Cost rates — overview

The app calls this catalogue Cost rates, and each row in it a cost rateCost rateA reusable priced input attached to a bill, such as labour, electricity, machine time or an overhead allocation. Each cost rate is one entry in a shared catalogue, with a name, a kind (labour or overhead), a unit and a money-per-unit rate. The quantity consumed multiplied by that rate gives the additional costs for that line. Read more → : a per-unit cost that isn’t a material, such as dipping labour, electricity, machine time or a cleaning cycle. You define the rate once in the shared catalogue, then attach it to a bill of materialsBill of materialsA bill of materials tells Assemblified how to build one unit of a finished good. When a customer orders the finished-good variant, Assemblified deducts the right component quantities from inventory automatically. Read more → or an assembly BOMAssembly BOMThe BOM for an intermediate component you build and then use inside other bills — a lid, a wick assembly, a pre-wired harness. It keeps its own pre-assembled stock and can be a work order item in its own right. Read more → (the component it defines is a subassembly) with the quantity consumed per one finished unit.

line cost = quantity × rate

There is no waste multiplier — waste is a materials concept. Twenty minutes of operator time doesn’t get “wasted” the way wax does.

On this page

• Why it exists
• The two rules
• Labour vs. overhead
• Where cost rates show up

Why it exists

Before cost rates, labour lived only on a work orderWork orderA planned production run: pick materials, build the items, do QC, and complete — all tracked together. Use work orders when you're building stock ahead of demand or running a multi-day project. Read more → and never reached the BOM’s cost. For a candle that gets dipped ten times, labour and electricity are the majority of what the candle actually costs to make. The only workaround was folding process cost into some material’s unit cost — which corrupts that material everywhere else it’s used.

The two rules

Everything else on these pages follows from two rules. They differ on purpose.

1. On a bill, cost is always live

Change a rate once, and every bill that references it re-prices immediately. Nothing is cached, so nothing can go stale. Attaching a cost rate and removing one take effect the moment you do it; a change to an attached cost rate’s quantity is an edit to the bill like any other and goes out when you save the page.

2. On a work order, the rate is frozen — but the quantity is not

When you create a work order, each item captures the rate it saw at that moment. Editing the cost rate’s rate afterwards, or attaching a new cost rate to the BOM, will never move that work order’s costs. But changing how many units you’re building will: twenty candles cost twice the electricity of ten.

Note

That asymmetry is the whole point. A BOM answers “what does this cost to make today?” — it should follow today’s rates. A work order is a record of a job you priced at a moment in time — it should not silently re-price itself behind you.

Labour vs. overhead

Every cost rate has a Kind, and you pick it when you create the cost rate:

Kind	What it means	Where it lands on a work order
Labour	Human time	The work order’s Labour cost card
Overhead	Everything else — power, machine time, consumable process cost	The work order’s Additional cost card

Never both. A Labour-kind cost rate is not counted a second time as overhead, which is what makes it safe to tick both checkboxes when you push a cost to Shopify.

On a bill of materials or assembly BOM, the distinction doesn’t change the arithmetic — both kinds roll into the same Additional costs per unit figure, because that number is the bill’s full cost to make. Kind only decides which of the work order’s two cost cards files it under.

Where cost rates show up

Settings → Catalogues → Cost rates Create a cost rate, set its rate, see what's using it. Needs the Enhanced plan.

On a bill of materials or assembly BOM Attach a cost rate with a per-unit quantity on the Materials tab; read it back in the Financial breakdown.

On a work order Frozen rates, rescaling quantities, and the labour hand-over.

Pushing cost to Shopify Two opt-in checkboxes, both off by default.

Worked example

The candle-dipping sheet this feature was built from — a dip add-on applied to a plain candle:

Component	Qty per candle	Rate	Line cost
White dinner candle (material)	1	landed cost	—
Dip wax (virtual materialVirtual materialA material tracked entirely inside Assemblified — not a Shopify variant. Useful for shop-floor consumables (glue, packaging, labour units) where you need quantity tracking but don't want a Shopify product on your storefront. Read more → , g)	263.6 g	$0.0033 / g	$0.869880
Dipping labour (Labour cost rate, hour)	0.0166667 h	$40 / h	$0.666668
Electricity (Overhead cost rate, kWh)	0.1 kWh	$0.4163 / kWh	$0.041630
Dip add-on total			$1.578178

Note the labour quantity: one minute is 0.0166667 hours, not 0.0167. Quantities are fractional and kept exactly as you type them — enter the real number, not a rounded display value.

See also

• Track building cost — the older virtual work-hour pattern, and when it’s still the right tool.
• Check BOM margin and cost breakdown — reading the rolled-up cost.