---
title: Is Email Really Making You Money? How to Measure It Like a Finance Team.
description: "Klaviyo revenue isn't profit. Measure email marketing ROI like a finance team: check attribution windows, count discounts and split buyers from non-buyers."
image: https://splashdigital.co.nz/hubfs/Katherine%20-%20Image%201.png
---
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# Is Email Really Making You Money? How to Measure It Like a Finance Team.
*By Gavin Hewitson, founder of In-box.*
Most ecommerce brands judge email on one number: attributed revenue in Klaviyo. It's a useful number, but it isn't profit. It doesn't account for all the discounts you gave away, the margin on the products sold, or whether those customers would have bought anyway.
I run [In-box](https://in-box.com), a Klaviyo email marketing agency, and we've worked with more than 500 ecommerce brands. The brands that get the most out of email measure it as a finance team would. Here's how they do it:
### 1. Check the attribution window first
Klaviyo's default attribution window is 5 days. We regularly audit accounts where an agency has stretched it to 20 or 30 days, which credits email with sales it had little to do with. The revenue number looks great, but it tells you nothing.
Before you compare email with paid media or SEO, make sure the window is sensible, and the same logic applies to every channel. Otherwise, you're comparing numbers built on different rules.
### 2. Look at email's share, not just its total
Revenue increasing doesn't prove email is working, because the whole business might be growing. What's more relevant is whether email revenue is growing faster than the store's overall revenue.
[Scott Hawaii](https://in-box.com/case-studies/scott-hawaii), a Hawaiian footwear brand, is a good example. The business grew 42.3% year on year. Over that same period, email-attributed revenue grew 121.6%, and email reached 38% of attributed revenue in April.
Email revenue was growing nearly three times as fast as the business overall, so something was clearly working.
In the healthy accounts we manage, email and SMS often sit at around 30% of revenue. One eight-figure store we audited was at about 32%, or roughly $400,000 of $1.2 million a month.
### **[](https://in-box.com/case-studies/dermavenue)**
**Source: In-box client account (Dermavenue)**
### 3. Count the discounts as a cost
A campaign that drives $50,000 on a 30% code isn't the same as one that drives $50,000 at full price. Treat discounts as a cost of the channel, not a footnote.
[Michael Gabriels](https://in-box.com/case-studies/michael-gabriels), a lab-grown diamond jewellery brand, used to run 25% to 30% discount codes and saw margin squeezed at every peak. We switched to product-level price drops instead, and discount code usage fell 67%. Even so, Valentine's Day 2026 attributed sales rose 441%, and Black Friday Cyber Monday 2025 orders grew from 324 to 3,393.
### 4. Separate buyers from non-buyers
Across our accounts, roughly 80% of campaign revenue comes from people who have already bought. In the eight-figure account, one campaign made $7,262 from past buyers and $640 from non-buyers.
That split matters for margin. Repeat customers don't necessarily need a discount to buy again, so only non-buyers should see the welcome offer. If every campaign carries a code for everyone, you’re giving away margin on orders you would have received at full price.
### 5\. Stop paying to email people who don't open
Klaviyo bills by the number of profiles, and sending to people who never open hurts deliverability. To fix this, sunset contacts who haven't engaged in months, and send most of your campaigns to an engaged segment.
Our default engaged segment is anyone who has opened or clicked in the last 90 days, or been active on site or subscribed in the last 30 days, and hasn't bounced in the last 30 days.
An engaged audience can receive around 15 emails a month without any deliverability problems. Your full list should get closer to three.
### Where to start
You can start measuring email like a finance team would by checking your attribution window this week.
Then compare email's growth with the business's growth over the last year, add discounts to your email cost line, and split your next campaign into buyers and non-buyers.
If you'd like more examples, our [ecommerce email marketing case studies](https://in-box.com/case-studies) show the numbers behind each account. For quick changes you can make today, read [three Klaviyo tweaks that unlock hidden revenue](https://in-box.com/insights/three-email-marketing-tips-to-double-revenue), and our free Figma email template pack has layouts to build from.
\-----
About the author
Gavin Hewitson is the founder of In-box, a Klaviyo Master Gold Partner agency for ecommerce brands. Over five years, he and his team have worked with more than 500 ecommerce brands on email and SMS. See their results at [in-box.com/case-studies](https://in-box.com/case-studies), or download their [free Figma email template pack](https://in-box.com/free-email-templates).
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