Compass Zones: How Many Norths Are There?
Ask a walker which way north is and you will usually get a confident point. Ask which north, and things get interesting. There are three, and your compass also has a hemisphere to think about.
If you have ever stood on a hill with a map in one hand and a compass in the other, wondering why the two do not quite agree, you are in good company. It is one of the questions we hear most on our map and compass courses, and it is a good one. The short answer is that there are three norths, and they are not the same thing.
The Three Norths
True north is the direction of the geographic North Pole. All the lines of longitude on a globe run towards it.
Grid north is the direction the vertical blue grid lines on an Ordnance Survey map point. The grid is flat, while the Earth is curved, so grid north matches true north exactly only along one line of longitude (2 degrees west of Greenwich for the OS grid).
Magnetic north is where your compass needle points, following the Earth's magnetic field. It is not fixed. It wanders slowly from year to year.
| North | What it is | Where you will find it |
|---|---|---|
| True north | Direction of the geographic North Pole | Lines of longitude, the Pole Star |
| Grid north | Direction of the map's vertical grid lines | Blue lines on OS maps |
| Magnetic north | Direction a compass needle settles | Your compass |
Why Does This Matter on a Walk?
The gap between grid north and magnetic north is called the grid-magnetic angle. If you take a bearing from the map and follow it with your compass, that angle is the small error you need to allow for. Over a short, clear path you may never notice. Over a long moorland leg in mist, a few degrees can put you a fair distance off line.
That is why the map's margin gives the grid-magnetic angle and how it changes each year. It is worth reading it every time, and checking the date of the map.
A Rare Moment for Britain
Here is a lovely bit of navigation trivia. In November 2022, all three norths lined up over England for the first time since records began, starting at Langton Matravers in Dorset. Because magnetic north keeps drifting, the point of alignment travelled up the country over the following years, and the British Geological Survey predicted it would leave England at Berwick-upon-Tweed in December 2025, right on our Northumberland doorstep. It is expected to reappear on Scottish land around late October 2026bgs . It will probably be hundreds of years before it happens again.
What it means for you: in the north of England the three norths are currently very close together, so the correction is small. Do not let that make you complacent. Check the map margin, and remember that it will be different in other parts of the UK and abroad.
And Now the Hemisphere Bit: Compass Zones
The Earth's magnetic field does not run flat along the ground. Near the equator it does, but the further you travel from it, the more the field tilts downwards towards the ground (this is called magnetic dip). A compass needle that is balanced for one part of the world will tilt, drag or stick in another.
To deal with this, manufacturers balance their compasses for particular parts of the world. Silva, for example, balances most of its compasses for one of three magnetic zones: MN (Magnetic North), ME (Magnetic Equator) or MS (Magnetic South). The northern zone, MN, covers Sweden, the Nordic countries and large parts of Europe and North America, which means the UK. Some compasses have a global needle that works in all three zones, which makes them a great choice for travel. Other makers use different systems (Suunto, for example, use two zones), and there is no industry standard, so always check the maker's own guidance.hop
Top tip: if you are travelling abroad, particularly to the southern hemisphere, check the zone printed on or listed for your compass. A UK compass can work reasonably well a long way from home, but in a very different zone the needle may dip and stick.
Practical Tips From the Hill
Check the date of your map and read the grid-magnetic angle in the margin. Keep your compass away from phones, watches, car bonnets and anything magnetic, as these can send the needle astray. Hold the compass flat so the needle swings freely. And if you are heading overseas, check the compass zone before you pack.
Frequently Asked Questions
How many norths are there?
Three that matter to walkers: true north, grid north and magnetic north.
Do I need to adjust for magnetic variation in the UK?
Yes, it is good practice. The angle is small in parts of the north of England at present, but it changes with location and over time, so always check the map margin.
What is a compass zone?
It is the part of the world a compass needle is balanced for, to allow for magnetic dip.
Can I use my UK compass abroad?
Often, yes, within reason. In a very different zone the needle may tilt or stick, so check before you go.
Where can I learn to use a map and compass properly?
On one of our map and compass courses, of course.
Navigation is a skill that gets more enjoyable the more you practise. Come and join us and find your north, whichever one it is.
If you want a digital back-up, our friends at GPS Training can help you get confident with GPS too.