Frequency is the number of times something happens within a particular period.
Cumulative means increasing or growing by accumulation or successive additions.
Cumulative frequency is the total of a frequency and all frequencies so far in a frequency distribution.
How to calculate cumulative frequency.
The frequency distribution table below records number of plates with their colours.
| Colour of plate | Number (Frequency) |
| Red | 12 |
| Blue | 8 |
| Violet | 15 |
| Indigo | 20 |
The first cumulative frequency is the same as the first frequency, as you just add a zero to the frequency.
To calculate cumulative frequency, we add the first frequency to the second frequency, then add the third frequency to the result and the process continues.
| Colour of plate | Number (frequency) | Cumulative frequency |
| Red | 12 | 12 |
| Blue | 8 | 20 |
| Violet | 15 | 35 |
| Indigo | 20 | 55 |
The cumulative frequency in the last row is the same as the total sum of frequencies.
