Coincidence factor formula
Coincidence factor = coincident system maximum demand ÷ sum of individual maximum demands.
Because the coincident system peak represents one simultaneous system condition, it is compared with the arithmetic sum of the separate group maxima. The resulting factor is generally between 0 and 1 when the inputs are defined consistently.
What the number tells you
A higher coincidence factor means a larger fraction of the separate group peak total is present at the system peak. A lower factor indicates more temporal separation between group peaks.
Worked example
If the individual maximum demands sum to 115 units and the system's coincident maximum is 80 units, the coincidence factor is 80 ÷ 115 = 0.6957, or about 69.6%.
Peak relationship
The tool also calculates the difference between the sum of individual peaks and the coincident system peak. This is the non-coincident portion within this arithmetic comparison. It should not be interpreted as permanently unavailable capacity.
Data quality matters
All values need compatible definitions and time periods. A group maximum obtained over one sampling basis cannot automatically be compared with a system maximum from an unrelated period without understanding the measurement methodology.
Safety and limitations
This metric is a planning and analytical relationship. It does not provide an equipment rating, breaker setting or code-compliance conclusion.
Frequently asked questions
Is coincidence factor just the inverse of diversity factor?
When both are calculated from the same group peaks and coincident system peak, yes: one is the reciprocal of the other.
Can coincidence factor be over 1?
Not under consistent definitions where the coincident peak cannot exceed the sum of the relevant individual maximum demands.
Does a higher coincidence factor mean the system is inefficient?
No. Coincidence factor describes timing overlap, not electrical efficiency.