How incremental is a promo code?

It depends entirely on distribution. A code emailed to lapsed customers is largely incremental; a public code that reaches coupon aggregators mostly is not.

Promo Code ROI Calculator

Most of the discount goes to people buying anyway.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Currency

Redemptions

Average order value with the code

Discount

Contribution margin

Share that is incremental

Cost of promoting the code

Incremental profit

$5,488

$15,219 on reported attribution

Revenue with the code$52,480

Discount given$7,872

Given to people buying anyway$4,723

Incremental profit$5,488

$4,723 of the discount went to customers who were buying regardless. Public codes leak to coupon sites and get used by everyone; codes tied to a specific audience leak less and are worth considerably more.

How the Promo Code ROI Calculator works

Public codes leak to coupon sites and get used by everyone, including customers who were already at checkout. Codes tied to a specific audience leak far less and are worth considerably more per pound of discount given.

Also known as: is my promo code profitable · discount code return · coupon campaign ROI

Measuring a code properly

Return on a promo code is incremental contribution divided by the discount given. Both terms are harder to establish than they look.

Incremental contribution means the contribution on orders that would not have happened otherwise. Attributed revenue on orders that used the code is not the same thing, and it is what most reporting shows.

The discount given is the easy part and it is not the only cost. Add the cost of running the campaign, the margin on any orders that would have been placed at full price, and any orders where the code was applied on top of an existing sale.

Attribution against incrementality

Attribution asks which orders used the code. Incrementality asks which orders happened because of it. They are different questions and only the second answers whether the campaign was worth running.

The gap between them is usually large. A code distributed by email to existing customers will be used by people who were already going to buy, and attribution credits every one of those orders to the campaign.

The only reliable way to separate them is a holdout: a randomly selected group that does not receive the code, whose purchase rate provides the baseline. It costs a small amount of forgone revenue and it is the difference between knowing and guessing.

Code hygiene

Unique codes per recipient prevent sharing and enable per-recipient measurement. They are more work to distribute and they close the largest leak.

Generic codes leak to voucher sites within hours of being issued at any scale, at which point the campaign is a public discount rather than a targeted one, and the measurement becomes meaningless as well as the economics.

Expiry dates, single-use enforcement, minimum spend and exclusion from sale items are the standard set of controls. Each is a checkout configuration and collectively they are the difference between a campaign that costs what was budgeted and one that does not.

The checkout coupon field

A visible coupon field at checkout prompts customers to go looking for a code, and a proportion of them find one and use it on a purchase they were making anyway.

The effect is measurable and it is negative in most tests. Customers leave the checkout to search, some do not come back, and those who do return with a discount.

The fixes range from removing the field entirely to hiding it behind a link to auto-applying codes from a URL so nobody needs to search. Each trades some friction for legitimate code holders against the leak, and the right balance depends on how much of your business genuinely runs on codes.

The programme view

Individual code performance matters less than the aggregate. A business running many codes should know what proportion of orders carry a discount and what the realised discount rate is across the year.

Those two numbers, tracked over time, show whether the promotional programme is expanding or being controlled. A rising proportion of discounted orders means the customer base is being trained to wait.

The corrective is usually structural rather than tactical: fewer codes, better targeted, with more of the value delivered through mechanisms that do not advertise a lower price. That is a harder programme to run and it does not degrade the price expectation in the way that a permanent stream of codes reliably does.

Where to go next

The Promo Code ROI question rarely arrives on its own. These are the ones that usually come with it:

Coupon Affiliate Attribution Calculator — They were already in the basket.
Coupon Value Calculator — The minimum spend does the work.
Stackable Discount Calculator — Stacking multiplies, which helps you.
Etsy Fee Calculator — Every Etsy fee on one sale, itemised.

Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price, check the platform's current fee schedule before you price a product against it. This is not tax or business advice.

Frequently asked questions

How do I stop codes leaking?

Unique single-use codes, codes tied to an account, and avoiding an obvious empty code field at checkout, that field prompts the search that starts the leakage.

Should I remove the code field?

If you rarely run codes, hiding it behind a link reduces the number of customers who leave to search for one and do not come back.

How do I measure incrementality?

Withhold the code from a matched group and compare conversion and revenue. It is the only way to separate the discount's effect from the traffic it happened to arrive with.