial Level (ITL) is a geocode standard for referencing the subdivisions of the United Kingdom for statistical purposes, used by the Office for National Statistics (ONS). From 2003 and until 2020 it functioned as part of the European Union and European Statistical System's geocode standard Nomenclature of Territorial Units for Statistics or NUTS. Following Brexit, the ONS set to develop a domestic statistical classification framework separate from NUTS. Initially, the ITLs were a mirror to the pre-existing NUTS system, they retained the same three level hierarchy and boundaries used for NUTS in the United Kingdom from 2018. ITLs were set to follow a similar review timetable to NUTS, being reviewed every three years. The ONS developed new official GSS codes of ITL geography aligned with the existing NUTS codes. From 1 January 2021, the ONS encouraged "ITL" be used as a replacement to the "NUTS" designation, with lookups between NUTS and ITL maintained and published until 2023. The current ITL classification since 2025, has 12 regions at ITLs 1, 46 at ITL 2 and 182 at ITL 3. The first ITL classification in 2021, following Brexit, was a mirror of the previous NUTS classification with slight modification, the ONS listed 12 regions at ITL 1, 41 regions at ITL 2, and 179 regions at ITL 3. "UK" in the NUTS codes were replaced with "TL". The last NUTS classification is dated 21 November 2016 and was effective from 1 January 2018, listed 12 regions at NUTS 1, 40 regions at NUTS 2, and 174 regions at NUTS 3 level.

List of ITL regions

2025 The current ITL classification since 2025, has 12 regions at ITLs 1, 46 at ITL 2 and 182 at ITL 3.

Level 2

2021 ITL Following Brexit, the classification used by the ONS was replaced with ITLs. Between 2021 and the next review scheduled for 2024, the ITLs were a mirror of the NUTS classification adopted in 2018 (see below). All NUTS codes containing "UK" were changed to use "TL" for Territorial Level.

Former NUTS regions

2018 NUTS

2016 NUTS UKM2 (Eastern Scotland) was replaced with UKM7 (Eastern Scotland) along with associated NUTS 3 areas UKM3 (South Western Scotland) was replaced with UKM8 (West Central Scotland) and UKM9 (Southern Scotland)

2015 NUTS

2013 NUTS NUTS 2013 came into force on 1 January 2015. 2015 changes to NUTS 3 areas without changes to NUTS 2 areas:

UKJ42 (Kent CC) was replaced by UKJ43 (Kent Thames Gateway) UKJ44 (East Kent) UKJ45 (Mid Kent) UKJ46 (West Kent) UKJ23 (Surrey) was replaced by UKJ25 (West Surrey) and UKJ26 (East Surrey) UKJ24 (West Sussex) was replaced by UKJ27 (West Sussex South West) and UKJ28 (West Sussex North East) UKJ33 (Hampshire CC) was replaced by UKJ35 (South Hampshire), UKJ36 (Central Hampshire), UKJ37 (North Hampshire) UKD43 (Lancashire CC) was replaced by UKD44 (Lancaster and Wyre), UKD45 (Mid Lancashire), UKD46 (East Lancashire) and UKD47 (Chorley and West Lancashire) UKD31 (Greater Manchester South) was replaced by UKD33 (Manchester), UKD34 (Greater Manchester South West) and UKD35 (Greater Manchester South East) UKD32 (Greater Manchester North) was replaced by UKD36 (Greater Manchester North West) and UKD37 (Greater Manchester North East) UKH13 (Norfolk) was replaced by UKH15 (Norwich and East Norfolk), UKH16 (North and West Norfolk) and UKH17 (Breckland and South Norfolk) UKH33 (Essex CC) was replaced by UKH34 (Essex Haven Gateway), UKH35 (West Essex), UKH36 (Heart of Essex) and UKH37 (Essex Thames Gateway) In 2015 the Greater London NUTS 1 area was left unchanged however the previous NUTS 2 area of inner and outer London were abolished and with the previous NUTS 3 areas becoming NUTS 2 areas. Thus NUTS 2 of Inner London West UKI11 becoming the NUTS 3 area of UKI3 and likewise: Inner London East (from UKI12 to UKI4), Outer London East and North East (from UKI21 to UKI5), Outer London South (from UKI22 to UKI6) and Outer London West and North West (from UKI23 to UKI7). The NUTS 3 areas were now a single or a group of two or three boroughs.

