Poly Tubing Cut-Length Yield With End Allowances

To estimate tubing yield, divide the available roll length by the full length consumed for one cut piece. Include the material needed at both ends, not just the length of the item. Round down to complete pieces and keep setup losses separate.

The examples use PT0502, a 5-inch x 2,150-foot clear polyethylene tubing roll, and PZT1202, a 12-inch x 1,000-foot clear polypropylene tubing roll. Both are listed as 2 mil and sold as one roll. Their different widths and materials must be qualified separately; the arithmetic below does not make them substitutes.

Define one complete cut length

Write down the item's complete protected length, the material consumed at the first end, and the material consumed at the second end. Each end allowance must come from the actual approved forming and closing method. Include any further material consumed between repeat cuts in the recorded cut pitch rather than forgetting it.

For this hypothetical calculation only, assume a 12-inch item envelope and an established 1-inch allowance at each end. Also assume no additional length is consumed between repeat cuts. The full cut pitch is therefore 12 + 1 + 1 = 14 inches. The one-inch values are example inputs, not instructions for sealing either film.

Convert the roll length before dividing

For PT0502, 1,842 pieces consume 25,788 inches, leaving 12 inches. That remainder is too short for another 14-inch piece. For PZT1202, 857 pieces consume 11,998 inches, leaving 2 inches. The formula is complete pieces = floor(available inches ÷ cut pitch).

Show what happens when the end zones are omitted

Dividing PT0502's 25,800 inches by the item's 12-inch length alone would suggest 2,150 pieces. Under the hypothetical 14-inch method, only 1,842 full cut pieces result, a difference of 308. The larger count omitted the material needed at both ends.

Do not fix this by reducing the allowance on paper. If a different method uses less material, establish that method with the actual film and item, then revise the cut pitch. A spreadsheet change cannot establish a suitable closure.

Separate cut pieces from finished bags

The table assumes the entire listed roll length is available and every cut is made at the same pitch. It excludes material used for setup, irregular first cuts, rejected pieces and other process consumption. Subtract separately measured unusable or reserved length from the available roll length before calculating a production estimate.

After conversion, record complete blanks produced and finished bags accepted as different counts. A correctly sized blank may still be consumed in a trial or rejected during forming. The number of complete cut pieces is not a guarantee of usable bags or product protection.

Keep the calculation with the converting method

Save the exact tubing SKU, available roll length, cut pitch, end allowances and separate setup consumption. Repeat the calculation when the item envelope or converting method changes. Keep width suitability and material compatibility outside the length arithmetic.

Review the custom-bag tubing guide when narrowing the source roll. Use the complete cutting plan, rather than the item's length alone, to estimate what the selected roll can produce.