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.
Provincial population ÷ electoral quotient = initial provincial seat allocation
Application of the "senatorial clause" and "grandfather clause"
Application of the "representation rule"
Total provincial seats + one seat per territory = total number of seats
1 – Initial allocation of seats to the provinces
The total population of each province is from Statistics Canada's quarterly estimate of July 1, 2021. The electoral quotient is obtained by multiplying the quotient of the last decennial redistribution (111,166) by the average of the population growth rates of the 10 provinces (9.647%) in the last 10 years. The new electoral quotient thus calculated is 121,891. The number of seats initially allocated to each province is calculated by dividing the population number of each province by the electoral quotient. This figure is then rounded up to the next whole number.
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.