How does Great Circle Mapper – GCMap work?

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 |

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.

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!
Which credit card should you choose for travel?
If you travel regularly, the credit card you carry makes a real difference: travel insurance, points earning, airport lounge access and no foreign exchange fees. Use our credit card comparator to filter through 200+ Canadian cards based on your needs, or browse the best credit cards in Canada, ranked monthly by the Milesopedia team.
Other useful flight tools
- Skyscanner: compare prices on flights, hotels and rental cars
- Google Flights: find the best flights and fares quickly
- SeatGuru: choose the best seats on board (and its replacements)
- ExpertFlyer: check seat and business-class availability
GCMap – Frequently Asked Questions
Is Great Circle Mapper free?
Yes. Great Circle Mapper is completely free and requires no sign-up. You simply enter airport codes in the search bar to get distances and a map.
Why calculate a flight distance with GCMap?
Several loyalty programs, such as the British Airways Executive Club (Avios), price a flight in points based on the distance flown. Knowing the exact distance helps you spot the best point redemptions and the most advantageous stopovers.
What are the four characters to know on GCMap?
The dash (-) links destinations, the comma (,) separates queries, the slash (/) duplicates a query, and the at sign (@) draws a radius from an airport. These four characters cover most maps.
Does GCMap show the actual flight path?
GCMap draws the great-circle route, the shortest distance between two points on the globe. The actual flight path can vary slightly with air corridors, but the difference is minimal for estimating points.
Our featured card
Our editorial integrity
Our reviews and rankings are based on an objective assessment. Advertisers do not influence our content. We may receive compensation through some links; our analysis and opinions remain independent.



