Disclosure: figures below come from documented host support pages and MySQL's own defaults, not our own load-testing rig — where we couldn't find a host's published number, we say so instead of guessing.
“How many concurrent connections can my database handle?” only matters once you're running more than one site on the same account, or one site with real simultaneous traffic. The honest answer is that most budget shared-hosting plans hit a real, documented connection ceiling well before they hit any advertised traffic or storage limit — and that ceiling is rarely the number hosts lead with in their marketing.
What “max_connections” Actually Limits
Every MySQL/MariaDB instance caps the number of simultaneous client connections it will accept (the max_connections system variable, 151 by default on a stock MySQL 8.0 install). On shared hosting, this cap is usually set much lower and applied per-account rather than per-server, since one account's runaway connection count would otherwise starve every other tenant on the same box. Hitting it produces a “Too many connections” or “user <account> already has more than max_user_connections acti