How to calculate job cost for a manufacturing job
Job cost is the sum of material issued to the job at its real issue cost, labour hours booked to the job multiplied by the work-centre rate, and any outside processing or subcontract charges. Add a share of overhead if you recover overhead through jobs. Divide the total by the good quantity produced to get cost per unit.
By Arunkumar V, CTO · 03 November 2026 · 2 min read
- how to calculate job cost
- job costing formula
- job cost sheet
- manufacturing job cost example
The job cost formula in words
Job cost has three parts every shop can measure and one that is optional. Material is what the store actually issued to the job, valued at the cost on the issue movement, less anything returned. Labour is the hours booked at each work centre multiplied by that work centre's rate. Outside processing is whatever a subcontractor billed for plating, heat treatment or painting on that job. Overhead is a share of rent, power and supervision, usually a percentage of labour.
As one line: job cost = material at issue cost + labour hours × work-centre rate + outside processing (+ overhead share). Cost per unit = job cost ÷ good quantity. Scrapped units stay in the cost but not in the good quantity.
A worked example with sample numbers
The figures below are invented to show the arithmetic. Say a job for 50 brackets issues 12.6 kg of sheet at 78 per kg (982.80), 200 M6 fasteners at 1.20 each (240.00) and 1 kg of powder coat at 310 (310.00). Material comes to 1,532.80. The job books 3.5 hours on the laser at 900 per hour (3,150.00) and 2 hours on the press brake at 600 per hour (1,200.00), so labour is 4,350.00. Plating goes out and the vendor bills 850.00.
Job cost is 1,532.80 + 4,350.00 + 850.00 = 6,732.80. Two brackets failed inspection, so 48 are good. Cost per unit is 6,732.80 ÷ 48 = 140.27.
Mistakes that distort job cost
Most wrong job costs come from the data feeding the formula, not from the formula. Cost the job on the day it closes, once the last issue, return, time entry and vendor bill are in, and check for these.
- Valuing material at the standard or last quoted price instead of the cost on the issue movement.
- Not booking returns, so unused sheet stays on the job and the next job looks too cheap.
- Leaving rework hours off the job or booking them to a general account.
- Closing the job before the subcontract bill arrives, so outside processing reads as zero.
- Counting scrapped parts as good quantity, which hides the real cost per unit.
How to calculate the cost of a job
- Step 1
Open the work order and list every material issue and return with the quantity and the cost on each movement.
- Step 2
Add the labour hours booked at each work centre and multiply each by that work centre's rate.
- Step 3
Add every subcontract or outside processing bill matched to this job.
- Step 4
Add an overhead share if your shop recovers overhead through jobs, using the same rule on every job.
- Step 5
Add the parts together for total job cost, then divide by the good quantity for cost per unit.
Where ZMOS fits
ZMOS costs each work order on the day it closes: material at the real cost on each issue movement plus labour at the work-centre rate, per job and per unit. Job work (subcontracting) is supported, so outside processing lands on the job. It suits sheet-metal, machining and fabrication shops of 10 to 50 people that run discrete jobs. If you run a continuous process with no job boundaries, or only want a quoting calculator, a job-costing ERP is more than you need. See job costing in ZMOS.
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Inside ZMOS
Should job cost use the purchase price or the issue cost of material?
Use the cost on the issue movement. Purchase prices change between deliveries, and the sheet issued today may have been bought last month. An issue cost from the stock ledger reflects what that material actually cost the shop.
How do I include overhead in job cost?
Pick one method and apply it to every job: a percentage uplift on labour cost, or an overhead amount built into each work-centre hourly rate. Consistency matters more than precision, because you compare jobs with each other.
What rate should I use for labour?
Use a work-centre rate: the running cost of that machine and its operator per productive hour. One blended rate for the whole shop makes machine-heavy jobs look cheaper than they are and bench work dearer.
How is job costing different from process costing?
Job costing collects cost per job or batch, which suits shops making different parts to order. Process costing spreads cost over all units made in a period, which suits continuous production of one product. Most job shops need job costing.
See it on your own stock and jobs
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