Manufacturing Cost Calculator — Bill of Materials, Labor and Batch Costing

Cost any product from a materials library: pack pricing, scrap, price breaks, sub-assemblies, labor, overhead, batch curves and quotes. Runs in your browser.

What it does

The Manufacturing Cost Calculator works out what one unit of a product really costs to make. You build a library of the materials you buy, describe each product as a bill of materials (BOM), add labor, machine time and overhead, and the tool returns the cost per unit and per batch, a breakdown of where the money goes, and the wholesale and retail prices that hit your margin.

It’s built for small manufacturers, makers and workshops: candle makers, food producers, sewers, print shops, electronics assemblers and anyone who buys materials in packs and sells finished goods. Everything is saved in your browser and works without an account.

How it works

Materials are entered the way you buy them. Type the pack size and pack price, for example 25 kg for 61.00, and the tool works out the price per unit. A product can then use that material in any compatible unit: grams, ounces or pounds of the same ingredient, millilitres or fluid ounces of a liquid, metres or feet of trim. The converter covers mass, volume, length, area and counted units, and it refuses to mix families, such as weight and volume, instead of guessing.

Scrap and price breaks change the real cost. Each BOM line has a scrap percentage, the share of purchased material that ends up wasted, so 10% scrap means buying one-ninth more than the product contains. Each material can have volume price breaks such as 10:4.50, 50:4.00, meaning 10 or more packs cost 4.50 each. Breaks are applied to the packs you actually need at your batch size, added up across the whole product tree, so the same material used in two places counts once toward the tier.

Sub-assemblies nest. A product can contain other products, such as a gift set made of three candles plus a box. The tool costs the inner product at the quantity the outer batch requires, so setup time and price breaks are recalculated for that quantity. It detects circular references (a product that ends up containing itself) and reports them rather than looping.

Labor, machines and overhead are separate lines. Labor and machine time are minutes per unit at an hourly rate. Setup time is a per-batch cost divided across the batch, which is why small runs cost more per unit. Overhead can be a percentage of direct cost, a percentage of labor, a fixed amount per unit, or a rate per machine hour.

Analysis tools use the same engine. The batch-size curve reruns the full costing at each quantity you choose. The cost-driver table ranks what drives the cost with cumulative shares. The what-if sliders shift all material prices and labor rates by a percentage to show the effect on unit cost. Snapshots save today’s cost so you can compare it after a supplier changes prices, and each material keeps a price history.

How to use it

1. On the Materials tab, add what you buy: name, unit, pack size, pack price, optional price breaks and supplier. Or import a CSV, or press Load the example on the Products tab to see a worked candle-and-gift-set example.
2. On the Products tab, create a product, set the batch size, and add BOM lines. Choose a material or a sub-assembly, the quantity for one unit, the unit and the scrap percentage.
3. Enter labor minutes and rate, any machine time, setup time per batch and how you allocate overhead.
4. Read the result: cost per unit, batch total, the cost breakdown bar and the wholesale and retail prices for your target margin.
5. On Analysis, drag the sliders, compare batch sizes and save a snapshot before a price change.
6. On Quote, enter the number of units to make. You get the total cost, wholesale and retail totals, and a shopping list in whole packs with left-overs and the cash needed at the till.
7. On Data, export a JSON backup of your whole library, or download materials or a bill of materials as CSV, or a PDF cost sheet.

If your supplier’s price list arrives as a messy spreadsheet, tidy it first with the CSV cleaner and import the result. If a supplier quotes in units you don’t use, the unit converter is handy for checking the conversion. Once you know your unit cost and price, the break-even calculator shows how many units cover your fixed costs, and the invoice generator turns a quote into a document you can send.

Privacy and saved data

Your library never leaves your device. Materials, products, snapshots and price history are stored in this browser, and any file you import is kept alongside them so it survives a refresh. Clearing your browser data erases them, so export a JSON backup from the Data tab regularly; the tool reminds you when you haven’t. Clear all saved data removes everything from a shared computer. The PDF export downloads a small open-source PDF library the first time you use it; none of your data is sent. Importing a JSON library replaces your current one after a confirmation, while importing a materials CSV merges by name and extends the price history of materials it updates.

Limitations

• Costs are estimates based on what you enter. They don’t include tax, freight on purchases, or currency conversion unless you add those to your prices.
• Batch pricing assumes you can buy the exact number of whole packs the batch needs.
• One currency symbol applies to the whole library.
• The PDF cost sheet uses standard PDF fonts, so characters outside basic Latin appear as question marks in the PDF only.

FAQ

How do I cost a material I buy by the pack but use by the gram?

Enter the pack as you buy it, for example unit kg, pack size 10, pack price 42. In the BOM line pick the unit g and type how many grams go into one product. The tool converts and prices it. No manual division needed.

What does scrap or yield percentage mean here?

It’s the share of the material you buy that is wasted. With 10% scrap you must purchase one-ninth more than the finished product contains, so the material cost rises by that factor. This is more accurate than adding 10% to the quantity.

How are volume price breaks applied?

The tool totals how much of each material the whole batch needs, including scrap and every sub-assembly, rounds up to whole packs, and applies the best break that quantity qualifies for. Cost per unit then uses that price, so larger batches cost less per unit when a break applies.

What’s the difference between markup and margin?

Margin is profit as a share of the selling price. Markup is profit as a share of cost. A 40% margin equals a 66.7% markup. The tool shows both for wholesale and retail so you can compare them with supplier and competitor figures.

Can I move my library to another computer?

Yes. Export the library as JSON from the Data tab and import it in another browser. Importing replaces the library after you confirm.

Are my recipes and costs private?

Yes. Nothing is uploaded, and the tool needs no account. The only time a file leaves the page is when you download an export yourself.