Inventory
Bill of Materials (BOM) Format: Examples for Manufacturers
A bill of materials format for small manufacturers: the columns, a worked plastic bucket BOM with scrap allowance, material costing and common mistakes.
In short
A bill of materials (BOM) lists every material, part and packing item needed to make one unit of a product, with the quantity, unit, scrap allowance and rate for each line. Multiply each net quantity by (1 + scrap %) to get the gross quantity, multiply by the rate, and the sum is the material cost per unit.
- A usable BOM has, for each line: item code, description, quantity per unit, unit, scrap or wastage %, gross quantity, rate and line cost.
- Gross quantity = net quantity × (1 + scrap %). The scrap allowance is what keeps the store from running short mid-batch.
- Packing materials such as polybags, cartons and labels belong in the BOM; leaving them out understates cost and causes shortages.
- A single-level BOM lists raw materials only; a multi-level BOM adds sub-assemblies that have their own BOMs.
- Material cost per unit is not the full cost of production; labour, power and overheads come on top.
What a bill of materials is
A bill of materials (BOM) is the recipe for one unit of a product. It lists every raw material, bought-out part and packing item that goes into it, and how much of each.
For a small manufacturer, a BOM does three jobs:
- Purchase planning. Multiply the BOM by the order quantity and you know what to buy.
- Store issue. The store knows what to hand to the shop floor for each batch.
- Costing. Multiply each line by its rate and you know the material cost per unit.
Most small factories keep this knowledge in the owner’s head or a supervisor’s notebook. Writing it down in a fixed BOM format is the first step to quoting accurately and catching material leakage.
The columns of a BOM format
Header
| Field | Example |
|---|---|
| Finished item | Plastic bucket 10 L, red |
| BOM code | BOM-BKT10-R |
| Version | 1.0 |
| Effective from | 01-10-2026 |
| Base quantity | 1 piece |
| Prepared / approved by | Production head / owner |
The version and effective date matter. When the mould changes or you switch granule grade, you make version 1.1 rather than editing 1.0, so old costings still make sense.
Lines
| Column | What it holds |
|---|---|
| Line no. | 1, 2, 3 |
| Item code | Your material code |
| Description | PP granules, master batch, handle |
| Type | Raw material, bought-out part, packing |
| Net quantity per unit | What actually ends up in one piece |
| Unit | kg, g, pcs, m |
| Scrap / wastage % | Allowance for start-up, rejects and losses |
| Gross quantity | Net × (1 + scrap %) |
| Rate | Current purchase rate per unit |
| Line cost | Gross quantity × rate |
| Remarks | Supplier, grade, alternate material |
Keep units consistent. If granules are bought in kg, write the BOM in kg (0.420 kg), not grams (420 g). Mixing units is the most common cause of a BOM that is wrong by a factor of 1,000.
Worked example: single-level BOM for a plastic bucket
A 10-litre injection-moulded bucket with a metal wire handle, packed one per polybag and 20 per carton. The figures are illustrative; use your own weights and rates.
| # | Material | Type | Net qty | Unit | Scrap % | Gross qty | Rate (₹) | Cost (₹) |
|---|---|---|---|---|---|---|---|---|
| 1 | PP granules | Raw material | 0.420 | kg | 3% | 0.4326 | 110.00 / kg | 47.59 |
| 2 | Master batch, red | Raw material | 0.0084 | kg | 3% | 0.00865 | 250.00 / kg | 2.16 |
| 3 | Wire handle | Bought-out | 1 | pcs | 1% | 1.01 | 6.00 / pc | 6.06 |
| 4 | Polybag | Packing | 1 | pcs | 0% | 1.00 | 1.50 / pc | 1.50 |
| 5 | Carton (20 buckets) | Packing | 0.05 | pcs | 0% | 0.05 | 40.00 / pc | 2.00 |
| 6 | Label sticker | Packing | 1 | pcs | 2% | 1.02 | 0.50 / pc | 0.51 |
| Material cost per bucket | 59.82 |
How the numbers were reached:
- Granules: the moulded bucket weighs 420 g. With a 3% allowance for start-up shots and rejects, 0.420 × 1.03 = 0.4326 kg. At ₹110 per kg, that is ₹47.59.
