Most Shopify merchants send the same emails to everyone on their list: campaigns, promotions, product launches. These are important. But they treat all subscribers identically, which means none of them feel particularly relevant.

Birthday campaigns are the opposite of this. They are personal, timely, and expected. And the data behind them is extraordinary: birthday emails achieve a 481 percent higher transaction rate than standard promotional emails, according to Experian's email benchmark report. That is not a small improvement. That is a fundamentally different level of performance.

The reason is simple: a birthday email arrives when the recipient is already in a buying mindset. They may be planning a treat for themselves, their friends and family are looking for gift ideas, and a personalised offer from a brand they have previously bought from fits perfectly into that context.

The challenge for most Shopify merchants is not the strategy. It is the mechanics: how do you collect birthdates at scale without friction, how do you set up the Klaviyo flow correctly, and how do you stay compliant with GDPR while doing it?

This guide covers all three.

How Do You Collect Birthdates Without Friction?

The biggest obstacle to running birthday campaigns is the data problem. You cannot send a birthday email if you do not know when your customers' birthdays are, and most merchants have not collected this data at scale.

The key principle is this: collecting a birthdate needs to feel like a benefit to the customer, not a request for personal data for your benefit. Framed correctly, it is a completely natural exchange.

Post-purchase popup The highest-converting method for most merchants. After a customer completes a purchase, a popup appears: "Tell us your birthday and we'll send you a special treat." Include a brief incentive description (for example, "a gift just for you"). Response rates of 20 to 40 percent are typical for well-designed post-purchase popups.

You do not need to tell customers what the offer is in advance. The element of surprise often improves engagement with the birthday email itself.

Account creation incentive Include a birthdate field in your Shopify customer account creation form. Either make it optional (most customers will skip it unless incentivised) or offer a specific incentive: "Add your birthday to unlock a surprise reward." This works well for brands with a loyalty programme or repeat-purchase model.

Tools like Yotpo Loyalty, LoyaltyLion, and Smile.io all support birthdate collection as part of account profile completion.

Welcome flow request In your welcome email series (triggered when a customer first subscribes), include a simple link: "Tell us your birthday for a special surprise." This can be a preference page link in Klaviyo that allows subscribers to update their own profile with a birthdate.

What not to do: adding a mandatory birthdate field to your checkout. This creates friction at the highest-value moment in the customer journey. Any modest gain in birthdate collection is not worth the conversion rate cost.

How Do You Set Up a Klaviyo Birthday Flow?

Klaviyo is the email platform most Shopify merchants use, with plans starting from approximately £20/month at typical mid-size list volumes. Its birthday flow feature is built in but requires correct configuration.

Step 1: Store the birthdate correctly Birthdates need to be stored as a profile property in Klaviyo. When you collect a birthdate via a popup tool (like Klaviyo's own forms, Privy, or OptiMonk), configure it to map to the Klaviyo birthday field. This is the $birthday property in Klaviyo's system.

If you collect birthdates via a form on your Shopify store, ensure the data syncs to Klaviyo via the Shopify-Klaviyo integration or a Zapier/Make workflow.

Step 2: Create the flow In Klaviyo, go to Flows, then Create Flow, then select "Birthday" from the pre-built flow templates. The trigger is set to fire based on the $birthday profile property.

You can configure when the flow triggers relative to the birthday: 7 days before (recommended for "your birthday is coming" teaser email), on the birthday itself (main offer email), and 7 days after (last chance email for customers who have not redeemed).

Step 3: Build the email sequence

Email	Timing	Purpose
Birthday teaser	7 days before	"Your birthday is coming - something special is waiting"
Birthday offer	Birthday date	Main offer email, personalised with first name
Reminder / last chance	7 days after (if not redeemed)	"Your birthday treat expires soon"

The main birthday email should feel personal and celebratory, not like a standard promotional email. Use the customer's first name, keep the design warm and specific to the occasion, and make the offer prominent and easy to redeem.

Step 4: Generate the discount code Klaviyo supports dynamic unique discount codes for birthday flows. Go to the email design, insert a dynamic block, and select "Unique Coupon" from the options. Set the discount parameters (percentage off, fixed amount off, or free shipping) and Klaviyo will generate a unique code for each recipient. This prevents code sharing.

Configure the code to expire 30 days from issue to create genuine urgency without the 7-day window feeling too short for a customer who was travelling on their birthday.

What Offer Should You Use?

