Speed-to-lead beats follow-up sequences every time.

The classic study is the 2007 InsideSales / MIT / Kellogg / Harvard Business Review paper on lead response times, often referenced as the "Lead Response Management Study." It tracked thousands of web leads across hundreds of B2B companies and found two specific effects. First, vendors who contacted leads within 5 minutes were 9x more likely to qualify them than vendors who waited 30 minutes. Second, in head-to-head bids, the first vendor to reach the buyer won the business roughly 78% of the time. The decay curve in this calculator interpolates between the published anchor points (1 min, 5 min, 30 min, 1 hr, 24 hr) and adds a +30% ceiling for the sub-1-minute case based on more recent telephony research and Nirvani deploy data.

Nothing about the human attention span ends at 5 minutes. The number is a published empirical finding, not a theory. The decay starts the instant a lead hits "submit," because that's the moment they are most actively comparing vendors. Most buyers form a strong vendor preference within the first 5 to 15 minutes of evaluation. After that, they start fielding follow-up calls from competitors who heard about them via paid-intent data. The 5-minute cliff is the curve flattening into the territory where the lead has already started a parallel conversation with someone else.

We interpolate logarithmically between published anchor points: 1 min = 1.30x, 5 min = 1.00x, 30 min = 0.55x, 1 hr = 0.40x, 4 hr = 0.20x, 24 hr = 0.10x, 48 hr = 0.05x. Log interpolation reflects that response time pain compounds non-linearly. The gap between 1 minute and 5 minutes matters less than the gap between 5 minutes and 1 hour, which matters less than the gap between 1 hour and 24 hours. Your effective close rate is the baseline close rate multiplied by your current bucket's multiplier.

The "% after business hours" slider rolls weekends, holidays, lunch, and overnight together. For most US service businesses, total off-hours window is 60-70% of the calendar week (16 off-hours per day plus 48 weekend hours equals 160 of 168 hours), but leads aren't uniformly distributed. We see 25-45% of inbound traffic actually arrive in those windows, depending on industry. Restaurants get more night and weekend leads. B2B SaaS gets more inside-business-hour leads. Set the slider to match your reality, not the calendar.

Yes, almost always. The math of full automation is tempting but rarely the right answer for high-stakes industries (law, real estate, complex B2B sales). The hybrid model uses AI for first contact (sub-1-second answer, qualifying intake, calendar booking) and routes the qualified, hot lead to a human closer who would otherwise have been mid-call. The result is a 5-minute response on 100% of inbound, not 5-minute on 38% of inbound and 4-hour on the rest. Pure AI works for transactional verticals (appointment booking, simple service intake). Hybrid wins almost everywhere else.

It does, implicitly. The baseline close rate you enter is your blended close on all contacted leads, which already reflects whatever drip and re-engagement sequences you run. Speed-to-lead is a multiplier on top of that. The trap is thinking a great 7-touch nurture sequence cancels out a slow first response. It doesn't. The decay study tracked deals all the way through close, including follow-up sequences. The first-vendor-to-respond advantage held end-to-end. Sequences raise close rate. Speed determines whether you ever get into the sequence at all.