Count the job ads first.

Not as a number — prices, recognition and salary effects vary by field, country, employer and year, and anyone who quotes you a figure confidently is guessing or selling. What it gives you is the method that produces a real answer: tally thirty job ads for your target titles into required, preferred and not mentioned, then ask two people who actually hire. That's an hour's work and it beats every marketing claim.

Because they're usually published by the bodies selling the exam, and because the people who take certifications are often already progressing — motivated, senior, in growing fields. The certificate gets credit for what those people would likely have achieved anyway. Your own job ad count has no such bias.

More than the exam fee. In the calculator, a 550 exam plus a 1,200 course, 120 annual dues and 120 study hours at 30 an hour comes to 5,470 in the first year — with 3,600 of that being your time, and 24 weeks of study at five hours a week. If your employer pays the fees, the same thing costs 3,720, almost all of it time.

Often. A stretch project at work, an internal secondment, a portfolio piece or a short focused course can produce evidence you've done the work, which many employers value more than proof you studied it. The comparison tool weights that against your own job ad count — where the credential is genuinely required, it wins; where it barely appears, the free route usually does.

Who awards it and whether that body is recognised in your field — be wary of credentials that are quick, expensive, guaranteed to pass, or accredited by organisations nobody in the industry mentions. Check renewal fees and continuing education hours, since many lapse without them. And ask your employer to fund it first: many will, most people never ask, and if they do, read the clawback clause about repaying if you leave.