Klaviyo Custom Properties: Track Anything, Segment Everything

One of the most powerful features in Klaviyo is one that most brands never touch.

Custom properties let you attach any data point you want to a customer profile. Not just the default stuff Klaviyo pulls from Shopify (email, name, order history, location) — literally anything. Skin type. Flavor preference. Dog breed. Shirt size. When they last called customer support. How they answered a quiz. Their subscription tier.

Once that data lives on the profile, you can use it to segment your list, personalize emails, trigger flows, and build marketing so targeted it feels like you're reading the customer's mind.

And yet, 90% of the Klaviyo accounts I audit have zero custom properties configured. They are using Klaviyo like a basic email tool when it is capable of being a marketing intelligence platform.

Let me show you what custom properties are, how to set them up, and the specific use cases that generate the most revenue.

What Custom Properties Actually Are

Every profile in Klaviyo has properties. Some are default — $email, $first_name, $city, $source. These come from your Shopify integration or signup forms automatically.

Custom properties are additional data fields you create and populate. They can hold any information:

• Text: "skin_type" = "oily"
• Number: "loyalty_points" = 450
• Boolean: "is_vip" = true
• Date: "birthday" = "1990-05-15"
• List: "preferred_categories" = ["skincare", "supplements"]

Once a custom property exists on a profile, you can use it everywhere in Klaviyo:

• Segmentation: Create a segment of all customers where "skin_type" equals "oily"
• Flow triggers: Start a flow when "loyalty_points" exceeds 1,000
• Conditional content: Show different product recommendations in the same email based on "preferred_categories"
• Personalization: "Hey Sarah, time to restock your favorite oily skin moisturizer"

How to Create and Populate Custom Properties

There are four main ways to get custom property data into Klaviyo:

Method 1: Signup Forms and Popups

The simplest way. Add a question to your signup form and map the answer to a custom property.

Example: Your popup says "What are you most interested in?" with options: Skincare, Supplements, Fitness. The answer maps to a custom property called interest_category on the profile.

In Klaviyo's form builder: Add a radio button or dropdown field. Under "Map to profile property," enter your custom property name. When someone submits the form, the answer is automatically added to their profile.

Method 2: Quiz or Survey Data

Product recommendation quizzes are one of the best sources of custom property data. A quiz asks the customer questions about their needs and preferences, recommends products, and stores all that preference data on their Klaviyo profile.

Tools that integrate with Klaviyo: Octane AI, Typeform, Digioh, and others can push quiz responses directly to Klaviyo as custom properties.

Example quiz flow: "What's your skin concern?" maps to skin_concern. "How old are you?" maps to age_range. "What products do you currently use?" maps to current_routine. Now you have a profile enriched with data that lets you send incredibly targeted emails.

Method 3: Shopify Data via Integration

Your Shopify store contains data that doesn't sync to Klaviyo by default but can be pushed through with custom integration work.

Examples:

• Subscription status (active, paused, cancelled)
• Customer tags from Shopify (VIP, wholesale, employee)
• Product-specific data (size purchased, color preference based on order history)
• Discount code usage history

How to push it: Use Klaviyo's API, a Shopify Flow automation, or a middleware tool like Zapier to sync Shopify data to Klaviyo custom properties. For example, a Shopify Flow that triggers when a customer is tagged "VIP" and sets the Klaviyo custom property customer_tier to "VIP."

Method 4: Manual or CSV Upload

For one-time data imports or data from offline sources, you can upload a CSV with custom property columns.

Example: You ran an in-person event and collected attendee emails with their product interests. Upload a CSV with columns: email, event_attended = "Brand Summit 2026", interest = "premium skincare."

Go to Klaviyo, then Lists/Segments, then Import. Map your CSV columns to custom properties. The data populates on matching profiles.

The Custom Properties That Drive the Most Revenue

Not all custom properties are equally useful. Here are the ones that consistently generate the most segmentation and personalization value:

1. Product Category Preference

Property name: preferred_category How to populate: Quiz data, purchase history analysis, signup form selection

How to use it:

Segment your list by preferred category. Send skincare-focused campaigns to the skincare segment. Send supplement campaigns to the supplement segment. Instead of sending every campaign to your entire list and hoping for relevance, each subscriber gets content tailored to what they actually care about.

Revenue impact: Category-segmented campaigns typically see 40-60% higher click rates and 2-3x higher revenue per recipient compared to unsegmented blasts.

2. Customer Lifecycle Stage

Property name: lifecycle_stage Values: prospect, first_purchaser, repeat_customer, vip, at_risk, lapsed

How to populate: Automated calculation based on purchase history. Update via Shopify Flow or Klaviyo's computed properties.

