Every corrugated box quotation and every job card starts with the same question: how many kilograms of each paper will this order consume? Get it wrong and the plant either runs short of a reel in the middle of a job or ties up money in paper it did not need. This guide explains, step by step, how the paper requirement of a 3-ply or 5-ply box is calculated from its inside size – outer size, deckle, cutting size, number of boards, effective GSM of the fluted layers and the weight of every layer – with a complete 5-ply worked example. To run the numbers for your own box, use our free corrugated box calculator.
The terms you need
- Ply: the number of paper layers in the board. A 3-ply board is top liner + flute + bottom liner. A 5-ply board is top liner + flute + middle liner + flute + bottom liner.
- Flute: the wave-shaped layer that gives the board its strength and thickness. Common profiles are A, B and C; a 5-ply board often combines two, for example B and C (BC).
- Take-up (flute %): the extra paper a fluted layer consumes because it is corrugated into waves. A flute with a take-up of 41% uses 1.41 metres of paper for every metre of board.
- Flute height: the thickness the flutes add to the board, which is why the outer size of a box is larger than its inside size.
- GSM and BF: grams per square metre of the paper and its bursting factor.
- Deckle (reel size): the width of paper across the corrugator, in millimetres.
- Cutting size: the length of each sheet cut from the board.
- Ups: how many boxes come out of one board.
Step 1 – Outer size from inside size
Customers specify the inside size, because that is what the product must fit into. The board adds thickness, so: OD = ID + flute height on each of length, width and height.
Step 2 – Deckle and cutting size
For a regular slotted carton (RSC), Tejaxo ERP uses these defaults in its Process Plan:
- Deckle (reel size) = ((OD width + 2 + OD height) x 2) + trim margin
- Cutting size = (OD length x 2) + (OD width x 2) + stitching flap + 5
The small allowances (+2, +5) and the trim margin cover scoring and side trim. Plants tune them to their machines, which is why they are kept as settings rather than typed into a spreadsheet each time. The deckle can never exceed the maximum reel width of the corrugator, so the machine master holds that limit.
Step 3 – Number of boards and running length
- Boards = order quantity / ups
- Total running length (m) = cutting size x boards / 1,000
Step 4 – Effective GSM of each layer
Liners are flat, so their effective GSM equals their GSM. Fluted layers consume more paper: effective GSM = GSM x (1 + flute % / 100). The sum of the effective GSM of all layers is the board GSM.
Step 5 – Weight of each layer
Layer weight (kg) = deckle (mm) x cutting size (mm) x effective GSM x boards / 1,000,000,000. The billion converts square millimetres to square metres and grams to kilograms. Add the layers and you have the paper requirement for the order; divide by the quantity for the paper weight per box.
Worked example: a 5-ply BC-flute box
Tejaxo Manufacturing receives an order from Tejaxo Customer for 1,000 boxes of Product A (sample numbers): inside size 400 x 300 x 250 mm, 5-ply, BC flute with a combined flute height of 6 mm, trim margin 20 mm, stitching flap 35 mm, 2 ups.
- Outer size: 406 x 306 x 256 mm.
- Deckle: ((306 + 2 + 256) x 2) + 20 = 1,148 mm.
- Cutting size: (406 x 2) + (306 x 2) + 35 + 5 = 1,464 mm.
- Boards: 1,000 / 2 = 500. Running length: 1,464 x 500 / 1,000 = 732 m.
| Layer | GSM | Flute % | Eff. GSM | Kg |
|---|---|---|---|---|
| Top | 140 | – | 140.0 | 117.6 |
| Flute B | 120 | 41 | 169.2 | 142.2 |
| Middle | 120 | – | 120.0 | 100.8 |
| Flute C | 120 | 48 | 177.6 | 149.2 |
| Bottom | 140 | – | 140.0 | 117.6 |
| Total | 746.8 | 627.6 |
The order needs about 628 kg of paper – roughly 0.63 kg per box – split by layer so that the store can issue the right reels. Each fluted layer weighs more than a liner of the same GSM because of take-up; forgetting that is the most common reason a corrugator runs out of flute paper before the liners.
The same box in 3-ply
If the customer accepts a 3-ply board with a single B flute (height 3 mm, take-up 41%) and the same 140 / 120 / 140 GSM papers, the outer size becomes 403 x 303 x 253 mm, the deckle 1,136 mm and the cutting size 1,452 mm. The layers then weigh 115.5 kg (top), 139.5 kg (flute B) and 115.5 kg (bottom): about 370.5 kg for 1,000 boxes, or 0.37 kg per box instead of 0.63 kg. That difference is why ply, flute and GSM must be fixed in the plan before a price is quoted.
From the paper calculation to the job card
In Tejaxo ERP for packaging this calculation lives in a Process Plan kept once for each customer and product. It holds the box style, ply, flute, ups, trim, stitching flap, inside size, the paper for every layer and specification rows such as board GSM, cut quantity, running length, box weight, bundle, joint, punching and print colours. Pressing Calculate fills the outer size, deckle, cutting size, boards and layer weights.
When a sales order arrives, the Job Card copies the plan and works out the paper request for the job quantity: request = layer weight / standard quantity x job quantity, plus the standard wastage percentage. For example, if the plan is for 1,000 boxes and the job is for 1,500 with 5% wastage, the top liner request is 117.6 / 1,000 x 1,500 = 176.4 kg plus 8.8 kg wastage = 185.2 kg. Paper is then issued from the store against the job, so the Issue vs Production report shows what each job consumed.
Common mistakes in paper calculation
- Ignoring take-up. Using the flute paper’s plain GSM under-estimates the fluted layers by 40-55%.
- Using inside size for the blank. The board’s thickness must be added, or boxes come out too small.
- A deckle wider than the machine. Check the corrugator’s maximum reel width before quoting.
- One spreadsheet per salesperson. Different allowances give different prices for the same box; keep one plan per customer and product.
- No wastage on the job. Start-up, trim and rejection need a standard wastage percentage on every job.
Next step
Share one of your box specifications and we will show the Process Plan, Job Card and paper requirement for it in Tejaxo ERP. Book a free demo, or read how production planning and inventory work for manufacturers.
Frequently asked questions
How do you calculate the paper weight of a corrugated box?
Work out the outer size (inside size + flute height), the deckle and cutting size of the sheet and the number of boards. Then for each layer, weight in kg = deckle x cutting size x effective GSM x boards / 1,000,000,000, where effective GSM = GSM x (1 + flute % / 100). Add the layers.
What is flute take-up?
The extra paper a fluted layer uses because it is corrugated into waves. A take-up of 41% means 1.41 metres of paper per metre of board, so the effective GSM of that layer is 1.41 times its GSM.
What is the difference between 3-ply and 5-ply board?
A 3-ply board has a top liner, one flute and a bottom liner. A 5-ply board has a top liner, a flute, a middle liner, a second flute and a bottom liner, which makes it stronger and thicker.
What is the deckle in corrugation?
The width of the paper across the corrugator. For a regular slotted carton it is calculated from the outer width and height of the box plus allowances and the trim margin, and it can never exceed the maximum reel width of the machine.
How is board GSM calculated?
Board GSM is the sum of the effective GSM of all layers – liners at their GSM, fluted layers at GSM x (1 + flute % / 100).
Can an ERP calculate paper requirement automatically?
Yes. In Tejaxo ERP a Process Plan per customer and product calculates the outer size, deckle, cutting size, boards and the weight of every layer, and the Job Card turns it into a paper request for the job quantity with standard wastage.