Methodology: Email Marketing ROI Calculator

1. Scope

Projects revenue, ROI, and cost-per-acquisition for an email campaign from list size, open rate, click-through rate, conversion rate, and average order value. It does not model list decay, deliverability, or spam-folder effects.

2. Inputs and outputs

Inputs

listSize number
openRate percent
clickThroughRate percent
conversionRate percent
averageOrderValue number (currency)
campaignCost number (currency)

Outputs

clicks

listSize × openRate × clickThroughRate.
conversions

clicks × conversionRate.
revenue

conversions × averageOrderValue.
roi

(revenue − campaignCost) / campaignCost.
costPerAcquisition

campaignCost / conversions.

Engine source: src/lib/email-marketing-roi-calculator/engine.ts

3. Formula / scoring logic

opens       = list_size * open_rate
clicks      = opens * ctr
conversions = clicks * cvr
revenue     = conversions * aov
roi         = (revenue - campaign_cost) / campaign_cost

4. Assumptions

Every opened email is uniquely opened by a human. Apple Mail Privacy Protection (2021+) inflates reported open rates.
Deliverability is 100%. Spam/quarantine-folder losses are out of scope.
CTR and CVR are independent of list segment — no segmentation uplift.

5. Data sources

CAN-SPAM Act compliance guidance, US FTC as of 2023

6. Known limitations

Open-rate figures have been unreliable since Apple MPP (iOS 15, 2021). Use click-through as the primary engagement metric.
Vendor-reported email ROI figures ("$42 per $1 spent") are self-reported and we do not cite them.

7. Reproducibility

Input
list = 10,000, open = 25%, ctr = 3%, cvr = 2%, aov = $50, cost = $200.

Expected output
clicks = 75, conversions ≈ 2, revenue ≈ $75, roi ≈ -62.5% (negative at this conversion rate).

8. Change log

2026-04-24 methodology page first published.