Filing a weak chargeback wastes your one shot — and filing a dishonest one can cost you your account. Answer a few questions first. You get an honest verdict band, the reason-code family your situation belongs to, and the three evidence points that will decide it. No percentages. No promises.
Search for "will I win my chargeback" and you will find tools implying a probability. That number cannot exist honestly: your issuer decides your case on the evidence in front of it, the merchant gets to respond, and outcomes vary by issuer, network, and paperwork quality. What can be assessed — and what this checker does — is the structure of your case: whether it fits a recognized dispute category, whether the proof that category requires exists, and whether you are inside the clocks.
Strong case — your situation fits a recognized reason-code family, the deciding evidence is the kind you can actually produce, and you are inside the deadlines. File now; delay is the only remaining risk. Mixed case — the underlying problem is real, but something material is missing: no merchant contact yet, no cancellation proof, continued use after the problem, or a clock that is running out. The verdict names the gap so you can close it before filing. Weak case — the situation has no valid dispute family (buyer's remorse), the facts contradict the claim (a "cancelled" subscription that was never cancelled), or the charge was made by your own household. Filing anyway is how accounts get flagged and closed — the verdict gives you the route that actually works instead.
Issuers and networks decide on category + evidence + timing. Category comes from the published reason codes — Visa's Dispute Categories 10 (fraud), 12 (processing errors) and 13 (consumer disputes); Mastercard's 48xx family; Amex's lettered codes. Evidence is weighed against what the merchant can produce: delivery scans beat "it never came", a dated cancellation confirmation beats "I meant to cancel", and a merchant's written refund promise beats everything. Timing is brutal and simple: outside the network window (typically ~120 days) or the legal statement window (60 days under US FCBA/Reg E rules), even a true story usually cannot be filed. The companion guides go deeper: what makes a chargeback case strong or weak, matching your situation to the right reason code, and when NOT to file a chargeback.