BMI Calculator in GF

In gravity form

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### ✅ **Step-by-step Implementation**

#### 1. **Create Fields in Gravity Forms**

1. **Weight Unit Selector (Radio or Drop-down)**
– Label: `Select Weight Unit`
– Type: Drop-down
– Choices:
– Kilograms (kg)
– Stones & Pounds

2. **Weight Input Fields**
– **Weight in kg**
– Label: `Weight (kg)`
– Type: Number
– Enable Conditional Logic: Show **if Weight Unit is Kilograms**

– **Weight in stones**
– Label: `Weight (stones)`
– Type: Number
– Enable Conditional Logic: Show **if Weight Unit is Stones & Pounds**

– **Weight in pounds**
– Label: `Weight (pounds)`
– Type: Number
– Enable Conditional Logic: Show **if Weight Unit is Stones & Pounds**

3. **Height Unit Selector**
– Label: `Select Height Unit`
– Type: Drop-down
– Choices:
– Centimeters (cm)
– Feet & Inches

4. **Height Input Fields**
– **Height in cm**
– Label: `Height (cm)`
– Type: Number
– Enable Conditional Logic: Show **if Height Unit is Centimeters**

– **Height in feet**
– Label: `Height (feet)`
– Type: Number
– Enable Conditional Logic: Show **if Height Unit is Feet & Inches**

– **Height in inches**
– Label: `Height (inches)`
– Type: Number
– Enable Conditional Logic: Show **if Height Unit is Feet & Inches**

5. **BMI Output Field**
– Label: `Your BMI`
– Type: Calculation
– Use merge tags and logic below (we’ll customize this next).

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### 🧮 **BMI Calculation Logic**

Since BMI = weight (kg) / (height in meters)^2
We need to convert:

– **Stones + pounds → kg**
`(stones * 6.35029) + (pounds * 0.453592)`

– **Feet + inches → meters**
`((feet * 12) + inches) * 0.0254`

– **cm → meters**
`cm / 100`

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### 🧠 **Smart Calculation using Gravity Forms Calculation Field**

Use conditional merge tags in the **BMI Calculation field** with Gravity Forms’ conditional logic.

Example formula (pseudo-logic; actual logic will depend on field IDs):

IF Weight Unit = "Kilograms" AND Height Unit = "Centimeters":
  BMI = {Weight_kg:1} / (({Height_cm:2} / 100)^2)

IF Weight Unit = "Stones & Pounds" AND Height Unit = "Feet & Inches":
  BMI = (({Weight_stone:3} * 6.35029) + ({Weight_pound:4} * 0.453592)) / (((( {Height_feet:5} * 12 ) + {Height_inch:6}) * 0.0254)^2)

➡ You can break these into multiple **hidden number fields**:
– One for `weightInKg`
– One for `heightInM`
– Final **BMI field** can then do:
`weightInKg / (heightInM^2)`

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### 💡 Tips

– Use **Gravity Perks GP Conditional Logic Dates** plugin if you need more advanced conditional calculations.
– Label fields clearly so users know which units they are entering.
– Add description texts like "Enter only numbers".

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### ✅ Example Field Mapping (assuming field IDs):

| Field | Field ID |
|——-|———-|
| Weight Unit | `1` |
| Weight (kg) | `2` |
| Weight (stones) | `3` |
| Weight (pounds) | `4` |
| Height Unit | `5` |
| Height (cm) | `6` |
| Height (feet) | `7` |
| Height (inches) | `8` |
| Hidden Weight in kg | `9` |
| Hidden Height in meters | `10` |
| BMI Output | `11` |

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Would you like me to generate **custom JavaScript** that auto-converts the fields in Gravity Forms instead of using hidden calculated fields?

