tape measure; measuring tape
A flexible ruler used for measuring length, often retractable or rolled up.
I measured the width of the room with a tape measure.
The carpenter measured the length of the lumber with a tape measure.
I bought a measuring tape for sewing.
I pulled out the tape measure to check the height of the tree.
When you're done, retract the tape measure and put it away.
物差し is a rigid, flat ruler used for straight measurements, whereas 巻尺 is a flexible tape that rolls up and can measure curved or long distances.
Used for 巻尺 (measuring tape) because it's a long, thin object, like other 細長い tools counted with 本.
Standard kanji spelling; the most common written form.
Alternate spelling with okurigana; less common but still encountered.
Compound of 巻く (maku, 'to roll up') + 尺 (shaku, a traditional unit of length, here meaning 'measure'). The reading じゃく is a rendaku form of 尺.