Ampersand Breaking UTM Tracking: Fix & Symbol in Parameter Values
& in UTM campaign name truncating all parameters after it? Encode ampersand as %26 to preserve full campaign tracking in GA4.
Your campaign name is "save & win" but GA4 only shows "save". Everything after the & is missing.
Unencoded ampersands break parameter parsing. Here's the 60-second fix.
Table of contents
- The Problem
- Why It Happens
- Real Example
- The Fix
- Option 1: Encode as %26
- Option 2: Replace with "and"
- Option 3: Remove Ampersand
- Quick Encoding Script
- How Browsers Parse Ampersands
- Detection Script
- Testing After Fix
- Step 1: Check URL Structure
- Step 2: Test in Browser
- Step 3: Verify in GA4
- Common Ampersand Scenarios
- Scenario 1: Company Name with &
- Scenario 2: Product Names
- Scenario 3: Promotional Copy
- Platform-Specific Handling
- Google Ads
- Facebook Ads
- Email Platforms
- Prevention Checklist
- FAQ
- Why does & break URLs?
- Should I always encode & to %26?
- What if my platform auto-encodes?
- Can I use & in the base URL?
- Conclusion
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The Problem
❌ BROKEN:
?utm_campaign=save&win
Browser parses as:
utm_campaign = "save"
win = "" (new parameter with no value)
GA4 receives: campaign = "save"
Missing: "& win"
The & symbol is a reserved URL character. It separates parameters.
When you use & in a parameter value without encoding, the browser thinks you're starting a new parameter.
Why It Happens
Ampersand (&) is the parameter separator in URLs:
✅ CORRECT USAGE (separating parameters):
?utm_source=facebook&utm_medium=cpc&utm_campaign=spring
↑ ↑
Parameter separators
But when & appears INSIDE a value:
❌ WRONG (& in value, not encoded):
?utm_campaign=save&win&utm_medium=cpc
↑ ↑
Intended as part of campaign name
Parsed as parameter separator
Result:
- utm_campaign = "save"
- win = ""
- utm_medium = "cpc"
Real Example
Company: E-commerce retailer
Campaign: "Buy 1 & Get 1 Free" promotion
Budget: $25,000 Facebook ads
URL: ?utm_campaign=buy1&get1free
Result in GA4:
- Campaign name: "buy1"
- Everything after & lost
Impact:
- Could not identify "Buy 1 & Get 1" campaign in reports
- Data split: some sessions showed "buy1", some showed nothing
- $25,000 spend with truncated attribution
- Could not measure actual promo performance
Encoding the & would have preserved full tracking.
😰 Is this your only tracking issue?
This is just 1 of 40+ ways UTM tracking breaks. Most marketing teams have 8-12 critical issues they don't know about.
• 94% of sites have UTM errors
• Average: $8,400/month in wasted ad spend
• Fix time: 15 minutes with our report
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✓ Shows exact sessions affected
The Fix
Option 1: Encode as %26
❌ BEFORE:
?utm_campaign=save&win
✅ AFTER:
?utm_campaign=save%26win
GA4 shows: "save&win" (decoded automatically)
Option 2: Replace with "and"
❌ BEFORE:
?utm_campaign=save&win
✅ AFTER:
?utm_campaign=save-and-win
GA4 shows: "save-and-win"
Option 3: Remove Ampersand
❌ BEFORE:
?utm_campaign=buy1&get1
✅ AFTER:
?utm_campaign=buy1get1
GA4 shows: "buy1get1"
Quick Encoding Script
function encodeUtmValue(value) {
// Encode all special characters including &
return encodeURIComponent(value);
}
// Usage
const campaign = "save & win";
const encoded = encodeUtmValue(campaign);
console.log(encoded);
// Output: save%20%26%20win
// ↑ ↑
// space ampersand
// Build full URL
const url = `https://site.com?utm_campaign=${"{"}{"{"}encoded{"}"}{"}"}}`;
console.log(url);
// https://site.com?utm_campaign=save%20%26%20win
// GA4 receives: "save & win" (automatically decoded)How Browsers Parse Ampersands
Example URL:
https://site.com?utm_campaign=save&win&utm_medium=cpc
Browser interpretation:
Parameter 1: utm_campaign = "save"
Parameter 2: win = "" (no value provided)