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### ✅ Step 1: Add Fields to Gravity Form

#### **1. Weight Unit Selector**
– Type: Drop-down
– Label: `Select Weight Unit`
– Choices:
– Kilograms (value: kg)
– Stones & Pounds (value: stlb)
– **Field ID: `1`**

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#### **2. Weight Inputs**
– **Weight (kg)**
– Type: Number
– ID: `2`
– Conditional Logic: Show if **Field 1 = Kilograms**

– **Weight (stones)**
– Type: Number
– ID: `3`
– Conditional Logic: Show if **Field 1 = Stones & Pounds**

– **Weight (pounds)**
– Type: Number
– ID: `4`
– Conditional Logic: Show if **Field 1 = Stones & Pounds**

—

#### **3. Height Unit Selector**
– Type: Drop-down
– Label: `Select Height Unit`
– Choices:
– Centimeters (value: cm)
– Feet & Inches (value: ftin)
– **Field ID: `5`**

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#### **4. Height Inputs**
– **Height (cm)**
– Type: Number
– ID: `6`
– Conditional Logic: Show if **Field 5 = Centimeters**

– **Height (feet)**
– Type: Number
– ID: `7`
– Conditional Logic: Show if **Field 5 = Feet & Inches**

– **Height (inches)**
– Type: Number
– ID: `8`
– Conditional Logic: Show if **Field 5 = Feet & Inches**

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### ✅ Step 2: Add Calculation Fields (Hidden)

#### **5. Weight in kg (hidden)**
– Type: Number
– ID: `9`
– Visibility: Hidden
– Calculation Logic:

if({1} = "kg", {2}, ({3} * 6.35029) + ({4} * 0.453592))

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#### **6. Height in meters (hidden)**
– Type: Number
– ID: `10`
– Visibility: Hidden
– Calculation Logic:

if({5} = "cm", {6} / 100, (({7} * 12) + {8}) * 0.0254)

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### ✅ Step 3: Final BMI Calculation Field

#### **7. Your BMI**
– Type: Number
– ID: `11`
– Label: `Your BMI`
– **Calculation Formula**:

{9} / ({10} * {10})

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### ✅ Optional Styling / Descriptions

– Add descriptions to fields like:
– “Enter weight in kilograms”
– “Enter height in centimeters”
– “Stones and pounds will be converted automatically”
– You may want to **round BMI** using JavaScript or CSS for cleaner output.

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### ✅ Done!

Your Gravity Form now:
– Accepts weight and height in **different unit systems**
– Converts them automatically in the background
– Shows accurate **BMI** with proper logic

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Would you like a **ready-to-import Gravity Forms JSON** file for this setup?

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### 🔢 Example 1: **Weight in Kilograms**, Height in **Centimeters**

– **Weight**: 70 kg
– **Height**: 175 cm

**Convert height to meters**:
175 ÷ 100 = **1.75 m**

**BMI formula**:
70 ÷ (1.75 × 1.75) = **22.86**

✅ **BMI = 22.86**

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### 🔢 Example 2: **Weight in Stones and Pounds**, Height in **Feet and Inches**

– **Weight**: 11 stones 0 pounds
– **Height**: 5 feet 9 inches

**Convert weight to kg**:
(11 × 6.35029) + (0 × 0.453592) = **69.85 kg**

**Convert height to meters**:
(5 × 12 + 9) = 69 inches
69 × 0.0254 = **1.7526 m**

**BMI formula**:
69.85 ÷ (1.7526 × 1.7526) = **22.73**

✅ **BMI = 22.73**

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### 🔢 Example 3: **Weight in Stones and Pounds**, Height in **Centimeters**

– **Weight**: 10 stones 5 pounds
– **Height**: 160 cm

**Convert weight to kg**:
(10 × 6.35029) + (5 × 0.453592) = 63.50 + 2.27 = **65.77 kg**

**Convert height to meters**:
160 ÷ 100 = **1.60 m**

**BMI formula**:
65.77 ÷ (1.60 × 1.60) = **25.70**

✅ **BMI = 25.70**

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Let me know if you’d like the same examples implemented in a real **Gravity Forms live calculator** or need a downloadable form file.

