Purchase Frequency
Purchase frequency is the average number of orders placed per customer over a specified period.
What is Purchase Frequency?
The metric describes order repetition in the customer population being measured. Its unit is orders per customer per period, not a percentage. It can help explain why revenue changes even when the number of buyers and average basket value stay similar.
Two common populations give different answers: customers who bought during the period, or an original cohort that includes customers with no later orders. State which denominator is used before comparing the result.
Purchase frequency = Eligible orders ÷ Customers in the defined population
For a period-buyer version, divide by unique purchasing customers in that period. For a cohort version, keep the original cohort denominator, including zero-order customers in later intervals.
Two orders per quarterly customer
A stationery store records 1,800 orders from 900 unique purchasing customers in a quarter. Purchase frequency is two orders per purchasing customer per quarter. This average could include many one-time buyers and a smaller group ordering frequently; it does not mean every customer placed exactly two orders.
How to interpret it
Frequency describes depth of ordering, whereas repeat purchase rate describes the proportion of customers who repeated. A few highly active buyers can raise frequency without many more customers becoming repeat buyers.
For matching populations and revenue definitions, average order value multiplied by purchase frequency equals revenue per customer for the period. This is an arithmetic relationship, not evidence that increasing order count will necessarily increase contribution.
Frequent small orders may create more shipping, packaging and payment costs than fewer larger baskets. Assess the economics of the order pattern rather than assuming the highest frequency produces the best customer value.
Product replenishment cycles and seasonality influence the observation. A quarterly figure should not be compared directly with an annual one, and multiplying a holiday-quarter rate by four may overstate normal annual behavior.
Common mistakes
Using only repeat buyers in an all-customer metric
That excludes the one-order customers and overstates frequency for the complete purchasing population.
Treating frequency as time between orders
Orders per customer and days between purchases are related but different measures. Their averages are not generally interchangeable.