Bow Rehair Timeline Calculator

A bass bow needs significantly more bow pressure and rosin to drive its thicker, lower-pitched strings than a violin bow does, so the hair accumulates friction wear and rosin buildup faster per hour played, even though that wear is spread across a wider ribbon of hair. That's why the calculator applies a larger reduction to the adjusted-hours budget — and therefore a shorter rehair interval — as bow size increases from violin through bass.

Bow hair is a natural protein fiber that absorbs and releases moisture from the surrounding air, and dry conditions make it more brittle and prone to breaking or losing its grip on rosin. Humid conditions keep the hair more supple, which is why the calculator estimates a longer usable interval in humid climates and a shorter one in dry climates.

Look for visible thinning, broken or missing strands, hair that's gone slick and won't hold rosin well, or a noticeably weaker sound and response — a rating near 10 means the hair still looks and performs like new, while a rating near 1 means it's clearly due for replacement. If you're unsure, a luthier or string teacher can give you an objective assessment in a few seconds.

No — 200 hours is a commonly cited general reference point for typical playing conditions, but actual bow hair life varies with individual playing style, how much pressure and rosin you use, and the specific hair quality on your bow. Treat the estimate as a planning guideline and confirm with a visual and feel check rather than replacing hair strictly by the calculated date.

The urgency score is derived directly from your current hair condition rating alone, giving an at-a-glance sense of how close the hair already is to needing replacement regardless of your playing schedule. The weeks estimate additionally factors in how quickly you'll use up the remaining hair life at your playing pace, so a low-hours player with worn hair can see a high urgency score but a longer weeks-until-rehair estimate.