What is a partial 401(k) match versus a dollar-for-dollar match?

A dollar-for-dollar (full) match adds one dollar for every dollar you contribute up to a cap, so a 100% match on the first 4% of pay gives you 4% free when you defer 4%. A partial match adds a fraction, such as 50 cents per dollar; a 50% match on the first 6% gives you 3% free when you defer 6%.

To capture the maximum, you must contribute up to the cap of pay the formula references, not just match the stated percentage. Read your formula carefully, because a 50%-on-6% plan requires a larger deferral than a 100%-on-3% plan to earn full value. Either way, the match is an instant guaranteed return you cannot get anywhere else, so prioritize hitting the cap.