IVF due date calculator template

Free build guide: IVF due date calculator for WordPress

This guide rebuilds the IVF due date calculator from this site in Gravity Forms: 2 inputs, 6 live results and no submit button. Expect about 24 minutes by hand. The template above is the same form as an import file, and the bundle adds a PDF version of this guide with a screenshot of every setting, plus the stylesheet.

You will end up with:

• Due date
• Weeks pregnant
• and days
• Days until the due date
• Trimester
• Due date, in days after transfer

What you need

• Gravity Forms (any license) — Calculation fields are in core; datediff(), floor() and the if-block need GP Advanced Calculations.
• GP Advanced Calculations (Gravity Wiz) — Exponents, functions and date math in calculation fields. The formulas in this template use its syntax. Part of Gravity Perks; needs the Spellbook plugin active as well.

The formulas below use GP Advanced Calculations syntax: exponents, functions or date math that core calculation fields cannot do. Install and activate it, with its Spellbook parent plugin, before you start; without it every result shows 0.

1. Create the form

1. Go to Forms → New Form and name it IVF due date.
2. In Form Settings → Form Layout, set the CSS Class Name to fo-live-only. Step 3 uses it to hide the submit button.
3. Leave the form open in the editor; the fields come next.

2. Add the fields, in this order

Field IDs are assigned as you add fields. If yours come out differently, change the {Label:ID} references in the formulas to match your IDs. Settings not mentioned stay at their defaults.

1. Transfer date · Date · ID 1
Date Input Type Date Picker; Date Format mm/dd/yyyy; Default Value {date_mdy}; Description “The day the embryo was transferred, fresh or frozen.”; Layout: half width, on the same row as its neighbor (drag the field beside it in the editor; no CSS class needed).

2. Embryo age at transfer · Radio Buttons · ID 2
Layout: half width, on the same row as its neighbor (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-segmented.

Choices (tick show values and enter each value):

• Day 3 — value 3
• Day 5 — value 5 (selected by default)
• Day 6 — value 6

3. Due date · Number · ID 8
Number Format 9,999.99; Description “Transfer date + 266 days − embryo age.”; Custom CSS Class (Appearance tab) fo-result fo-result--date; tick Enable Calculation, Rounding 0.

4 + datediff( "1970-01-05", {Transfer date:1} ) + 266 - {Embryo age:2}

4. Weeks pregnant · Number · ID 3
Number Format 9,999.99; Description “Gestational age, counted the way your doctor counts it.”; Layout: half width, on the same row as its neighbor (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

( ( ( datediff( "1970-01-05", today() ) - datediff( "1970-01-05", {Transfer date:1} ) ) + 14 + {Embryo age:2} ) - ( ( datediff( "1970-01-05", today() ) - datediff( "1970-01-05", {Transfer date:1} ) ) + 14 + {Embryo age:2} ) % 7 ) / 7

5. and days · Number · ID 4
Number Format 9,999.99; Layout: half width, on the same row as its neighbor (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

( ( datediff( "1970-01-05", today() ) - datediff( "1970-01-05", {Transfer date:1} ) ) + 14 + {Embryo age:2} ) % 7

6. Days until the due date · Number · ID 5
Number Format 9,999.99; Layout: half width, on the same row as its neighbor (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

280 - ( ( datediff( "1970-01-05", today() ) - datediff( "1970-01-05", {Transfer date:1} ) ) + 14 + {Embryo age:2} )

7. Trimester · Number · ID 6
Number Format 9,999.99; Description “First to week 13, second to week 27, third after.”; Layout: half width, on the same row as its neighbor (drag the field beside it in the editor; no CSS class needed); Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

if( ( ( datediff( "1970-01-05", today() ) - datediff( "1970-01-05", {Transfer date:1} ) ) + 14 + {Embryo age:2} ) < 91 ):
1
elseif( ( ( datediff( "1970-01-05", today() ) - datediff( "1970-01-05", {Transfer date:1} ) ) + 14 + {Embryo age:2} ) < 189 ):
2
else:
3
endif;

8. Due date, in days after transfer · Number · ID 7
Number Format 9,999.99; Description “Count this many days from your transfer date.”; Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 0.

266 - {Embryo age:2}

3. Hide the submit button

The results are live, so nothing needs submitting. Add this filter to your theme’s functions.php or a code-snippets plugin; it hides the button on any form carrying the fo-live-only class:

add_filter( 'gform_submit_button', function ( $button, $form ) {
	return str_contains( (string) rgar( $form, 'cssClass' ), 'fo-live-only' ) ? '' : $button;
}, 10, 2 );

Or with CSS alone: .fo-live-only_wrapper .gform_footer { display: none; }

4. Show the due date as a date

Calculation fields only hold numbers, so the Due date field calculates the number of days since January 1, 1970. A short script turns that number into a date such as “Friday, July 2, 2027” while the field keeps storing the number, so entries and merge tags still work.

1. Keep the Custom CSS Class fo-result fo-result--date on the field, as set in step 2.
2. Load the script on the page with the form: it comes in the template and bundle downloads as date-display.js. Paste it, inside <script> tags, into your site footer with a code-snippets plugin, or enqueue it from your theme after jQuery and Gravity Forms.
3. Preview the form: the result shows as a weekday and date, and a dash until a date is entered.

5. Put it on a page and make it look like this

Add the form to any page with the Gravity Forms block, or the shortcode [gravityform id="X" title="false" ajax="false"]. The form inherits your theme’s styles; the classes you set in step 2 are hooks for the look you see on this site:

• fo-result on a calculation field makes it the big teal result panel.
• fo-result fo-result--sub makes the smaller secondary figures.
• fo-segmented on a radio field turns it into a segmented switch.
• Two fields on one row is the editor’s own column layout: drag a field beside another and the row splits in half. No CSS class is needed, and the old gf_left_half Ready Classes are deprecated.

The bundle includes the two stylesheets that implement those classes, with notes on matching your brand colors. Without them the form still works; it just looks like your theme’s default Gravity Forms styling.

How the math works is explained under “How it’s calculated” on the live IVF due date calculator.