It’s impossible to get a reply to an email that’s never opened.
You can spend all the time researching the prospect. Writing the perfect email.
But it’s all a waste if your subject line sucks.
To put this into perspective: top reps get 2.1x the opens compared to avg. reps:
The secret? They spend less time crafting the perfect subject line. And they throw all marketing gimmicks out the window.
We analyzed 85M+ cold emails to figure out exactly how these top reps achieve 58%+ open rates on their cold emails:
- How Long Should Your Cold Email Subject Lines Be?
- What Language Should You Use? Avoid?
- How Does Capitalization Affect Open Rates?
- What Subject Line Formulas Perform The Best?
Hang around until the end. You’ll get my top four subject line formulas (with email examples) for driving 50%+ open rates.
I’ll also draw from my firsthand experience at Outbound Squad training reps at companies like Gong, Zoom, Shopify, and Rippling.
Let’s dig in.
How Long Should Your Cold Email Subject Lines Be?
Leverage what our friend Will Allred calls “internal camouflage.” Mirror your buyer’s internal communication style:
- ❌ Long & Salesy: Reducing Outbound Squad’s Hiring Time.
- ✅ Straight to the point: new sales trainer hire
Keep it short and don’t get fancy.
Gong data shows that the shorter the subject line, the higher the open rate:
1-4 words is the ideal range.
You might be tempted to use an empty subject line. Gong data shows that you’ll increase open rates by 30%, but you’ll tank reply rates by 12%.
Stop it with the gimmicks.
What Language Should You Use? Avoid?
Don't give your prospect a reason to delete the email before they even open it.
That means no selling. No fancy hooks or Buzzfeed-style headlines. And please, please do not talk about AI.
Gong data shows that salesy techniques reduce open rates by as much as 17.9%:
Stick to priority-based language that speaks to the prospect’s world:
- Priorities. Specific initiatives your buyers care about. Either stated publicly or what their peers are generally focused on.
- Current Solutions & Problems. How your buyer is making progress on those priorities. Their tools, people, process, and the associated problems.
- Aspirations. Outcomes they hope to achieve. Their desired future state.
Check out these examples:
Resist talking about your solution in the subject line. Your open rate will thank you.
How Does Capitalization Affect Open Rates?
I’ve always trained reps to use lower case subject lines. Now we have data to back it up.
Gong data shows that all lowercase subject lines have the highest open rates:
Don’t capitalize any letters in your subject line. The only exception is for proper nouns.
What Subject Line Formulas Perform The Best?
I pulled together our four best performing subject line formulas with examples below.
1. Pervasive Problems
2. Industry Trends
3. 1-2 word pattern interrupts
4. Competitor Share
Verdict: Keep Subject Lines Simple And Short
I would even venture to say “boring.” Don’t get fancy.
You’ll double open rates by sticking to the basics:
- Under 4 words
- No pitching
- All lowercase
Want more? The Ultimate Cold Email Data Report breaks down 20+ data-backed email insights that separate the top reps from the pack.
