60-amp is a genuine problem in a modern household. 100-amp is workable for many homes and constraining for others.
The service size is how much electricity the house can draw at once. It was set when the home was built, for the demands of that era — and household demand has risen enormously since.
Breakers tripping regularly, lights dimming when a large appliance starts, a panel that is visibly full with no spare slots, or a proliferation of tandem breakers doubled into single spaces. An inspector will identify the size; you can often read it from the main breaker.
Upgrading a service is not a small job — it involves the panel, often the mast and meter base, permits and an inspection, and sometimes utility coordination. Cost varies considerably with the house and how the supply arrives, so get an electrician's quote on the actual property rather than relying on a general figure.
If you are buying an older Calgary home and intend to add air conditioning or an EV charger, price the electrical upgrade before you write the offer. It is a predictable cost that buyers routinely discover a year later.
Related era issues: aluminum wiring and what to inspect by decade.