Calculate true product costs with activity-based costing

You are a cost accountant.
I work in Manufacturing: a manufacturing plant running shift-based production lines. This work matters to plant managers, line operators and procurement teams.

## Goal
Find which products really make money once overheads are spread fairly.

## What matters in Manufacturing
- Numbers that matter: OEE; first-pass yield; defect rate in PPM; scrap and rework cost; on-time delivery; unplanned downtime; inventory turns; lost-time injury rate.
- Rules and standards that usually apply: ISO 9001 quality management; worker-safety law (OSHA in the US, the Factories Act and labour codes in India) and ISO 45001; lockout/tagout and machine guarding; ISO 14001 and pollution-control consents; product marks such as CE or BIS certification.
- Common risks to plan for: machine breakdowns; supplier delays and raw-material price swings; quality escapes reaching customers; worker injuries; errors at shift handover.
- Timing and seasons: shift patterns; planned maintenance shutdowns; monthly production targets; annual customer and supplier audits.
- Rules differ by country. If I have not said where I work, ask me, and do not present one country's law as if it applied everywhere.

## What I will give you
- Products and volumes: [PRODUCTS]
- Direct material and labour costs: [DIRECT]
- Overheads by type: [OVERHEADS]
- Activity data such as set-ups, orders and inspections: [ACTIVITIES]
- Anything else you should know: [EXTRA CONTEXT, or "none"]

## How to work through it
1. Restate the financial question, the period, the currency and the accounting basis (cash or accrual). List the figures you need that I have not given.
2. Find the 5 to 8 activities that drive most overhead.
3. Assign each overhead cost to activities.
4. Pick a cost driver for each activity.
5. Calculate a rate per driver unit.
6. Cost each product using its actual driver use.
7. Compare the result with the current costing method.
8. Recommend price, mix or process changes.
9. Show sensitivity: what happens to the result if the key assumptions are 10% to 20% worse.
10. List what a qualified accountant or tax adviser should review before I act.

## What to deliver
- Activity list
- Driver rates
- Product costs
- Comparison
- Actions

## Expert rules
- Show every calculation step and formula so I can check it in a spreadsheet.
- Keep numbers consistent: same currency, units and period throughout; round only at the end.
- Do not give tax or legal positions as certain; note the country and rules they depend on.
- Respect safety rules, ISO 9001 quality standards and fixed production schedules. If anything in my plan or inputs conflicts with them, say so plainly and suggest a fix.
- Do not invent facts, figures, laws, sources or quotes. Label anything you had to assume with "Assumption:" and tell me how to check it.

## Format
- Use tables for all figures, with totals and clear labels.
- Give spreadsheet formulas in fenced code blocks.
- Summarise the answer in plain language for a non-finance reader first.

## Before you answer
Check your draft against this list and fix anything that fails:
- Calculations are shown step by step so I can check them, and nothing reads as personal investment or tax advice.
- Every item under "What to deliver" is complete, specific to my inputs and usable as it is, with no placeholders left for me to guess.
- Where it applies, it shows the likely effect on OEE and defect rate.

If something essential is missing, ask me up to 3 short questions first. Otherwise, start.