Add gender to Klaviyo profiles
Klaviyo stores custom profile properties without any setup. Let a Zap or a Make scenario write gender and gender_probability to each new profile, then segment on both.
100 free credits every day. No card.
Two custom properties, no setup
Klaviyo creates a custom property the first time a value is written to it, so there is nothing to configure in advance. Use gender for the label and gender_probability for the number.
Build segments on both: Properties about someone, gender equals female and gender_probability is at least 90. A segment on the label alone also catches every weak guess.
Flows that change wording or product picks by gender should have a neutral branch for profiles where gender is not set. Those are the profiles NameGender could not answer, usually role addresses or initials.
Zapier: New Profile → Find Gender → Update Profile
Add NameGender to your Zapier account with the invitation link on this page. Trigger: Klaviyo, New Profile, or Profile added to Segment or List when only one list matters. Action: NameGender, Find Gender, with First Name as the name; set the type of value to Email and map Email when first names are often missing. Action: Klaviyo, Update Profile, with the profile from the trigger and two custom properties, gender and gender_probability.
Map the Country field when your sign-up form or store collects it. Klaviyo stores country as a full name in some setups; NameGender expects a two-letter ISO code such as US or DE, so check the value before mapping it.
A three-step Zap needs a paid Zapier plan. In Make: Klaviyo’s new-profile trigger, NameGender’s Get Gender from a Name, then Klaviyo’s update-profile module.
Backfill existing profiles
Export a list or segment with email, first name and country, upload it in the NameGender dashboard and start the job after checking the cost. Import the result back as a list upload with the two columns mapped to gender and gender_probability; Klaviyo matches on email and updates the existing profiles.
Questions
Do I need to create the properties first?
No. Klaviyo creates a custom property when the first value is written.
Which input is better, first name or email?
First name when you have it. Email works when the address contains the name and is useful for sign-up forms without a name field.
Can I send the country as “Germany”?
Send the two-letter code, DE. A full country name is not accepted.
Does an unknown name cost a credit?
Yes. Every lookup costs one credit, including unknown names and role addresses.
Related pages
Fill a GENDER audience field for new Mailchimp subscribers from the first name or email, then segment and personalise only where the answer is confident.
Add gender and probability to Stripe customer metadata from the customer name or email, with a webhook handler or a Zapier flow into your CRM or sheet.
Detect gender from an email address. The exact local-part transform, how role addresses and initials are handled, and the pre-filter that saves credits.
Reading the gender field alone discards everything that says whether to believe it. What each response field means and the thresholds behind confidence.
Check it against your own list
Every number on this page is reproducible with a free key. If your data breaks it, that is the more interesting result.