The hamburger menu — that three-line icon (☰) in the top corner — collapses a site's navigation into a single tap target. It solved a real problem when smartphones arrived and horizontal space became precious. But it has a significant cost: hidden navigation gets used 50-75% less than visible navigation, according to multiple NNGroup studies.
For landing pages specifically, the hamburger menu question is often moot because you shouldn't have much navigation at all. The best-converting landing pages for paid traffic have minimal or no top navigation — just a logo and maybe a single CTA link. Adding a hamburger menu with your full site nav on a focused landing page is giving visitors escape routes you don't want them to take.
When the hamburger makes sense
On mobile, it's often unavoidable for content-rich pages. If your landing page has anchor links to sections (pricing, features, FAQ), a hamburger containing those section links is reasonable. But for a focused paid-traffic landing page, you'd be better off with no navigation at all than hiding options in a hamburger that 70% of visitors won't open.
If you must use a hamburger on desktop, pair it with a visible CTA button that stays outside the menu. The pattern of "hamburger on the left, CTA button on the right" in the nav bar gives you minimal nav distraction while keeping the conversion action always visible. Never bury your CTA inside a hamburger menu.