# How do you use custom fields with the ~Contact.FirstName~ functions?

**URL:** <https://integration.keap.com/t/how-do-you-use-custom-fields-with-the-contact-firstname-functions/91635>\
**Category:** Max Classic\
**Tags:** campaign-builder, custom-fields, api\
**Created:** [October 17, 2023, 8:53pm UTC](https://integration.keap.com/t/how-do-you-use-custom-fields-with-the-contact-firstname-functions/91635 "2023-10-17T20:53:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Matthew\_Wertz](https://avatars.discourse-cdn.com/v4/letter/m/71c47a/32.png) [@Matthew\_Wertz](https://integration.keap.com/u/Matthew_Wertz)\
**Post date:** [October 17, 2023, 8:53pm UTC](https://integration.keap.com/t/how-do-you-use-custom-fields-with-the-contact-firstname-functions/91635/1 "2023-10-17T20:53:11Z")

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How do you use the ~Contact.FirstName~ format on custom fields? For example if my Custom Field is “Model Number” I’ve tried ~Contact.ModelNumber~, but to no avail, it does not work.

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**Author:** ![Jeff\_Arnold](https://sea1.discourse-cdn.com/flex019/user_avatar/integration.keap.com/jeff_arnold/32/14802_2.png) [@Jeff\_Arnold](https://integration.keap.com/u/Jeff_Arnold)\
**Post date:** [October 17, 2023, 9:27pm UTC](https://integration.keap.com/t/how-do-you-use-custom-fields-with-the-contact-firstname-functions/91635/2 "2023-10-17T21:27:47Z")

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You need to insert an underscore after the period.

~Contact.\_ModelNumber~

Assuming ‘ModelNumber’ is the correct database name.

If you go into an email and choose the ‘merge’ option, you can insert the merge code and check it exactly.

Thanks,  
Jeff