How does Great Circle Mapper – GCMap work?

Updated May 31, 2024
Fact checked by
Alexandrine Bertrand
Alexandrine Bertrand Alexandrine Bertrand
An avid solo traveller, Alexandrine is an expert on loyalty programmes such as Aeroplan, Avios, AIR MILES, Flying Blue and Marriott Bonvoy. With a budget-conscious approach, she helps travellers make the most of their points and miles to experience affordable, off-the-beaten-path getaways. She also shares a love of gastronomy and enjoys exploring local flavours and culinary traditions.
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Gcmap Featured
To the point Great Circle Mapper is an essential tool for people who wish to calculate distances between several destinations.

How does Great Circle Mapper - GCMap work?

Great Circle Mapper – also known as GCMap or GCM – is a tool I regularly use. It provides a wealth of information on airports and the distances between two or more destinations.

It is a particularly useful tool for flyer programs of airlines whose pricing is linked to the distance travelled. It’s the case with British Airways Executive Club or the new Air Canada Aeroplan program.

It is also an ideal tool to visually present a route on a map, which is particularly used within the milesopedia member community.

Great Circle Mapper - GCMap settings

There are several parameters to be aware of depending on your objectives.

Characters to know

Before getting to the heart of the matter, you should first know that there are four main characters to know with GCMAP:

  • A dash “” allows to link destinations together
  • A comma “,” separates the queries
  • A crossbar “/” allows to duplicate queries with the first one
  • An arobase “@” allows you to base a query from an airport

Calculate distances between destinations

To calculate distances between different destinations (and draw routes on a map ), you will essentially need to use the hyphen “-“, the comma “,” and the crossbar “/”.

Here are the different actions possible with GCMAP:

Goal Example
Travel between 2 airports – one way YUL-ZRH
Travel between 2 airports – round trip YUL-ZRH-YUL
Travel between 2 airports – one way (different departure point) YUL-ZRH,YYZ-ZRH
Travel between several one-way destinations YUL-ZRH-IST
Travel between several return destinations YUL-ZRH-IST-YUL
Travel between several destinations – multi-city YUL-ZRH,ZRH-IST,IST-YUL
Travel to several destinations from one airport YUL-MIA/MSY/DFW/EWR/YYZ/DEN
Travel between several destinations – multi-city from an airport YUL-ZRH-IST/BCN/CDG/TLV/CAI
Gcm Multi Segments

Draw radiuses from a destination

To draw radiuses on a map , you will have to use the arobase “@”, combined with a distance.

Here are the different actions possible with GCMAP:

Goal Example
Radius from an airport 1500mi@YUL
Multiple radiuses from an airport 500mi@YUL,1500mi@YUL,2750mi@YUL
Travel to several destinations from one airport YUL-YYZ/EWR/MSY/MIA/DFW/DEN/SFO

Once you have entered your radius(es), anything you enter in the search field will also display the radiuses on the map. It’s quite useful as part of the new Aeroplan program to quickly view direct flights and limits.

Gcm Distance Yul Map

Compare distances

To compare distances between different destinations (and to draw routes on a map), the hyphen “-” and the comma “,” should be used.

Here are the different actions possible with GCMAP:

Goal Example
Travel between 2 airports – one-way vs. connections (+10%) YUL-SIN,YUL-IST-SIN
Travel between 2 airports – one-way vs. connections (+60%) YUL-SIN,YUL-IST-JNB-SIN
Travel between 2 airports – one-way vs. connections (+122%) YUL-SIN,YUL-IST-JNB-AUH-ICN-SIN

Conclusion

You can do other things with GCMAP, like changing the path colours or the map format, but the parameters shown in this article are enough to get started with the tool!

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Jean-Maximilien Voisine
Jean-Maximilien Voisine
Jean-Maximilien, President and Founder of Milesopedia, is a recognized expert in rewards programs, credit cards, and travel in Canada and France. Approaching forty and a father of two, he has travelled to over 100 countries, half of them with his children and his wife, Audrey. Specializing in top loyalty programs like Aeroplan, American Express Membership Rewards, and Marriott Bonvoy, he guides travellers to maximize their benefits across North America and Europe.
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