BYTETOOLS

BOM Cost Calculator

Roll up a two-level bill of materials with scrap, labour, overhead and freight to a landed unit cost, target sell price and the top cost drivers.

Bill of materials

Columns, left to right: level, part name, quantity per assembly, unit cost, scrap rate (%), unit weight (g). A level-1 row followed by level-2 rows is treated as a sub-assembly: its own unit cost is ignored and the children roll up into it instead.

Conversion cost and landed adders

$44.40
Material cost / unit
$16.40
Labour + overhead / unit
$1.80
Freight / unit
$62.61
Landed unit cost
$113.83
Sell price / unit
$51.22
Gross profit / unit
PartQtyEffective unit costScrapLine costShare of landed cost
Enclosure assemblysub-assembly1.00$9.702.0%$9.9015.8%
Main PCB1.00$18.403.0%$18.9730.3%
Li-ion cell2.00$6.751.0%$13.6421.8%
Packaging1.00$1.900.0%$1.903.0%
Material subtotal———$44.4070.9%
Top cost driversCost per unitShare of landed cost
Main PCB$19.1130.5%
Li-ion cell$14.1022.5%
Enclosure assembly$10.8317.3%
Direct labour$8.8714.2%
Overhead$7.5412.0%
Packaging$2.173.5%
$62,607
Cost for the whole build
45.0%
Achieved margin at sell price
745 g
Total BOM weight per unit

line cost = qty per assembly × unit cost ÷ (1 − scrap rate)  ·  landed cost = material + labour + overhead + freight ÷ build qty  ·  price = cost ÷ (1 − margin)

Worked example: two pieces at $5.00 each with a 5% scrap rate cost 2 × 5 ÷ 0.95 = $10.53, not $10.00 — you have to buy 1 ÷ 0.95 pieces for every good one that reaches the finished unit. Fourteen minutes of labour at $38.00 an hour is $8.87, and an 85% overhead rate on labour adds $7.54.

Scrap is applied as a yield divisor rather than a simple uplift, which is the standard treatment: a 10% scrap rate raises the cost by 11.1%, not 10%. Overhead here is a single blanket rate — if your plant uses machine-hour or activity-based rates, cost each driver separately and enter the result as labour. Freight is allocated by weight or by line value purely for the cost-driver view; the landed unit cost is the same either way. Everything is computed in your browser and nothing is uploaded. Estimates for planning, not financial advice.

What is the BOM Cost Calculator?

A bill of materials rollup turns a parts list into a number you can price against. This calculator costs every line as quantity per assembly × unit cost ÷ (1 − scrap rate), which is the standard yield treatment: a 10% scrap rate raises the cost by 11.

  • Two-level rollup where level-2 children cost their level-1 parent
  • Scrap applied as a yield divisor, the standard manufacturing treatment
  • Labour from minutes and a loaded hourly rate, plus overhead on a chosen basis
  • Freight allocated across the build and shown per unit
  • Sell price on either a margin-on-price or a markup-on-cost basis
  • Ranked cost drivers with share bars, and CSV download of the rollup

How to use the BOM Cost Calculator

  1. 1

    Add a row per part: level, name, quantity per assembly, unit cost, scrap rate and unit weight.

  2. 2

    Put level-2 rows directly beneath the level-1 row they belong to, to build a sub-assembly.

  3. 3

    Enter labour minutes per unit, the loaded hourly rate and your overhead percentage and basis.

  4. 4

    Add the freight for the whole build and the build quantity to get freight per unit.

  5. 5

    Choose a margin or markup basis and read the landed cost, sell price and top cost drivers.

About the BOM Cost Calculator

A bill of materials rollup turns a parts list into a number you can price against. This calculator costs every line as quantity per assembly × unit cost ÷ (1 − scrap rate), which is the standard yield treatment: a 10% scrap rate raises the cost by 11.1%, not 10%, because you have to buy more than you ship.

Sub-assemblies are supported: mark a row as level 1 and the rows beneath it as level 2, and the children roll up into the parent instead of its own unit cost. On top of the material total it adds direct labour from minutes and a loaded rate, a blanket overhead percentage on the basis you choose, and freight spread across the build.

The result is a landed unit cost, a target sell price on either a margin or a markup basis, and a ranked list of the cost drivers with their share. Everything is computed in your browser and nothing is uploaded. Estimates for planning, not financial advice.

Frequently asked questions

How do you calculate BOM cost with scrap?

Divide by the yield rather than adding a percentage: line cost = quantity × unit cost ÷ (1 − scrap rate). Two pieces at 5.00 each with a 5% scrap rate cost 2 × 5 ÷ 0.95 = 10.53, not 10.50, because you must buy one divided by 0.95 pieces for every good one that reaches the finished unit.

What is landed unit cost?

Everything it costs to have one finished, sellable unit in your warehouse: material after scrap, direct labour, allocated overhead and inbound freight. It is the number to price against, because a sell price set on material cost alone will quietly lose money on every unit.

How does a multi-level BOM roll up?

Child parts are costed first, their line costs sum to the sub-assembly's unit cost, and that figure is then multiplied by the parent's quantity and divided by the parent's own yield. This tool supports two levels, which covers most assembled products without turning the table into an MRP system.

Should overhead be applied to labour or to total cost?

It depends on what drives your overhead. Labour-based rates are traditional in assembly-heavy plants; material-based or total-cost rates suit operations where handling and procurement dominate. The basis is selectable here, and the difference on a material-heavy product can be large.

What is the difference between margin and markup on the sell price?

Margin is measured on the selling price, markup on the cost. A 45% margin means price = cost ÷ 0.55; a 45% markup means price = cost × 1.45. The same percentage gives very different prices, which is the single most common pricing mistake in a BOM rollup.

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