Climbing Rope Length Finder

The rope length math for a route

A rope has to travel up a route and back down, so the math is mostly doubling. Lowering a climber from the anchors or top-roping means the rope runs from the climber up to the anchor and back to the belayer. That takes twice the route height. Add an allowance for the tie-in knot, the belay device and rope stretch, and you have the minimum length. This finder uses 10 ft by default, and you can edit it. It is length math only, not a safety check.

Rope systems change the formula only for rappelling. Wikipedia notes that dynamic ropes can be single, half or twin ropes, each with its own specification. For lowering, each half or twin rope must still be as long as a single rope would be. For rappelling on two tied ropes, the distance is about one rope length, so each rope needs only the route height plus half the allowance.

Here is a worked example. A sport route is 80 ft tall, you use one rope, and you want to lower off. Twice 80 is 160, plus a 10 ft allowance gives 170 ft, or 51.8 m. A 50 m rope is 164 ft, which is too short. A 60 m rope is 197 ft and covers it with 27 ft to spare. Reverse the math to find the tallest route a rope handles: subtract the allowance, then divide by two.

Route height comes from a guidebook or topo, and those numbers can be rounded, so the allowance is worth keeping generous. Longer pitches call for longer ropes or a split into two pitches. To compare grade scales across areas, use the climbing grade converter, and to count the weight you carry to the crag, use the pack weight calculator.

Where these numbers come from

The formulas and default values in this calculator are based on:

• Wikipedia, Climbing rope (dynamic ropes can be single, half or twin)
• standard 50, 60, 70 and 80 m lengths
• 1 m = 3.28084 ft. Note: the doubling formulas and the 10 ft allowance are planning math, and this page gives no safe or unsafe verdict

This is a planning estimate, not medical, legal or immigration advice. Fees, allowances, limits and entry rules change, so confirm the figures with your airline, cruise line, customs agency or the official government source before you book or travel, and follow their rules if they differ from this page.