A negative consumption value occurs when your stock levels have increased despite taking all intakes into consideration.

This tends to happen due to one of two possible causes:

1. Intake not processed at the correct date/time
2. Miscounted bottles

In either case, there should never be any negative consumption values.

## Calculation

Your consumption between two inventory sessions is calculated as follows:

Consumption = Total Bottles (Beginning) + Bottles Received - Total Bottles (End)

#### Example

1. Let's say for a given week, you start off with 7 bottles, receive 6 bottles, then end up with 9 bottles the next time you take inventory. We can compare the outcomes if we process the intake incorrectly:

Correct: 7 (beginning) + 6 (received) - 9 (ending) = 4 bottles consumed

Bad Intake: 7 (beginning) + 0 (received) - 9 (ending) = -2 bottles consumed

1. The same problem can arise with miscounts. Let's say you have a bottle that has not been used at all, with 5 in stock. We can compare the outcomes if we forget 2 bottles during the first inventory:

Correct: 5 (beginning) + 0 (received) - 5 (ending) = 0 bottles consumed

Miscount: 3 (beginning) + 0 (received) - 5 (ending) = -2 bottles consumed