#Declination is simply the difference between the value you have, and the value you want.

It's the difference between true and magnetic north.

A good map will have both marked, it will also have "grid north" marked, which may not match either. In the UK grid north is simply the line parallel to the central meridian (2° W), so the further away from there you go, the further it is from true north.

The thing to go with that is that "add" isn't really a useful word either, as you can see from the image below which is a global map of magnetic declination, sometimes you add and sometimes you subtract, or possibly add a negative number. It just depends where you are.

Image source: http://geokov.com/education/magnetic-declination-inclination.aspx

https://www.ordnancesurvey.co.uk/resources/maps-and-geographic-resources/finding-north.html

Declination is simply the difference between the value you have, and the value you want.

It's the difference between true and magnetic north.

A good map will have both marked, it will also have "grid north" marked, which may not match either. In the UK grid north is simply the line parallel to the central meridian (2° W), so the further away from there you go, the further it is from true north.

The thing to go with that is that "add" isn't really a useful word either, as you can see from the image below which is a global map of magnetic declination, sometimes you add and sometimes you subtract, or possibly add a negative number. It just depends where you are.

Image source: http://geokov.com/education/magnetic-declination-inclination.aspx

https://www.ordnancesurvey.co.uk/resources/maps-and-geographic-resources/finding-north.html

#Declination is simply the difference between the value you have, and the value you want.

It's the difference between true and magnetic north.

A good map will have both marked, it will also have "grid north" marked, which may not match either. In the UK grid north is simply the line parallel to the central meridian (2° W), so the further away from there you go, the further it is from true north.

The thing to go with that is that "add" isn't really a useful word either, as you can see from the image below, sometimes you add and sometimes you subtract, or possibly add a negative number. It just depends where you are.

Image source: http://geokov.com/education/magnetic-declination-inclination.aspx

https://www.ordnancesurvey.co.uk/resources/maps-and-geographic-resources/finding-north.html

#Declination is simply the difference between the value you have, and the value you want.

It's the difference between true and magnetic north.

A good map will have both marked, it will also have "grid north" marked, which may not match either. In the UK grid north is simply the line parallel to the central meridian (2° W), so the further away from there you go, the further it is from true north.

The thing to go with that is that "add" isn't really a useful word either, as you can see from the image below which is a global map of magnetic declination, sometimes you add and sometimes you subtract, or possibly add a negative number. It just depends where you are.

Image source: http://geokov.com/education/magnetic-declination-inclination.aspx

https://www.ordnancesurvey.co.uk/resources/maps-and-geographic-resources/finding-north.html

#Declination is simply the difference between the value you have, and the value you want.

It's the difference between true and magnetic north.

A good map will have both marked, it will also have "grid north" marked, which may not match either. In the UK grid north is simply the line parallel to the 0 meridian, so the further away from there you go, the further it is from true north.

The thing to go with that is that "add" isn't really a useful word either, as you can see from the image below, sometimes you add and sometimes you subtract, or possibly add a negative number. It just depends where you are.

Image source: http://geokov.com/education/magnetic-declination-inclination.aspx

https://www.ordnancesurvey.co.uk/resources/maps-and-geographic-resources/finding-north.html

#Declination is simply the difference between the value you have, and the value you want.

It's the difference between true and magnetic north.

A good map will have both marked, it will also have "grid north" marked, which may not match either. In the UK grid north is simply the line parallel to the central meridian (2° W), so the further away from there you go, the further it is from true north.

The thing to go with that is that "add" isn't really a useful word either, as you can see from the image below, sometimes you add and sometimes you subtract, or possibly add a negative number. It just depends where you are.

Image source: http://geokov.com/education/magnetic-declination-inclination.aspx

https://www.ordnancesurvey.co.uk/resources/maps-and-geographic-resources/finding-north.html