- Master batch: dosed at 2% of the polymer weight, so 0.420 × 0.02 = 0.0084 kg, plus 3% scrap.
- Carton: one carton holds 20 buckets, so each bucket uses 1 ÷ 20 = 0.05 carton.
Scaling to a batch
For an order of 1,000 buckets, multiply each gross quantity by 1,000:
| Material | Required for 1,000 |
|---|---|
| PP granules | 432.6 kg |
| Master batch | 8.65 kg |
| Wire handles | 1,010 pcs |
| Polybags | 1,000 pcs |
| Cartons | 50 pcs |
| Labels | 1,020 pcs |
Compare this with stock in the store before you accept a delivery date. If you have 300 kg of granules, you know today that you need to buy at least 133 kg more.
Setting the scrap allowance
Scrap percentage is a judgement, and the right number comes from your own records:
- Start-up loss: the first shots after a mould change or colour change are scrap.
- Rejects: short shots, flash, colour streaks.
- Handling loss: granules spilled, labels torn.
Start with a figure your supervisor trusts, typically a few percent for moulding, then compare with actual consumption after ten batches. If you regrind runners and rejects back into production, your net loss is lower than your reject rate; set the allowance on the net loss.
Too low, and the store runs short mid-batch. Too high, and your costing hides waste that someone should be asking about.
Costing a BOM: material cost per unit
The sum of line costs is the material cost per unit: ₹59.82 in the example. It is the largest part of the cost for most small manufacturers, but it is not the whole cost.
| Cost element | In the BOM? |
|---|---|
| Raw materials, bought-out parts, packing | Yes |
| Machine time, power | No |
| Labour | No |
| Factory overheads, rent, depreciation | No |
| Freight out, sales commission | No |
If your selling price is ₹95 and material is ₹59.82, the ₹35.18 left must cover everything in the “No” rows and your profit. Track the material share when granule prices move: a ₹10 per kg rise in PP adds about ₹4.33 per bucket (0.4326 kg × ₹10).
Single-level and multi-level BOMs
A single-level BOM lists raw materials and bought-out parts directly under the finished item, as in the bucket example.
A multi-level BOM applies when you make some parts yourself. Suppose you mould a plastic grip and fit it onto the wire handle in-house:
- Level 0: Bucket 10 L
- Level 1: Handle assembly (made in-house)
- Level 2: Wire, 0.35 m
- Level 2: PP granules for the grip, 0.012 kg
- Level 1: PP granules for the body, 0.420 kg
- Level 1: Packing items
- Level 1: Handle assembly (made in-house)
The handle assembly gets its own BOM. You produce handles first, put them into stock, then issue them to bucket production. For most small factories, two levels are plenty.
How the BOM connects to production
The BOM is the master. The documents that use it change with every batch:
| Document | What it says | When |
|---|---|---|
| Bill of materials | What one unit needs | Once per product, revised by version |
| Production plan | How many units, by when | Weekly or per customer order |
| Production order | This batch: target quantity, materials required | Per batch |
| Material issue | What the store actually handed over | When the batch starts |
| Job card | Good quantity, rejects, material consumed, scrap | Per shift or per run |
The useful number comes from comparing the first row with the last. If the BOM says 432.6 kg of granules for 1,000 buckets and the job cards show 455 kg consumed for 1,000 good pieces, there is 22.4 kg unexplained. That is about 5% more than planned, and worth a conversation with the shift supervisor.
Building your first BOM in a day
- Pick your best-selling product. One accurate BOM is worth more than ten guesses.
