MQL vs SQL: what is the difference?

Written by Madalena Rugeroni, founder of Mazo · Updated 10 November 2026

A marketing qualified lead (MQL) is a lead that marketing judges likely to buy based on fit and engagement, such as someone from a target company who downloaded a pricing template. A sales qualified lead (SQL) is a lead sales has checked, usually in a conversation, and accepted as worth working as a real opportunity.

MQL to SQL conversion rate

MQL → SQL conversion rate = SQLs created from MQLs ÷ MQLs in the same period × 100

Use a cohort: count how many of this month's MQLs became SQLs, even if the conversion happens next month. A low rate means marketing's definition of "qualified" and sales' definition don't match yet.

Worked example

A fictional SaaS defines an MQL as a lead from a company with 50–500 employees, in a target industry, who requested a demo or visited pricing twice.

In March it gets 400 sign-ups and content downloads, of which 80 meet the MQL definition.
Sales talks to 60 of them; 24 have a real problem, a budget holder involved and a timeline, so they become SQLs.
MQL → SQL rate = 24 ÷ 80 = 30%. The 20 MQLs sales never called are the cheapest pipeline to recover.

Why it matters from €0 to €1M ARR

Pre-revenue to first customers: skip the labels. The founder talks to every lead and decides on the call.
Steady inbound: write down one sentence for each: "An MQL is… An SQL is…". Agree it with whoever does sales.
With a sales team: track conversion at every stage (lead → MQL → SQL → won) to find where pipeline leaks.

Mazo's rule of thumb: define an SQL by what the buyer told you (a problem, a person who can buy, a reason to act now), never by what they clicked. Clicks can make a lead an MQL; only a conversation makes it an SQL.

Common MQL and SQL mistakes

Counting every download as an MQL. It inflates marketing numbers and wastes sales time.
No agreed definition. Marketing and sales argue about lead quality instead of fixing it.
Never following up on rejected MQLs. Recycle them into nurture with a reason code.
Optimising for MQL volume. Judge marketing on SQLs and pipeline.

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FAQ

What is the difference between an MQL and an SQL?

An MQL is judged likely to buy based on data: company fit and engagement such as visits, downloads or sign-ups. An SQL has been checked by sales, usually in a conversation, and accepted as a real opportunity worth working.

What is a good MQL to SQL conversion rate?

It depends heavily on how strictly you define an MQL, so compare against your own trend. A very low rate usually means the MQL definition is too loose or sales is not following up.

What comes after an SQL?

Once sales has run discovery and confirmed the deal, the SQL becomes an opportunity in the pipeline, which then closes as won or lost.

Who wrote this

Madalena Rugeroni built Mazo. She's an ex-Googler, a startup advisor and investor, and runs a portfolio of internet companies. Before that, as Head of Growth at Amplemarket, she scaled a B2B SaaS to $10M ARR. LinkedIn

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Further reading. Staged lead definitions such as MQL and SQL were popularised by SiriusDecisions' Demand Waterfall. Mazo is not affiliated with or endorsed by SiriusDecisions or its owner.