2010 NUTS NUTS 2010 came into force on 1 January 2012. 2010 changes to NUTS 2 also resulting in changes with NUTS 3 regions

The combined area of UKD2 (Cheshire pre-2010) and UKD5 (Merseyside pre-2010) were replaced by UKD6 (Cheshire post-2010) and UKD7 (Merseyside post-2010), due to the transfer of Halton to the Merseyside NUTS region from Cheshire. This resulted in the following changes to the underlying NUTS 3 areas: UKD22 (Cheshire CC) being split into UKD62 (Cheshire East) and UKD63 (Cheshire West and Chester); The areas of Liverpool, Sefton and Wirral were not changed as NUTS 3 areas however to reflect their transfer within NUTS 2 areas were respectively renumbered from (UKD52 to UKD72; UKD53 to UKD 73 and UKD54 to UKD 74). The two areas of UKD51 (East Merseyside pre 2010) and UKD21 (Halton and Warrington) were amended by the transfer of Halton from the latter to former to form the new areas of UKD71 (East Merseyside post-2010) and UKD61 (Warrington). 2010 changes to NUTS 3 areas without changes occurring to NUTS 2 areas

UKE43 (Calderdale, Kirklees and Wakefield) was replaced by UKE44 (Calderdale and Kirklees) and UKE45 (Wakefield) UKF23 (Northamptonshire) was replaced by UKF24 (West Northamptonshire) and UKF25 (North Northamptonshire) UKG34 (Dudley and Sandwell) was replaced by UKG36 (Dudley) and UKG37 (Sandwell) UKG35 (Walsall and Wolverhampton) was replaced by UKG38 (Walsall) and UKG39 (Wolverhampton). Bedfordshire CC UKH22 was replaced by UKH24 (Bedford) and UKH25 (Central Bedfordshire)

2006 NUTS NUTS 2006 came into force on 1 January 2008.

2003 NUTS In the first version in 2003, North Eastern Scotland (which then included part of Moray) was coded UKM1, and Highlands and Islands was coded UKM4. The codes in this scheme start with "UKC" to avoid confusion with codes in the previous system, which identified 11 regions of England using codes that started with "UK1" through "UK9" plus "UKA" and "UKB".

Demographic statistics by ITL 1 region The 12 ITL regions of the United Kingdom are listed below. Population numbers are for mid-2019 (as NUTS 1), and areas are in square kilometres. Data is from the Office for National Statistics.

Local administrative units

Below the ITL levels, the two LAU (Local Administrative Units) levels are:

The two LAU levels are maintained by the UK Office for National Statistics within the ONS coding system. The LAU codes of the United Kingdom can be downloaded here: [1]

Illustrations

Worked examples

Example 1 — a first encounter with International Territorial Level

Start with the simplest possible case. Write down what International Territorial Level claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to International Territorial Level before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about International Territorial Level ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of International Territorial Level

In research: International Territorial Level appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses International Territorial Level in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: International Territorial Level is common in secondary-school and first-year university syllabi. It links to neighbouring topics NUTS statistical regions of the United Kingdom, Nomenclature of Territorial Units for Statistics, Types of subdivision in the United Kingdom, so understanding it makes those chapters shorter.
In everyday life: Look for International Territorial Level outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study International Territorial Level in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what International Territorial Level means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain International Territorial Level out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is International Territorial Level in simple terms?

Why does International Territorial Level matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study International Territorial Level?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on International Territorial Level.