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### ✅ Updated Plan for Stones and Pounds with "st" and "lg" Options

#### 1. **Weight Unit Selector**
– **Field Type**: Drop-down
– **Label**: *Select Weight Unit*
– **Choices**:
– Kilograms (value: `kg`)
– Stones and Pounds (value: `stlb`) ✅

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#### 2. **Weight Input for Stones (st)**
– **Field Type**: Number
– **Label**: *Weight (st)*
– **Field ID**: `3`
– **Show if** Weight Unit = `stlb`

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#### 3. **Weight Input for Pounds (lg)**
– **Field Type**: Number
– **Label**: *Weight (lg)* or *Pounds (lb)*
– **Field ID**: `4`
– **Show if** Weight Unit = `stlb`

You can add a small description like:
> "Enter additional pounds (e.g., 5 if weight is 10 st 5 lb)"

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### 🧠 Conversion Formula Example

Let’s say the user enters:
– **10 st**
– **6 lg (pounds)**

#### Convert to kg:

(10 * 6.35029) + (6 * 0.453592) = 63.50 + 2.72 = 66.22 kg

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### ✅ Gravity Forms Calculation Field (Hidden)

Create a **hidden field** to calculate **Weight in kg**:

if({1} = "kg", {2}, ({3} * 6.35029) + ({4} * 0.453592))

Where:
– `{1}` = Unit selector
– `{2}` = Direct kg input
– `{3}` = Stones
– `{4}` = Pounds (lg)

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### ✅ Sample Inputs and Result

| Stones (st) | Pounds (lg) | Resulting Weight (kg) |
|————-|————-|————————|
| 12 | 0 | 76.20 kg |
| 10 | 4 | 65.27 kg |
| 8 | 10 | 56.25 kg |

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Would you like me to export this setup as a Gravity Forms **.json file** ready to import into your site?

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### ✅ Goal
When **“Stones and Pounds”** is selected in the **Weight Unit** dropdown, show:
– 🪨 One input field labeled **“Stones (st)”**
– ⚖️ One input field labeled **“Pounds (lb or lg)”**

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### ✅ Gravity Forms Setup

#### 🔹 **Step 1: Weight Unit Selector**
– **Field Type**: Drop-down
– **Label**: `Select Weight Unit`
– **Choices**:
– Kilograms (value: `kg`)
– Stones and Pounds (value: `stlb`)
– **Field ID**: `1`

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#### 🔹 **Step 2: Weight Input for Kilograms**
– **Field Type**: Number
– **Label**: `Weight (kg)`
– **Field ID**: `2`
– **Conditional Logic**: Show if Field `1` is `kg`

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#### 🔹 **Step 3: Weight Input for Stones (st)**
– **Field Type**: Number
– **Label**: `Weight (Stones)`
– **Field ID**: `3`
– **Conditional Logic**: Show if Field `1` is `stlb`

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#### 🔹 **Step 4: Weight Input for Pounds (lg)**
– **Field Type**: Number
– **Label**: `Additional Pounds`
– **Field ID**: `4`
– **Conditional Logic**: Show if Field `1` is `stlb`

💡 *Add description below the field:*
> Example: If your weight is 10 st 6 lb, enter 10 and 6.

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#### 🔹 **Step 5: Hidden Field to Convert to KG**
– **Field Type**: Number (Hidden)
– **Label**: `Weight in KG (calculated)`
– **Field ID**: `9`
– **Formula**:

if({1} = "kg", {2}, ({3} * 6.35029) + ({4} * 0.453592))

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### ✅ Sample Output

If user selects “Stones and Pounds” and enters:

– Stones (st): `10`
– Pounds (lg): `5`

The calculated weight will be:

(10 * 6.35029) + (5 * 0.453592) = 63.5029 + 2.26796 = **65.77 kg**

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Let me know if you want:
– This full setup exported as a **Gravity Forms JSON file**, or
– A similar logic for height (feet/inches) with meters conversion.