How to use it:

Different lifecycle stages get different messaging. Prospects get education and social proof. First purchasers get onboarding and cross-sell. VIPs get early access and exclusive offers. At-risk customers get re-engagement. Lapsed customers get win-back with incentives.

Revenue impact: Lifecycle-segmented flows outperform generic flows by 3-5x in revenue per recipient.

3. Birthday

Property name: birthday or birth_month How to populate: Signup form field, quiz question, or post-purchase survey

How to use it:

Birthday emails are one of the highest-converting automated emails in eCommerce. A simple "Happy birthday! Here's a gift from us" with a special offer generates massive goodwill and purchases.

Revenue impact: Birthday emails average $0.50-$2.00 RPR. With a list of 50,000 profiles that have birthday data, that is $25K-$100K annually from one automated flow.

4. Size or Fit Data

Property name: shirt_size, shoe_size, fit_preference How to populate: Purchase history, quiz, or explicit preference collection

How to use it:

Only recommend products available in their size. Include size in restock notifications ("Your size M in the Classic Tee is back in stock"). Personalize product recommendation emails to show items in their size.

Revenue impact: Reducing "item not available in my size" disappointment increases click-to-purchase rates by 15-25%.

5. Subscription Status

Property name: subscription_status Values: active, paused, cancelled, never_subscribed

How to populate: Sync from your subscription platform (Recharge, Skio, Bold) to Klaviyo

How to use it:

Active subscribers get different emails than non-subscribers. Paused subscribers get re-activation flows. Cancelled subscribers get targeted win-back with subscription-specific offers. Non-subscribers get education about the subscription value proposition.

6. Customer Support Interaction

Property name: last_support_ticket, support_sentiment How to populate: Integration with your helpdesk (Gorgias, Zendesk) or manual tagging

How to use it:

If a customer had a negative support experience in the last 7 days, suppress them from promotional emails. Nobody wants a "buy more!" email while they are waiting for a refund.

Conversely, if a customer had a positive support resolution, follow up with a review request — they are feeling good about the brand.

Building Segments With Custom Properties

Here are specific, high-value segments you can build once you have custom properties:

High-value prospects: Subscribers who took a quiz, expressed interest in premium products, but haven't purchased yet. Send them targeted product recommendations with social proof from similar customers.

Repeat buyers in a specific category: Customers who have purchased 3+ times from the supplements category. Send them new supplement launches, bundle offers, and subscription pitches.

VIP birthday month: VIP customers whose birthday is this month. Send an extra-special birthday offer with a higher-value gift or discount than standard customers receive.

Lapsed subscribers by preference: Customers who haven't purchased in 90+ days, segmented by their preferred category. Send category-specific win-back with new products in their interest area.

Size-matched new arrivals: Customers whose preferred size matches in-stock inventory for a new product launch. "New arrival in your size — shop before it sells out."

Conditional Content With Custom Properties

This is where it gets really powerful. Instead of creating separate emails for each segment, you can use conditional content blocks within a single email to show different content to different people.

Example: A weekly newsletter that shows:

• Skincare product recommendations to subscribers where preferred_category equals "skincare"
• Supplement recommendations to subscribers where preferred_category equals "supplements"
• Bestsellers to subscribers where preferred_category is empty

Same email template. Same send time. Three different experiences. This saves you from creating and managing dozens of separate campaigns while still delivering personalized content.

In Klaviyo's email builder, you add a conditional content block, set the condition to a profile property, and define what shows for each value.

Maintenance and Data Hygiene

Custom properties are only useful if the data is accurate and current. Here are the maintenance practices:

Audit properties quarterly. Review which custom properties exist and whether they are actively used in segments, flows, or content. Remove unused properties to keep profiles clean.

Set up automated updates. Properties like lifecycle_stage and subscription_status should update automatically based on behavior, not require manual updates.

Handle conflicting data. If a customer's quiz says they prefer skincare but their last 3 purchases were all supplements, which do you trust? Build logic that prioritizes recent purchase behavior over stated preferences, with the stated preference as a tiebreaker.

Validate on input. When collecting data through forms, use validation to prevent garbage data. Dropdown menus and radio buttons are better than open text fields for properties you plan to segment by.

Custom properties transform Klaviyo from a broadcast email tool into a precision marketing platform. The setup takes a few hours. The segmentation and personalization opportunities are permanent.

If your Klaviyo profiles are bare-bones and you want to unlock the full power of custom properties, we build these systems for eCommerce brands every month.

Book a call and let's enrich your Klaviyo data for smarter marketing.