WCAG 2.1 SC 2.5.5 (Target Size, AAA) and Apple's Human Interface Guidelines both recommend at least 44 by 44 CSS pixels so a fingertip can reliably hit the control without mis-tapping a neighbour.

What is the 24px AA option?

WCAG 2.2 added SC 2.5.8 (Target Size Minimum, AA) with a lower floor of 24 by 24 CSS pixels, intended as a practical baseline when 44px is not feasible and there is adequate spacing around the target.

How are rem and em converted?

The tool assumes the common default root font size of 16px, so 1rem equals 16px and, for this calculation, 1em is also treated as 16px. Adjust your expectation if your root font-size differs.

Does padding count toward the target size?

Yes. The clickable target includes the element's padding and any pseudo-element hit area, so size your buttons using their full rendered box, not just the text. Enter the total rendered width and height here.

Is anything sent to a server?

No. All unit conversion and comparison runs in your browser; nothing is uploaded.

Touch-Target Size Checker

The Touch-Target Size Checker converts your control’s width and height into CSS pixels and tells you whether it clears the size thresholds that keep buttons and links comfortably tappable. Under-sized targets are one of the most common mobile accessibility failures, and the fix is simply to grow the hit area.

How it works

You enter a width and height, each with its own CSS unit, and the tool converts both to pixels using fixed CSS conversion factors:

1 px  = 1 px
1 pt  = 96/72 px  = 1.3333… px
1 in  = 96 px
1 pc  = 16 px
1 mm  = 96/25.4 px ≈ 3.7795 px
1 cm  = 96/2.54 px ≈ 37.795 px
1 rem = 16 px        (default root font-size)
1 em  = 16 px        (treated as root for this check)

It then compares each pixel value against the chosen minimum:

44 px — WCAG 2.1 SC 2.5.5 (AAA) and Apple HIG.
24 px — WCAG 2.2 SC 2.5.8 (AA) minimum floor.

A dimension passes when it is greater than or equal to the threshold. If it falls short, the checker reports the exact pixel deficit so you know precisely how much padding or sizing to add.

Example

A button declared width: 2rem; height: 2rem converts to 32 × 32 px. Against the 44px AAA target it fails both dimensions by 12 px each; against the 24px AA floor it passes. Growing it to 2.75rem (44px) satisfies the AAA recommendation.

Tips

Always size the full rendered box including padding — that is the real tap area, not the text glyphs.
When two targets are close together, give them margin as well as size; WCAG’s AA floor assumes adequate spacing.
Aim for 44px wherever the layout allows; reserve the 24px floor for genuinely dense interfaces.