A tool for calculating the maximum angle of inclining conveyors for boxes and containers Please note that your boxes material will give different results to the below calculation. This calculation is meant for a standard cardboard box, plastic containers and boxes generally have less grip than cardboard due to the smooth surface which would give a lower angle result than this would suggest whereas products made from something like rubber would have more grip and allow a steeper incline than suggested. This calculation is also for boxes with evenly distributed weights. The maximum incline angle we recommend is around 27 degrees without using a cleated belt. With one we could go up to around 45 degrees depending on the product.