Fixed Per Product
An incentive structure that pays a flat fee per unit of a product sold. Multiplies by quantity.
Requires Siren Essentials
Last updated: April 9, 2026
Fixed Per Product is an incentive structure that pays a flat fee for each unit of a qualifying product sold. Unlike Fixed Per Transaction, which pays once per conversion, this structure multiplies the flat fee by the quantity of units in the transaction.
When a customer converts, Siren counts qualifying units across the transaction’s line items and creates an obligation for the unit count times the configured per-unit amount. Line item filters determine which products count.
How it works
If the incentive is set to $5 per unit and a customer buys 8 units of a qualifying product in a single order, the commission is $40. If they buy 1 unit, it’s $5. Quantity drives the payout.
This structure is a good fit when unit profit is roughly constant. If each product unit yields the same margin, a flat per-unit commission gives you predictable cost-per-sale math. You can calculate exactly what a collaborator earns for any cart composition without worrying about fluctuating percentages.
Where this works
This works best for stores with uniform product pricing and stable per-unit margins (books, standardized supplements, consumer electronics with fixed retail prices). It also suits subscription services with flat monthly pricing, where you can easily compute a sustainable per-signup payout based on average customer lifetime value.
The fixed rate affiliate program recipe uses a flat dollar payout per sale, which works well whenever the business math on each unit is predictable enough to set a sustainable commission up front.
When to avoid this
If you sell products at wildly different price points and want affiliates to focus on higher-value items, use Percentage of Transaction instead. A flat per-unit fee treats a $10 product and a $500 product the same, which usually doesn’t match your actual margin on either.
It’s also not a fit for service businesses or programs where the thing being sold isn’t a discrete product unit. If you’re paying for subscriptions, leads, or single-transaction outcomes without a per-unit concept, Fixed Per Transaction or Percentage of Transaction will fit better.