What Is a Sales Development Representative (SDR)?

A Sales Development Representative (SDR) is a B2B sales role focused exclusively on prospecting and qualifying potential customers — not closing deals. SDRs run outbound outreach across LinkedIn, email, and phone to book qualified meetings for closers. The role is foundational to most modern B2B sales teams, and one of the most expensive and high-churn hires founders make.

If you've been researching how to scale B2B sales, you've probably run into the term Sales Development Representative — or SDR — over and over. The role is foundational to modern B2B sales, but most explanations of what an SDR actually does are vague enough to be useless.

Here's the practical version: an SDR is a B2B sales rep whose only job is to book qualified meetings. They don't close deals. They don't manage existing customers. They run outbound — LinkedIn, email, phone — and pass qualified prospects to closers (Account Executives or AEs) who run discovery, demo, and contract.

What does an SDR do day to day?

Prospecting and list building

Identifying target accounts and contacts that match the ICP, enriching their data, organizing them into segments.

Multi-channel outreach

Running outbound sequences across LinkedIn, email, and (sometimes) phone. Most modern SDRs use a sales engagement platform to coordinate across channels.

Reply triage and qualification

Reading replies, classifying them (qualified / not qualified / not now), and routing the qualified ones into closer calendars.

Follow-up and nurturing

Re-engaging prospects who showed initial interest but didn't book a meeting on the first sequence.

Pipeline hygiene

Logging activity in the CRM, updating contact records, maintaining clean data.

Why companies hire SDRs

An SDR's value is leverage. A founder or AE who runs their own prospecting can typically generate 4–8 qualified meetings a week. A dedicated SDR running the same time can generate 15–25, while the founder/AE focuses on closing and product.

Why SDRs are expensive

Salary is one-third of the real cost. Add benefits, tools (sales engagement platform, prospecting database, AI assists), manager time, ramp risk (3–4 months unproductive on every new hire), and churn risk (14-month average tenure). The fully-loaded annual cost of one in-house SDR is $130–200K.

The outsourced SDR model

An outsourced SDR (or SDR-as-a-service) is the same function, run by an external team. Cost: $4–8K/month — about 2–3x cheaper than in-house for equivalent activity. Speed: 2–3 weeks to deploy vs. 3–5 months for an in-house hire. Trade-off: you're renting capacity, not building a long-term sales asset.

Most early-stage B2B teams choose outsourced for the validation phase, then bring the function in-house once the motion is clearly working and they have a sales lead to manage it.

Common questions

What's the difference between an SDR and a BDR?

SDRs (Sales Development Representatives) typically focus on inbound qualification. BDRs (Business Development Representatives) typically focus on outbound prospecting. The terms are increasingly used interchangeably — most modern teams have one role doing both.

What's the difference between an SDR and an AE?

SDRs prospect and qualify. AEs (Account Executives) run discovery, demos, pricing, and close. Most B2B teams have a 2:1 or 3:1 ratio of SDRs to AEs to feed the closing capacity.

What's a typical SDR quota?

10–20 qualified meetings booked per month, depending on the motion. Some high-volume SaaS teams run higher; some enterprise teams run lower.

How long does it take to ramp an SDR?

90–120 days to fully productive. The first month is mostly training and ICP learning; months 2–3 are activity ramp; month 4 is when steady-state quota is realistic.

Should I hire an SDR or outsource the function?

Outsource if you need pipeline this quarter, you don't have a sales manager already, you're under 20 employees, or you haven't validated the channel mix. Hire in-house if you have product-market fit, repeatable pipeline, and a sales lead who can coach.