MISB is the highest pre-grade claim for sealed LEGO — factory-sealed AND Mint condition. AFA 90 / CGC 9.5 is the target outcome. But 70% of self-described MISB submissions return Near Mint or below. Pre-grade with BrickGauge to confirm before paying the slab fee.
MISB stands for Mint In Sealed Box — a sealed LEGO set claimed to be both factory-sealed AND Mint condition across all visible axes (seal, corners, edges, surface, print, structural). MISB is the highest pre-grading claim a seller can make, targeting AFA 90+ (Mint) and CGC 9.5+ at submission. But MISB is a seller's claim, not a verified grade: across audited submissions, only about 30% of self-described MISB boxes actually return AFA 90+, with 45% landing at AFA 85 Near Mint and 25% at AFA 80 or below. Pre-grading with BrickGauge before submission verifies the claim against the six-axis rubric in 38 seconds.
The terminology hierarchy and what each claim implies for grading outcomes. MISB is the highest claim; only MISB and NISB are eligible for AFA / CGC sealed-box grading.
| Term | What it claims | Grading implication |
|---|---|---|
| MISB (Mint In Sealed Box) | Factory-sealed AND Mint condition on every axis | AFA 90+ / CGC 9.5+ target — pre-grade to confirm |
| NISB (New In Sealed Box) | Factory-sealed but condition unspecified | AFA 75 – 90 possible — pre-grade required |
| Sealed | Factory-sealed only — no condition claim | AFA 70 – 90 — pre-grade to set expectations |
| NIB (New In Box) | Box present but seal may be broken | Not eligible for sealed-box grading at AFA / CGC |
| Loose / Open | Box opened, contents may be complete or partial | Not eligible for sealed-box grading |
BrickGauge confirms Mint on all six axes with ≥85 confidence. Submit at AFA Standard ($25) or CGC Economy ($23) — the AFA 90 premium typically clears the round-trip cost.
Borderline. One axis (usually corners or edges) dragging the call. Re-shoot under raking light to confirm; if confidence drops below 85, label as NISB and target AFA 85 instead.
Box doesn't clear MISB thresholds. Submitting risks AFA 80 — where the slab can reduce resale below raw. Sell raw as 'sealed' instead, or pre-grade after better photos.
Six checks must all pass for true MISB status: (1) factory seal intact with no reseal indicators detected; (2) all four corners under 1mm compression (worst-corner rule applies); (3) edge whitening under 2% of total perimeter; (4) no detectable surface scratches at arm’s length; (5) no print drift against the box underside reference; (6) pristine seal sticker with no corner lift. Run all six photos through BrickGauge — the AI catches whichever axis falls short and tells you exactly what would push the box into Mint territory.
MISB self-classification has a 70% under-call rate at AFA / CGC. BrickGauge runs the same six-axis rubric the graders use, calibrated against 240,127 published grades at ±0.5 accuracy. Two scans free on signup, no credit card.
MISB stands for Mint In Sealed Box — meaning a LEGO set that is both factory-sealed AND in Mint condition across all visible axes (seal, corners, edges, surface, print, structural). MISB is the highest pre-grading claim a seller can make on a sealed LEGO box. AFA's Mint tier (90+) and CGC's Mint tier (9.5+) are the corresponding grade outcomes.
Often yes — MISB claims target the AFA 90 / CGC 9.5 tier where the resale premium over raw is 80–150% on flagship sets. But MISB is a seller's claim, not a verified grade. Pre-grade with BrickGauge before submitting to confirm the box actually clears Mint thresholds on all six axes. The worst-corner rule catches a lot of self-described MISB boxes.
MISB (Mint In Sealed Box) claims factory-sealed + Mint condition. NISB (New In Sealed Box) claims factory-sealed only — condition is unspecified. NISB is the more accurate claim for most sealed LEGO because true Mint condition requires sub-1mm corners, sub-2% edge whitening, and no print drift. Many 'MISB' listings are actually NISB at AFA 80–85.
Yes — and it's common. The worst-corner rule (graders score the worst of four corners, not the average) catches MISB boxes with one back corner over 1mm. Edge whitening percentage is also tighter than collectors typically estimate. Pre-grade with BrickGauge to catch these gaps before submitting.
Targeting AFA 90 (Mint) — but actual outcomes vary. Across audited MISB submissions: about 30% return AFA 90+, about 45% return AFA 85, about 20% return AFA 80, and 5% return below. The 70% under-call rate is why pre-grading matters even on confidently-described MISB boxes.
Six checks: (1) factory seal intact with no reseal indicators, (2) all four corners under 1mm compression, (3) edge whitening under 2% of perimeter, (4) no detectable surface scratches at arm's length, (5) no print fade against the underside, (6) pristine seal sticker with no lift. Run all six photos through BrickGauge — the AI catches whichever axis falls short.
Only if you're confident. Mis-labeling NISB boxes as MISB damages your seller reputation and triggers chargebacks when buyers pre-grade with BrickGauge. The safer call: list as 'sealed' with a BrickGauge pre-grade screenshot showing the actual axis scores. Buyers trust verified data more than condition claims.
No — MISB combines two separate claims: factory-sealed (the box) AND Mint condition (the visible state). A box can be Mint without being sealed (Mint, opened), or sealed without being Mint (sealed but with corner compression). MISB requires both simultaneously. Pre-grade with BrickGauge to verify the second claim quantitatively.
