Costing
How to cost a corrugated box
The formula Indian box plants actually use, worked end to end on a 400 × 300 × 250 mm three-ply B-flute carton.
The short answer. Cost a corrugated box in five steps: work out the blank area in square metres, work out the board GSM including the flute take-up factor, multiply the two to get sheet weight, multiply weight by your reel rate and add wastage, then add conversion cost, overhead and margin.
Step 1 — Blank size
For a regular slotted container (FEFCO 0201, the standard shipper), the flat blank before folding is:
- Blank length = 2 × (L + W) + glue lap. The lap is normally 30–40 mm depending on whether the joint is stitched, glued or taped.
- Blank width = H + W. The top and bottom flaps are each half the box width, so together they add exactly one width.
For a 400 × 300 × 250 mm box with a 35 mm lap:
Step 2 — Board GSM, with take-up
Board GSM is not just the sum of the papers. The fluting medium is corrugated, so a metre of finished board eats more than a metre of medium. That multiplier is the take-up factor, and it is set by the flute profile:
| Flute | Height (approx.) | Take-up factor | Typical use |
|---|---|---|---|
| A | 4.7 mm | 1.54 | Cushioning, light contents |
| C | 3.6 mm | 1.45 | General shipping cartons |
| B | 2.5 mm | 1.36 | Stiff, printable, stackable |
| E | 1.5 mm | 1.27 | Retail and e-commerce mailers |
For a three-ply B-flute built from a 150 GSM top liner, a 120 GSM medium and a 150 GSM bottom liner:
Step 3 — Sheet weight
Step 4 — Paper cost and wastage
At an indicative reel rate of ₹38 per kg, and a measured plant wastage of 10 percent:
| Line | Working | Amount |
|---|---|---|
| Paper | 0.366 × 38 | ₹13.89 |
| Wastage at 10% | × 1.10 | ₹15.28 |
| Conversion at ₹9/kg | 0.366 × 9 | ₹3.29 |
| Works cost | 15.28 + 3.29 | ₹18.57 |
| Overhead and margin at 18% | × 1.18 | ₹21.91 |
Ex-works price: about ₹21.90 a box. Conversion covers corrugation, printing, slotting, creasing and pasting or stitching. Plants that quote conversion per kilogram of board rather than per box find it far easier to reprice when paper moves.
Step 5 — GST on top
Finished corrugated boxes under HSN 48191010 moved to the 5 percent slab with effect from 22 September 2025, while kraft paper, starch and ink inputs remain at 18 percent. So ₹21.90 ex-works invoices at about ₹23.00 — and leaves you with input credit you cannot fully set off. That is covered on the GST page. Confirm the current rate with your CA before you invoice.
Five mistakes that turn a profitable quote into a loss
- Costing on theoretical board weight. The calculation above gives 366 g. Weigh fifty finished boxes off the line and divide. If the real figure is 395 g, every quote you have made this year is 8 percent light.
- Ignoring deckle loss. A 1435 mm blank cut from a 1600 mm reel throws away 165 mm — 10.3 percent of the paper, before a single sheet is rejected. Deckle planning across jobs is usually worth more than any discount you will negotiate on paper.
- Using a plant-wide wastage figure. A four-colour job with a tight register has nothing in common with a plain brown shipper. Wastage measured per job, per stage, is the only version that prices correctly.
- Stale reel rates. Kraft moves. A quote built on last quarter's rate is a quote built on a number that no longer exists.
- Forgetting the inverted duty gap. Output at 5 percent and inputs at 18 percent means credit accumulating in the ledger instead of cash in the bank. That is a working capital cost and it belongs in your overhead number.
Common questions
- What is the formula to cost a corrugated box?
- Blank area × board GSM ÷ 1000 gives sheet weight in kilograms. Multiply by reel rate, add wastage, add conversion cost, then add overhead and margin.
- How do I calculate board GSM for a five-ply box?
- Same method, more layers: top liner + (medium 1 × its take-up) + centre liner + (medium 2 × its take-up) + bottom liner. A BC-flute five-ply uses 1.36 for the B layer and 1.45 for the C layer.
- What wastage percentage should I use?
- Use your own, measured per stage. Indian plants commonly run 8 to 15 percent in total. The trade press figure for the average plant sits around 14 to 15 percent, and most owners have never measured their own.
- Is there a free calculator for this?
- Yes. boxcalc.theingredientlist.co runs the whole calculation above — blank size, take-up, weight, wastage and price. Free, no sign-up.
Rates and factors on this page are indicative and current as of October 2026. Take-up factors vary slightly by corrugating roll profile; confirm yours against your own board. Published by Threxa, Bengaluru — we build ERP software for corrugated box plants.