Ingersoll-Rand has reviewed and used drum storage formulas offered in engineering hand books and those of various wire rope manufacturers. We have gleaned the best of these methods and offer this electronic calculator for our customer's convenience. We do not guarantee it will match other rope or winch manufacturers methods or results. Since no restrictions have been placed on the inputs, it is possible to calculate drum sizes that can not reasonably be manufactured. Calculations are for estimating purposes only. Actual drum capacities may vary!