The representation formula
Below is the formula for allocating seats in the House of Commons following each decennial (10-year) census. This representation formula is found in section 51 of the Constitution Act, 1867.
1 – Initial allocation of seats to the provinces
The population of a province is divided by the "electoral quotient" to provide the initial allocation of seats to that province. For the redistribution process following the 2011 census, the electoral quotient was set at 111,166. The electoral quotient for the redistribution process following the 2021 census will be adjusted to reflect average provincial population growth since the previous redistribution.
2 – Application of the special clauses
After the initial number of seats per province is obtained, adjustments are made to account for the "senatorial clause" and the "grandfather clause."
The senatorial clause guarantees that no province has fewer seats in the House of Commons than it has in the Senate. The grandfather clause guarantees each province no fewer seats than it had in 1985.
3 – Application of the "representation rule"
The "representation rule" will only apply to a province whose population was overrepresented in the House of Commons at the completion of the last redistribution process. As per this rule, if such a province would now be under-represented based on the calculations above, it will be given extra seats so that its share of House of Commons seats is proportional to its share of the population.
4 – Calculation of House of Commons seats
Once the special clauses and representation rule are applied, the number of seats for each province has been determined. Three seats are then allocated to the territories—one for each of the Yukon, the Northwest Territories and Nunavut—to obtain the total number of House of Commons seats.