- Weigh the finished piece on a calibrated scale, three pieces, and take the average.
- List every bought item by walking the product from the moulding machine to the dispatch bay, including tape, labels and cartons.
- Ask the supervisor for the scrap figure, then write it down as a starting point, not a final answer.
- Take rates from the last purchase bills, not from memory.
- Run one batch and compare actual consumption with the BOM. Adjust and save as version 1.1.
Keep your raw material stock accurate while you do this; a stock register helps if you are still on paper.
Mistakes that make a BOM useless
- Mixed units — grams on one line, kg on the next.
- No packing lines — cartons and labels run out on dispatch day.
- No scrap allowance — every batch runs short.
- Old rates — costing at last year’s granule price.
- Editing instead of versioning — nobody knows which BOM a past batch used.
- Treating material cost as total cost — and quoting below break-even.
How VyapRise handles BOMs and production
In VyapRise, the BOM, production plans, production orders, job cards and quality checks are on the Pro plan.
- BOM: a BOM code, version and effective date for a finished item, with material lines that each carry a quantity per unit, a unit and a wastage percentage.
- Production order: pick the item and target quantity; VyapRise explodes the BOM into planned material quantities, checks availability in a chosen warehouse and shows any shortfall, then issues materials and books finished goods into stock when you complete the order.
- Job cards: record good and rejected quantity, material actually consumed and scrap weight.
- Costing: batch size, labour, machine hours and overhead % on top of material give a standard cost and margin; each production order’s cost sheet shows planned against actual material quantities and the actual cost per unit made.
- Scrap and by-products: booked into stock at a value and credited to the run’s cost.
- Sub-assemblies: a BOM can take a semi-finished item that has its own BOM, each stage gets its own job card, and work in progress is shown per stage.
- Job work: send material to a job worker on a challan, record what comes back, and download the ITC-04 file.
Read more on the manufacturing software for small business page, or see how raw materials are tracked in inventory management.
How VyapRise handles this
BOM with wastage per line (Pro)
Each BOM line in VyapRise carries a material, a quantity per unit, a unit and a wastage percentage, with a BOM code, version and effective date.
Production orders that check stock (Pro)
A production order explodes the BOM for the target quantity, checks material availability in a warehouse, issues materials and books finished goods into stock.
Job cards and full costing (Pro)
Job cards record good and rejected quantity, material consumed and scrap; costing adds labour, machine hours and overhead % to material for a standard cost and margin.
Frequently asked questions
What columns should a bill of materials format have?
At minimum: line number, item code, description, type (raw material, bought-out or packing), net quantity per unit, unit, scrap or wastage %, gross quantity, rate and line cost. The header should carry the finished item, BOM code, version, effective date and base quantity.
How do I calculate scrap allowance in a BOM?
Gross quantity = net quantity × (1 + scrap %). For 0.420 kg of granules with a 3% allowance, the gross quantity is 0.420 × 1.03 = 0.4326 kg. Set the percentage from your own consumption records and review it after a few batches.
Is BOM cost the same as cost of production?
No. A BOM gives the material cost per unit: raw materials, bought-out parts and packing. Labour, power, machine time and factory overheads come on top, so price your product on the full cost, not the BOM cost alone.
When do I need a multi-level BOM?
When you make some parts yourself and then assemble them, such as a moulded grip fitted onto a handle before the handle goes on the bucket. The sub-assembly gets its own BOM, is produced first and then issued to the final product.
Can I keep a BOM in Excel?
Yes, and many small factories start there. Excel works for costing one product. It gets hard when you need to check stock before a batch, issue materials and compare planned with actual consumption, which is where production software helps.
Does VyapRise include labour cost in production costing?
Yes. On the BOM you set a batch size, labour, machine hours and an overhead percentage, and VyapRise works out a standard cost and margin on top of the material cost. Scrap and by-products can be booked into stock at a value. BOM and production features are on the Pro plan.