Index card sizes

Choose an index card for a box, filing system or print job. Compare inch sizes with A7 and A6, including centimetre conversions.

Index card / Standard (3 by 5)

A Standard (3 by 5) index card measures 3 × 5 in (76.2 × 127 mm), published in inches by Avery.

Nominal size: 3 × 5 in76.2 × 127 mm900 × 1500 pxat 300 dpi

Source retrieved 2026-09-16. Reviewed 2026-09-16.

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Specifications and evidence

The common size; ruled or blank, sold in packs of one hundred.

Reviewed: 2026-09-16

Reference in inches. 3 × 5 in converts to 76.2 × 127 mm (1 in = 25.4 mm). A calculated conversion does not add measurement precision.

Index card size diagram: 76.2 by 127 mm, 3 by 5 inches, drawn to scale. — DrawingIndex card. Proportional drawing; grid squares represent 10 mm.
Index card drawingDownload SVG · PNG · reuse with credit

Dimensions

Dimensions of Index card variants in millimetres, inches and pixels
Variant	mm	in	px at 300 dpi	px at 600 dpi	Specified in
Standard (3 by 5)inch reference	76.2 × 127	3 × 5	900 × 1500	1800 × 3000	inches
Large (4 by 6)inch reference	101.6 × 152.4	4 × 6	1200 × 1800	2400 × 3600	inches
Extra large (5 by 8)inch reference	127 × 203.2	5 × 8	1500 × 2400	3000 × 4800	inches
A7 (metric)mm reference	74 × 105	2.91 × 4.13	874 × 1240	1748 × 2480	millimetres
A6 (metric)mm reference	105 × 148	4.13 × 5.83	1240 × 1748	2480 × 3496	millimetres

Pixels

Variant	px at 300 dpi	px at 600 dpi
Standard (3 by 5)	900 × 1500	1800 × 3000
Large (4 by 6)	1200 × 1800	2400 × 3600
Extra large (5 by 8)	1500 × 2400	3000 × 4800
A7 (metric)	874 × 1240	1748 × 2480
A6 (metric)	1240 × 1748	2480 × 3496

Inch sizes and ISO paper sizes

Choose by the box, divider or filing system the card must fit. A7 and A6 are ISO paper sizes, not metric names for the nearby inch-based products. A matching rectangle also does not establish paper thickness or printer compatibility.

Avery 5388 uses printable sheets with three detachable cards, each finishing at 3 × 5 in. The sheet passes through the printer. Before feeding loose index cards, check the printer’s supported stock and media path.

Questions

What size is an index card in millimetres and centimetres?

A 3-by-5 card is 76.2 × 127 mm, or 7.62 × 12.7 cm. The larger 4-by-6 and 5-by-8 cards convert to 10.16 × 15.24 cm and 12.7 × 20.32 cm respectively. All are calculated from the products’ stated inch sizes.

Is a 4 by 6 index card the same as A6?

No. A6 is 105 × 148 mm: 3.4 mm (0.13 in) wider and 4.4 mm (0.17 in) shorter than the 4-by-6 card. A box or divider cut for one will not necessarily suit the other.

How do A7 and A6 relate to A4?

Each ISO A size is made by halving the previous size across its long edge, with dimensions stated in whole millimetres. A6 is approximately a quarter of an A4 sheet and A7 an eighth. For accurate finished cards, mark the listed dimensions rather than relying only on folded edges.

Are index-card and photo sizes interchangeable?

They can share a nominal rectangle, but that does not establish equal coating, thickness, feed direction or cut tolerance. Match the actual product and equipment.

Postcard size6 × 4 in
Business card size3.5 × 2 in
Tarot card size2.75 × 4.75 in
Card size chartevery format on one plate

See how Card Dimensions checks sizes and distinguishes published figures from measurements.