Every reseller account has an underlying resource ceiling set by your hosting provider (total disk space, bandwidth, number of accounts) — how you divide that among client packages is entirely up to you, within that ceiling.
Checking your own allocation
WHM’s home page or Account Information section shows your total allocated resources and how much is currently in use across all your client accounts combined — this is the real ceiling you’re working within, regardless of what limits you set on individual packages.
What “overselling” actually means
Overselling is setting package limits (e.g. “unlimited” disk space, or generous per-account limits) that add up to more than your reseller account’s actual total allocation, betting that most clients won’t use their full allotted limit simultaneously. This is standard industry practice and generally works fine — until enough clients grow their usage at once that real demand exceeds your real capacity.
The risk in practice
If your combined client usage approaches your actual reseller ceiling, you’ll start hitting resource limits at the account level — new accounts may fail to create, or existing accounts may be constrained, regardless of what their individual package promised them. This is a business/capacity planning risk, not just a technical one: it directly affects client experience if you’ve oversold too aggressively.
Managing it responsibly
- Monitor your total usage (not just individual account limits) regularly, not just when something breaks.
- Set realistic package limits based on typical usage patterns you actually observe, not just what sounds attractive in marketing.
- Upgrade your own reseller plan proactively once total usage trends toward your ceiling, rather than waiting for it to become a client-facing problem.
The honest version of “unlimited”
“Unlimited” in a client-facing package almost always really means “no hard per-account cap, bounded by fair use and by your reseller account’s real total capacity” — understanding that distinction yourself is essential to not accidentally overselling your way into a capacity crisis.