A standard compact disc is 120 mm across and 1.2 mm thick; mini CDs measure 80 mm in diameter.
Curious about disc sizes for storage, packaging, or gear fit? This guide lays out the exact measurements, what varies, and how those figures translate to capacity and cases. You will see the standard 120 mm profile, the smaller 80 mm option, and shaped releases that still follow core rules. Clear specs help with printing inserts, cutting foam, or checking a slot on a drive tray. If you landed here asking, How Big Are CDs? the short specs appear right below and then in detail throughout the sections.
How Big Are CDs? Size Standards You Can Use
The compact disc format locks in two common diameters: 120 mm for the full-size disc and 80 mm for the mini disc. Both share the same nominal thickness of 1.2 mm and a 15 mm center hole. The program (data) area starts near a 25 mm radius and ends near 58 mm. Those dimensions come from the optical format spec and keep discs interchangeable across players and drives.
- Check the outer diameter — Full size is 120 mm; mini is 80 mm. That’s the number you need when cutting sleeves or foam.
- Confirm the thickness — Plan on 1.2 mm for the polycarbonate substrate plus a lacquer and label layer that adds only a hair.
- Mind the center hole — 15 mm across, which matches the clamping hub on trays and spindles.
Quick check: if a slot-loading drive lists only 120 mm media, avoid feeding an 80 mm disc unless the maker says it’s okay.
CD Dimensions At A Glance
Here are the core numbers people ask for when sizing templates, boxes, and mounts. Values below match the optical format spec for pressed audio and data discs; recordable discs follow the same outer geometry.
| Measurement | Standard CD (120 mm) | Mini CD (80 mm) |
|---|---|---|
| Diameter | 120 mm | 80 mm |
| Thickness | 1.2 mm | 1.2 mm |
| Center Hole | 15 mm | 15 mm |
| Data Area (inner/outer radius) | 25 mm / 58 mm | 24–26 mm / ~39 mm |
Template tip: when you prepare artwork, keep print elements at least 2 mm from the edge and the hub to avoid clipping during trimming. Keep inks thin and even.
Table notes: the inner and outer radii mark where data begins and ends. The playable ring never reaches the very edge; that clear rim protects the spiral from chips. The hole and clamping ring are part of transport mechanics, not the data path, so artwork that bleeds into the clear hub won’t affect reading but can look uneven if the hub is textured.
Variations: Mini, Business Card, And Odd Shapes
Beyond the full-size disc, the 80 mm mini disc shows up with drivers, music singles, or small handouts. It works in tray-loading drives that accept 8 cm media. Capacity drops with the smaller circumference, but the thickness and center hole stay the same, so handling and packaging feel familiar.
- Mini CD (80 mm) — Holds about 185–210 MB of data or up to 24 minutes of audio, depending on data density used by the manufacturer.
- Business card CDs — Rectangular or rounded-rect shapes near 85 × 54 mm aim to match a wallet card. They carry less data because the playable ring is short.
- Shaped discs — Hearts, ovals, and other silhouettes exist. They still keep a circular data ring with the same hub and track geometry, so many players can read them, but drive makers often warn against them in slot mechanisms.
Business card discs trade area for a pocket-friendly outline. Shapes near 85 × 54 mm mimic a bank card, yet the data still sits on a short circular band. Because the outer corners don’t carry data, scratches there won’t affect playback, but impacts near the inner ring can. Many slot drives reject shaped media, so a tray is the safe pick.
Shaped media looks fun, but stick to standard 120 mm or 80 mm discs when you need wide playback and easy replication. Odd shapes can rattle in drives, and some vendors won’t press them at all.
CD Size Guide With Measurements
This section steps through every dimension that affects cases, trays, sleeves, and storage. Use a caliper if you need precise fits; small errors add up when you print inserts or cut foam.
Outer Diameter And Tolerances
The nominal outer diameter is 120 mm. The standard allows only tiny variation so the disc clears the tray walls and fits into retail packaging. Mini discs use 80 mm. Shaped discs still rely on a 120 mm or 80 mm circular data ring even if the plastic outline looks different.
Center Hole And Clamping Ring
The center hole measures 15 mm. Around it sits the clamping ring that the drive grips. If you design hubs or spindles for storage, give a little clearance and use a gentle taper so the disc lifts without bending. Avoid tight hubs that stress the clear inner plastic.
Thickness And Label Layers
Disc thickness is 1.2 mm for the polycarbonate body, with a thin reflective metal film and a lacquer coat on top. Recordable media adds a dye layer under the lacquer. Paper labels can tilt a disc if applied unevenly, which can lead to read errors at high speed. Direct-print or printable coatings keep balance better.
Program Area And Track Pitch
Data lives in a spiral that starts near a 25 mm radius and ends near 58 mm. The track pitch is about 1.6 µm. Pit length varies along the spiral, which carries Eight-to-Fourteen Modulation bits and error correction. You don’t need that math to pick a case, but those figures explain why capacity scales with diameter.
How Big Are CDs? Packaging, Cases, And Shelf Fit
Most buyers still know the classic jewel case that launched with the format. If you’re planning shelves, boxes, or mailers, these are the common outer sizes you’ll run into on full-size discs. Mini discs often ship in sleeves or small jewel-style boxes built around the 80 mm footprint.
- Jewel case (standard) — About 142 × 125 × 10 mm. Good for retail racks and printable spines.
- Slimline jewel — Similar length and width, about half the thickness, handy for mailers.
- Card sleeves and digipaks — Thickness varies with board weight. Add a millimeter or two of slack if you are designing tight slots.
Deeper fix: if a sleeve scuffs discs, add a smooth liner or switch to a tray with raised tabs that hold the rim instead of the label side.
Capacity, Pits, And Track Pitch Explained
Size and data density set how much a disc holds. A 120 mm disc with 74 minutes of audio carries about 650 MB of data. The common 80-minute disc maps to about 700 MB. The spiral’s track pitch and pit length define that mapping. A smaller 80 mm disc offers less perimeter for the spiral, so capacity drops to roughly a third.
- Standard capacities — 74, 80, 90, and 99-minute audio variants exist; in data terms you’ll see about 650, 700, 800, and 870 MiB.
- Why the numbers — Track pitch near 1.6 µm and minimum pit length near 0.83 µm set the symbol budget around the spiral.
- Mini disc capacity — Typical blanks list 185–210 MB, which lines up with 21–24 minutes of audio at Red Book rate.
Some rare formats squeezed more data by tightening pitch or pit length, but they never saw wide adoption. For planning, stick to 650–700 MB for 120 mm discs and about 210 MB for 80 mm discs.
Fit And Use: Drives, Trays, And Handling
The geometry above ties directly to safe use. Slot-loading drives that lack an inner recess can jam on 80 mm media or shaped discs. Trays with a second ring handle both sizes with no fuss. Many car players and slim laptops only list 120 mm media; feeding a mini disc in those slots can brick the mechanism. If a friend asks, How Big Are CDs? give them the quick spec and warn about slot drives that reject 80 mm media.
- Match the drive — Read the front panel or the manual. Look for an 8 cm mark or a second inner recess on the tray.
- Handle the rim — Grip the edge or the hole. Keep fingers off the label on thin-coated pressings to avoid scratches that reach the metal.
- Avoid heat and flex — Long sun exposure or bending can craze the polycarbonate and ruin reflectivity.
- Pick by task — Use 120 mm for retail or archives; use 80 mm for handouts when tray drives are available.