Heart-rate zones calculator template

Free build guide: Heart-rate zones calculator for WordPress

This guide rebuilds the Heart-rate zones calculator from this site in Gravity Forms: 3 inputs, 11 live results and no submit button. Expect about 42 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:

• Maximum heart rate (bpm)
• Zone 1 from (50%)
• Zone 1 to (60%)
• Zone 2 from (60%)
• Zone 2 to (70%)
• Zone 3 from (70%)
• Zone 3 to (80%)
• Zone 4 from (80%)
• Zone 4 to (90%)
• Zone 5 from (90%)
• Zone 5 to (100%)

What you need

• Gravity Forms (any license) — Calculation fields and radio values are in core.

Everything here is core Gravity Forms. No add-ons.

1. Create the form

1. Go to Forms → New Form and name it Heart-rate zones.
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. Age · Number · ID 1
Number Format 9,999.99; Default Value 40; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

2. Resting heart rate (bpm) · Number · ID 2
Number Format 9,999.99; Default Value 60; Description “Count it in bed before getting up, or read it off a watch. 60–70 is typical; fit people run lower.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

3. Method · Radio Buttons · ID 3
Custom CSS Class (Appearance tab) fo-segmented.

Choices (tick show values and enter each value):

• Heart-rate reserve (Karvonen) — value 1 (selected by default)
• Percent of maximum — value 0

4. Maximum heart rate (bpm) · Number · ID 4
Number Format 9,999.99; Description “220 minus age. A measured maximum from a hard test is better if you have one.”; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 0.

( 220 - {Age:1} )

5. Zone 1 from (50%) · Number · ID 5
Number Format 9,999.99; Description “Recovery, very easy.”; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.5 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.5 )

6. Zone 1 to (60%) · Number · ID 6
Number Format 9,999.99; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.6 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.6 )

7. Zone 2 from (60%) · Number · ID 7
Number Format 9,999.99; Description “Easy aerobic, conversational. Most of your training time.”; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.6 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.6 )

8. Zone 2 to (70%) · Number · ID 8
Number Format 9,999.99; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.7 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.7 )

9. Zone 3 from (70%) · Number · ID 9
Number Format 9,999.99; Description “Steady tempo, short sentences.”; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.7 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.7 )

10. Zone 3 to (80%) · Number · ID 10
Number Format 9,999.99; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.8 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.8 )

11. Zone 4 from (80%) · Number · ID 11
Number Format 9,999.99; Description “Threshold, hard, a few words at a time.”; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.8 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.8 )

12. Zone 4 to (90%) · Number · ID 12
Number Format 9,999.99; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.9 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.9 )

13. Zone 5 from (90%) · Number · ID 13
Number Format 9,999.99; Description “Maximal, intervals of a few minutes at most.”; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 0.9 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 0.9 )

14. Zone 5 to (100%) · Number · ID 14
Number Format 9,999.99; Layout: half width, on the same row as its neighbour (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.

( {Method:3} * ( {Resting:2} + ( ( 220 - {Age:1} ) - {Resting:2} ) * 1 ) + ( 1 - {Method:3} ) * ( 220 - {Age:1} ) * 1 )

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. 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 colours. Without them the form still works; it just looks like your theme’s default Gravity Forms styling.

How the maths works is explained under “How it’s calculated” on the live Heart-rate zones calculator.