Corrugated RSC Blank Size and Web Trim Waste Calculator
A regular slotted container blank is four panels, a glue joint and two sets of flaps. This calculator converts inside dimensions into the blank you actually cut, then shows how many fit across your web and how much board you throw away as trim.
Your numbers
Inside length of the finished box.
Inside width of the finished box.
Inside depth between the flap folds.
Typical glued or stitched joint tab is 30 to 50 mm.
Extra material per score line for the board caliper. Depends on flute and your plant standard.
Usable width of the board that comes off the corrugator.
Price or standard cost per square metre of finished board.
Your results
Blank dimensions follow the common RSC layout. Your plant scoring tools, flute and customer standard may add or subtract a few millimetres. Confirm with a sample cut.
Trim waste vs web width
Sweeps Corrugator web width from 1000 to 2500, holding your other inputs fixed.
Automate blank and trim costing
Optional review of how to calculate blank size, ups and trim cost from your ERP item and routing data.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the inside length, width and height of the box, the joint width and a score allowance. Then enter the usable web width of your corrugator and the board price. The result shows blank size, the number of blanks across the web, trim in millimetres and percent, and the cost of board per box once trim is allocated. Use the chart to see how trim changes as the web width moves. A small change in the web you run can swing waste by several percentage points.
The formulas behind it
For an RSC the blank length is 2 x (L + W) + joint + score allowances, and the blank width is H + W + score allowances, because the two flaps are each half of the box width and meet at the centre. The number across the web is floor(web / blank width). Trim is web minus ups times blank width. Board per box is blank length times web width divided by ups, which charges trim to the box.
- Blank length = 2 x (L + W) + joint + 4 x allowance
- Blank width = H + W + 2 x allowance
- Ups = floor(web width / blank width)
- Trim % = (web - ups x blank width) / web
Reading the result and common mistakes
If trim is above roughly 5 to 8 percent, look at combining orders on the same web, running a different web width, or asking the customer whether the box can move a few millimetres. Mixing up inside and outside dimensions is the most common error, and it produces boxes that are too large by twice the board caliper. Also check which direction the flutes run, since customers often specify it for stacking strength.
- Use inside dimensions, not outside
- Check score allowance for your flute type
- Remember slotter trim and side trim on the corrugator
- Sweep the web width before accepting high trim
Frequently Asked Questions
Why is the blank width height plus width?
An RSC has two flaps on each end, each roughly half the box width, so they meet in the middle when closed. The blank must cover the height plus both half-width flaps, which adds up to the full width once.
What score allowance should I use?
It depends on flute type and your creasing tools. Thin flutes need very little, thick flutes more. Use your plant standard or measure a sample, then enter the per-fold value here.
Does this include corrugator side trim?
No. Enter the usable web width after edge trim. If your trim is already removed at the corrugator, use the net width that reaches the converting stage.
Can I use it for other box styles?
It is built for RSC. Full overlap, half slotted and die cut styles use different panel layouts, so use the result only as a rough check for those.
If you want trim waste and board cost computed automatically from item masters and routings in your ERP, we can build that integration.
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