Unit converter template

Free build guide: Unit converter for WordPress

This guide rebuilds the Unit converter from this site in Gravity Forms: 12 inputs, 9 live results and no submit button. Expect about 63 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:

• Result
• Result
• Result
• Fahrenheit (°F)
• Kelvin (K)
• Celsius (°C)
• Kelvin (K)
• Celsius (°C)
• Fahrenheit (°F)

What you need

• Gravity Forms (any license) — Calculation fields, drop-down values and conditional logic 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 Unit converter.
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. Convert · Radio Buttons · ID 1
Custom CSS Class (Appearance tab) fo-segmented.

Choices (tick show values and enter each value):

• Length — value length (selected by default)
• Weight — value weight
• Volume — value volume
• Temp — value temp

2. Amount · Number · ID 2
Number Format 9,999.99; Default Value 10; Conditional Logic (Advanced tab): Show this field if Convert is Length..

3. From · Drop Down · ID 3
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Length..

Choices (tick show values and enter each value):

• Millimetres (mm) — value 0.001
• Centimetres (cm) — value 0.01
• Metres (m) — value 1
• Kilometres (km) — value 1000
• Inches (in) — value 0.0254
• Feet (ft) — value 0.3048 (selected by default)
• Yards (yd) — value 0.9144
• Miles (mi) — value 1609.344

4. To · Drop Down · ID 4
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Length..

Choices (tick show values and enter each value):

• Millimetres (mm) — value 0.001
• Centimetres (cm) — value 0.01
• Metres (m) — value 1 (selected by default)
• Kilometres (km) — value 1000
• Inches (in) — value 0.0254
• Feet (ft) — value 0.3048
• Yards (yd) — value 0.9144
• Miles (mi) — value 1609.344

5. Result · Number · ID 5
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 4; Conditional Logic (Advanced tab): Show this field if Convert is Length..

{Amount:2} * {From:3} / {To:4}

6. Amount · Number · ID 6
Number Format 9,999.99; Default Value 150; Conditional Logic (Advanced tab): Show this field if Convert is Weight..

7. From · Drop Down · ID 7
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Weight..

Choices (tick show values and enter each value):

• Milligrams (mg) — value 0.001
• Grams (g) — value 1
• Kilograms (kg) — value 1000
• Metric tons (t) — value 1000000
• Ounces (oz) — value 28.349523125
• Pounds (lb) — value 453.59237 (selected by default)
• Stone (st) — value 6350.29318

8. To · Drop Down · ID 8
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Weight..

Choices (tick show values and enter each value):

• Milligrams (mg) — value 0.001
• Grams (g) — value 1
• Kilograms (kg) — value 1000 (selected by default)
• Metric tons (t) — value 1000000
• Ounces (oz) — value 28.349523125
• Pounds (lb) — value 453.59237
• Stone (st) — value 6350.29318

9. Result · Number · ID 9
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 4; Conditional Logic (Advanced tab): Show this field if Convert is Weight..

{Amount:6} * {From:7} / {To:8}

10. Amount · Number · ID 10
Number Format 9,999.99; Default Value 1; Conditional Logic (Advanced tab): Show this field if Convert is Volume..

11. From · Drop Down · ID 11
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Volume..

Choices (tick show values and enter each value):

• Millilitres (ml) — value 1
• Litres (l) — value 1000
• Teaspoons (tsp) — value 4.92892159375
• Tablespoons (tbsp) — value 14.7867647813
• Fluid ounces (fl oz) — value 29.5735295625
• Cups — value 236.5882365
• Pints (pt) — value 473.176473
• Quarts (qt) — value 946.352946
• Gallons (gal) — value 3785.411784 (selected by default)
• Cubic feet (cu ft) — value 28316.846592

12. To · Drop Down · ID 12
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Volume..

Choices (tick show values and enter each value):

• Millilitres (ml) — value 1
• Litres (l) — value 1000 (selected by default)
• Teaspoons (tsp) — value 4.92892159375
• Tablespoons (tbsp) — value 14.7867647813
• Fluid ounces (fl oz) — value 29.5735295625
• Cups — value 236.5882365
• Pints (pt) — value 473.176473
• Quarts (qt) — value 946.352946
• Gallons (gal) — value 3785.411784
• Cubic feet (cu ft) — value 28316.846592

13. Result · Number · ID 13
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 4; Conditional Logic (Advanced tab): Show this field if Convert is Volume..

{Amount:10} * {From:11} / {To:12}

14. Temperature · Number · ID 14
Number Format 9,999.99; Default Value 72; Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Temp..

15. From · Drop Down · ID 15
Layout: half width, on the same row as its neighbour (drag the field beside it in the editor; no CSS class needed); Conditional Logic (Advanced tab): Show this field if Convert is Temp..

Choices (tick show values and enter each value):

• Celsius (°C) — value c
• Fahrenheit (°F) — value f (selected by default)
• Kelvin (K) — value k

16. Fahrenheit (°F) · Number · ID 16
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 2; Conditional Logic (Advanced tab): Show this field if Convert is Temp and From is Celsius (°C)..

{Temperature:14} * 9 / 5 + 32

17. Kelvin (K) · Number · ID 17
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 2; Conditional Logic (Advanced tab): Show this field if Convert is Temp and From is Celsius (°C)..

{Temperature:14} + 273.15

18. Celsius (°C) · Number · ID 18
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 2; Conditional Logic (Advanced tab): Show this field if Convert is Temp and From is Fahrenheit (°F)..

( {Temperature:14} - 32 ) * 5 / 9

19. Kelvin (K) · Number · ID 19
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 2; Conditional Logic (Advanced tab): Show this field if Convert is Temp and From is Fahrenheit (°F)..

( {Temperature:14} - 32 ) * 5 / 9 + 273.15

20. Celsius (°C) · Number · ID 20
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result; tick Enable Calculation, Rounding 2; Conditional Logic (Advanced tab): Show this field if Convert is Temp and From is Kelvin (K)..

{Temperature:14} - 273.15

21. Fahrenheit (°F) · Number · ID 21
Number Format 9,999.99; Custom CSS Class (Appearance tab) fo-result fo-result--sub; tick Enable Calculation, Rounding 2; Conditional Logic (Advanced tab): Show this field if Convert is Temp and From is Kelvin (K)..

( {Temperature:14} - 273.15 ) * 9 / 5 + 32

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 Unit converter.