The right birthday offer depends on your average order value and product margins. Three common structures:

Offer Type	When to Use	Example
Percentage discount	AOV above £30, healthy margins	"20% off your next order"
Fixed amount off	High AOV stores, cleaner copy	"£15 off your next order"
Free gift	Supplement, beauty, food merchants	"A free [product] with your next order"
Free shipping	High-volume, lower AOV	"Free express delivery on your birthday order"

A percentage discount is the most commonly used and simplest to configure. 15 to 20 percent is a typical birthday offer. Higher than this (30 to 40 percent) signals desperation rather than generosity.

A free gift works exceptionally well for consumables and replenishment products. It gives the customer a sample of a product they may not have tried and drives a full purchase alongside it. The perceived value is often higher than an equivalent cash discount.

Free express shipping as a birthday offer works well for merchants where delivery cost is a friction point (heavy products, premium delivery brands), but it typically underperforms compared to a discount on high-margin products.

How Do You Measure Birthday Campaign Performance?

Set up a custom report in Klaviyo for your birthday flow specifically. The key metrics:

Open rate: should be significantly higher than your average campaign open rate. 50 to 70 percent open rates for birthday emails are common on engaged lists.
Redemption rate: the percentage of recipients who use their birthday code. Aim for 10 to 20 percent. Below 5 percent suggests the offer is not compelling or the email design is poor.
Revenue per recipient: total revenue from the flow divided by number of recipients. Compare this to your typical campaign revenue per recipient. The benchmark gap (birthday emails at 481 percent higher transaction rate) gives you a target.
Average order value of birthday orders: do birthday buyers spend more or less than average? A well-designed birthday offer often drives higher AOV because customers treat themselves.

Review these metrics monthly and adjust the offer, timing, or email design if redemption rates are below expectations.

GDPR Considerations for Collecting Birthdates

Under GDPR, birthdates are personal data. You need a lawful basis for collecting and processing them.

For birthday campaigns, the lawful basis is typically legitimate interest (you have a legitimate interest in personalising marketing to existing customers) or consent (the customer actively opts in by submitting their birthdate in exchange for a birthday reward).

Practical requirements:

Your privacy policy must mention that you collect and use birthdates for personalised marketing.
The collection form or popup must make clear how the data will be used: "We'll send you a birthday reward by email."
Customers must be able to remove their birthdate from their profile on request (this is handled through Klaviyo's preference centre and Shopify's customer account deletion tools).
Do not share birthdate data with third parties unless you have explicit consent and this is declared in your privacy policy.

You do not need to collect the full date of birth. Month and day (without year) is sufficient for birthday campaigns and collects less sensitive data, which is good practice under GDPR's data minimisation principle.

Key Actions to Take Now

Set up a post-purchase popup in Klaviyo or Privy this week asking customers to share their birthday month and day in exchange for a surprise reward.
Build the Klaviyo birthday flow using the pre-built template: configure three emails (7 days before, birthday day, 7 days after) with dynamic unique discount codes.
Decide your offer type based on your AOV and margins. For most Shopify merchants, 15 to 20 percent off is the simplest and best-performing option.
Update your privacy policy to mention birthdate collection and its use for personalised marketing before you start collecting.
Set up a Klaviyo report for your birthday flow and review it monthly.
In your welcome email series, add a link asking new subscribers to share their birthday for a future reward. This compounds your birthdate collection rate over time.
After 60 days of the flow running, compare your birthday email redemption revenue against the cost of the offer to confirm positive ROI.

Frequently Asked Questions

How much higher do birthday emails perform compared to standard promotional emails? Experian's email benchmark data shows birthday emails achieve a 481 percent higher transaction rate than standard promotional emails. Open rates for birthday emails on engaged lists typically run at 50 to 70 percent, compared to 20 to 30 percent for standard campaigns.

How do I collect birthday data in Klaviyo for Shopify? Use Klaviyo's own embedded form builder, or a third-party popup tool like Privy or OptiMonk, to collect a birthdate field that maps to Klaviyo's $birthday profile property. Place the form as a post-purchase popup for the highest response rate. Include it as an optional field in account creation with an incentive.

Is it GDPR compliant to collect customer birthdates for birthday campaigns? Yes, with proper disclosure. You need a lawful basis (legitimate interest or consent), your privacy policy must mention birthdate collection and its use, and customers must be able to remove their data on request. Collecting month and day only (without year) reduces the sensitivity of the data and follows GDPR's data minimisation principle.

What is a good birthday discount offer for a Shopify store? 15 to 20 percent off the next order is the most commonly used and generally best-performing structure for merchants with an AOV above £30. A free gift works well for consumables and replenishment products. Free shipping as a birthday offer tends to underperform relative to a direct discount unless shipping cost is a significant friction point for your customer base.

Shopify Birthday Discount Campaigns: How to Set Them Up and Make Them Worth Running