Parameter 3: utm_medium = "cpc"
URLSearchParams output:
utm_campaign: "save"
win: ""
utm_medium: "cpc"
GA4 receives:
Campaign: "save"
Medium: "cpc"
(Everything between & symbols is lost or misinterpreted)
Detection Script
function detectUnencodedAmpersand(url) {
const params = new URL(url).searchParams;
const issues = [];
params.forEach((value, key) => {
// Check if value contains unencoded &
// (encoded & appears as %26 in raw query string)
const rawQuery = url.split('?')[1] || '';
const paramPattern = new RegExp(`${"{"}{"{"}key{"}"}{"}"}}=([^&]*)`);
const match = rawQuery.match(paramPattern);
if (match) {
const rawValue = match[1];
// If raw value contains & but not %26, it's unencoded
if (rawValue.includes('&') && !rawValue.includes('%26')) {
issues.push({
parameter: key,
value: value,
problem: 'Contains unencoded ampersand',
fix: `Encode as ${encodeURIComponent(value)}`
});
}
}
});
return issues;
}
// Usage
const url = 'site.com?utm_campaign=save&win';
console.log(detectUnencodedAmpersand(url));
// [{ parameter: 'utm_campaign', value: 'save', problem: 'Contains unencoded ampersand', ... }]Testing After Fix
Step 1: Check URL Structure
✅ CORRECT:
https://site.com?utm_campaign=save%26win&utm_medium=cpc
↑ ↑
Encoded &
Each %26 in URL = one & in the final value
Step 2: Test in Browser
1. Visit URL: https://site.com?utm_campaign=save%26win
2. Open browser console
3. Run: new URL(location.href).searchParams.get('utm_campaign')
4. Should output: "save&win" (decoded)
Step 3: Verify in GA4
1. Visit corrected URL
2. Open GA4 → Realtime
3. Check "Traffic acquisition"
4. Campaign should show complete value: "save&win"
Common Ampersand Scenarios
Scenario 1: Company Name with &
❌ WRONG:
utm_source=johnson&johnson
✅ RIGHT:
utm_source=johnson%26johnson
GA4 shows: "johnson&johnson"
Scenario 2: Product Names
❌ WRONG:
utm_content=shoes&boots
✅ RIGHT:
utm_content=shoes%26boots
GA4 shows: "shoes&boots"
Scenario 3: Promotional Copy
❌ WRONG:
utm_campaign=save-big&act-fast
✅ RIGHT:
utm_campaign=save-big%26act-fast
GA4 shows: "save-big&act-fast"
Platform-Specific Handling
Google Ads
Value Tracking Template:
`{"{"}{"{"}lpurl{"}"}{"}"}}`?utm_campaign=buy1%26get1free&gclid=`{"{"}{"{"}gclid{"}"}{"}"}}`
↑
Pre-encoded & in campaign name
Facebook Ads
URL Parameters field:
utm_source=facebook&utm_campaign=spring%26summer
↑
Encoded &
Email Platforms
<!-- Pre-encode in template -->
<a href="https://site.com?utm_campaign=save%26win&utm_source=email">
Click Here
</a>
<!-- Platform's click tracking preserves %26 -->Prevention Checklist
Before launching campaigns:
✅ Scan all UTM values for & symbols
✅ Replace with:
- %26 (encoded, preserves &)
- "and" (readable alternative)
- Remove (if not needed)
✅ Use encodeURIComponent() for automation
✅ Test URL in browser console
✅ Verify in GA4 Real-Time
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FAQ
Why does & break URLs?
& is reserved as the parameter separator. Using it in values without encoding confuses URL parsers.
Should I always encode & to %26?
Yes, if you want the & to appear in GA4. Alternative: replace with "and" or remove.
What if my platform auto-encodes?
Test it. Some platforms encode, some don't. Always verify the final URL received by users.
Can I use & in the base URL?
Yes. & is only problematic when used INSIDE parameter values. Between parameters, & is correct.
✅ CORRECT:
?param1=value1¶m2=value2
↑
& separating parameters (correct)
❌ WRONG:
?param1=value&value
↑
& inside value (must encode as %26)
Conclusion
Unencoded & in UTM values breaks parameter parsing. Fix: Encode as %26.
❌ utm_campaign=save&win
✅ utm_campaign=save%26win
✅ utm_campaign=save-and-win
Use encodeURIComponent() to automatically encode all special characters including &.
Technical Reference: Ampersand Not Encoded Validation Rule