Startup Co- founders Share

Normally new startup teams equally divide business share among co-founders. According to this philosophy, if co-founders are three then they feel justice in dividing share 33.3% each. But this is not as simple in many cases where co-founders have differences in their contributions, expertise and responsibilities.
So the following factors and their weights are important while dividing shares among co-founders.

Startup Idea
Domain Expertise
Business Expertise (Business Plan Preparation etc.)
Responsibilities accountable
Commitment and Risk

First, co-founders have to set ‘weight’ of each factor with consensus and then give ‘points’ against each factors to each co-founder.