The Data-Backed Answer: Keep It Short, But Know Where the Studies Disagree
The research is clear that shorter cold emails outperform longer ones — but the exact sweet spot depends on which dataset you trust, and it's worth understanding the difference before you blindly pick a number.
Hunter.io's analysis of 34 million cold emails found that emails between 20-39 words had the highest average reply rate at 4.5%. Emails under 100 words averaged 3.9% versus 3.7% for longer emails — directionally better, but the author's own takeaway is that the differences are modest and word count alone is not a silver bullet.
Overloop's data from 1.2 million sequences (note: Overloop is a cold email sequencing vendor with a commercial interest in this topic) shows 50-125 words as the sweet spot with an 8.2% reply rate, dropping to 3.9% at 200-300 words. Topo.io also recommends 50-125 words as the ideal range — but their recommendation is based on the Boomerang study (see below), not independent Topo research.
The widely cited Boomerang study of 40 million emails also found 50-125 words performed best. However, Hunter.io's own researcher explicitly flagged that Boomerang's dataset almost certainly included non-cold email communications, making its reported response rates unrealistically high for cold outreach benchmarking. Take those absolute figures with a grain of salt — the directional finding (shorter is better, 50-125 words is a reasonable target) still holds across multiple sources.
Where the Research Points in Different Directions
Here's the honest read: Hunter.io's data favors 20-39 words for the peak reply rate in pure cold email campaigns. Overloop and the Boomerang-derived consensus favor 50-125 words. These aren't the same recommendation. Hunter.io's author also notes the differences between word count buckets are not dramatic — a well-crafted 115-word email in their dataset achieved a 15% reply rate, while a 9-word email hit 13%.
The practical takeaway: aim for 50-125 words as a workable default range that gives you room to make a clear point and a low-friction ask. If you can say everything you need in 20-39 tight, personalized words, the data suggests that works even better — but most reps can't, and a sparse email that lacks context won't help either.
Why Short Emails Win
Busy prospects scan on mobile. A wall of text gets deleted before it's read. Eric Nowoslawski's cold email copywriting guidance, published on Clay.com, recommends keeping cold emails under 100 words with attention-grabbing copy that drives action — this is his personal guidance based on experience, not a controlled study, but it aligns with the broader data direction. The less friction you create, the more replies you'll get.
The goal isn't to hit a magic word count. It's to use the minimum number of words needed to make your prospect understand why they should reply. If you can do that in 30 words, great. If you need 100, use 100. Just don't pad it to feel more "professional."
Practical Guidelines
- First-touch cold emails: Target 50-125 words. Hunter.io's data suggests 20-39 words can peak even higher if your hook is razor-sharp and highly personalized.
- Follow-ups: Go shorter — under 50 words. They've already seen your first email; just add one new angle and a clear ask.
- Complex or technical sales: You can push toward 125-150 words if every word earns its place. Going over 200 words consistently hurts reply rates across multiple datasets.
- Subject lines: Aim for 4-7 words. Overloop's data shows this range gets the highest open rates.