Aqueduct supports different types of price functions. These can be used individually or combined to express more complex business models in a price model. You can create price models using the API or the Aqueduct dashboard.

Variables for a price function can either be fixed, or "allow dynamic values", which allows you to set new values at subscription creation time, along with minimum/maximum boundaries, instead of fixing the variable values at price model creation time.

Price function type


Billing calculation



unitCount: number
rate: number

total = unitCount * rate

This function supports prorations. A $30 a month plan that starts halfway through the month and is billed at the end of the month would be charged $15 the first month.

per-unit functions can be used to bill a monthly subscription at $10 per seat for 5 seats.

Variables for this example:

unitCount: 5
rate: $10.00
billingFrequency: monthly


amount: number | output of another price function

percent: number

total = amount * percent

This function can use a specified amount or the output for other pricing functions.

Percent functions can be used to represent a 50% discount on the first month

Variables for this example:

amount: Sum of all other price functions.
percent: 50


meter: string, refers to the event name that you're using for this meter

tiers: List of {
tierCutoff: number
rate: number

billable event associated with this meter are:

eventName: string
customerId: string
data: {
count: number

Sums the numbers of events that falls under each tier by that tier's rate.

For example:
90 events with tier
0-25 = $5

25 5 = 125 (for 0-25 events)
4 = 100 (for 26-50 events)
40 * 3 = 120 (for 51-90)

Total = $225 (from adding up all tiers 125 + 100 + 120)

Per unit meter is used to represent a service provider that charges $100 per hour and provided 20 hours of work.

Variables for this example:

meter: hourly_work_cody
tiers: {
rate: $100

eventName: hourly_work_code (the event name and meter name must match)
data: {
count: 20