Paint calculator template

Free build guide: Paint calculator for WordPress

This guide rebuilds the Paint calculator from this site in Gravity Forms: 7 inputs, 3 live results and no submit button. Expect about 30 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:

• Gallons for the walls
• Wall area to paint (sq ft)
• Gallons for the ceiling

What you need

• Gravity Forms (any license) — Calculation fields 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 Paint.
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. Room length (ft) · Number · ID 1
Number Format 9,999.99; Default Value 12; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

2. Room width (ft) · Number · ID 2
Number Format 9,999.99; Default Value 10; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

3. Wall height (ft) · Number · ID 3
Number Format 9,999.99; Default Value 9; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

4. Coats · Number · ID 4
Number Format 9,999.99; Default Value 2; Range min 1 max 5; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

5. Doors · Number · ID 5
Number Format 9,999.99; Default Value 1; Description “About 20 sq ft each.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

6. Windows · Number · ID 6
Number Format 9,999.99; Default Value 2; Description “About 15 sq ft each.”; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed).

7. Coverage per gallon (sq ft) · Number · ID 7
Number Format 9,999.99; Default Value 350; Description “Printed on the can. 350–400 is typical; porous or dark walls cover less.”.

8. Gallons for the walls · Number · ID 8
Number Format 9,999.99; Description “Round up to whole gallons. Four quarts make a gallon.”; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 2.

( 2 * ( {Length:1} + {Width:2} ) * {Wall height:3} - {Doors:5} * 20 - {Windows:6} * 15 ) * {Coats:4} / {Coverage:7}

9. Wall area to paint (sq ft) · Number · ID 9
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.

( 2 * ( {Length:1} + {Width:2} ) * {Wall height:3} - {Doors:5} * 20 - {Windows:6} * 15 )

10. Gallons for the ceiling · 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 1.

{Length:1} * {Width:2} * {Coats:4} / {Coverage:7}

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 Paint calculator.