Factory Downtime Cost Calculator
Before you book a shutdown for an expansion tie-in or a retrofit, put a number on what the stop costs. Enter what the line would have made, what each unit earns over its variable cost, how long production stops, how much of it you will make up later and what the restart adds.
What this tool estimates
The contribution a planned or unplanned stop loses after the output you make up later, plus the restart and extra labour costs it adds — each on its own line, never using revenue as the loss.
What it cannot decide
- Your contribution per unit — it comes from your own costing.
- How long the stop will really last, or how much output you can really make up.
- The cost of lost customers, contract penalties or late-delivery charges.
- Fixed costs (salaried staff, rent, depreciation) — they are paid whether the line runs or not, so they are not counted.
- An insurance or legal claim value.
Result
Your contribution per unit is negative: each unit made loses money before fixed costs, so the output not made reduces that loss. The result is shown as it is, not rounded up to zero.
| Step | Value |
|---|
| Production hours lost | Made up later | Cost of the stop |
|---|
Method version 6 October 2026. A screening estimate, not a design: see the limits below.
How this calculator works — and where it stops
What it calculates
What a production stop costs in contribution — the margin over variable cost that the output not made would have earned — after the share made up later, plus the restart and extra labour costs the stop adds. The sales value of the output not made is shown only on request, as a labelled reference figure.
Inputs
- Output the line would have made, in units per hour, at the rate it would really have run.
- Contribution per unit, ₹ — selling price less the variable cost of making the unit.
- Production hours lost — hours the line would have run, not calendar hours.
- Share of the lost output made up later (overtime, other lines, stock), 0–100%.
- Restart cost, ₹ — scrap, purging, re-qualification and restart energy for this stop.
- Extra labour cost, ₹ — overtime, recovery shifts or standby crews paid only because of the stop.
- Optional: selling price per unit, used only to show the sales value of the output not made.
Method
- Output not made = output per hour × production hours lost.
- Contribution of that output = output not made × contribution per unit.
- Made up later = that contribution × the share recovered; contribution lost = the rest.
- Cost of the stop = contribution lost + restart cost + extra labour cost.
- Per production hour lost = output per hour × contribution per unit × (1 − share recovered) — the part that grows with the length of the stop. The restart cost comes once per stop.
- On request only: sales value of the output not made = output not made × selling price, shown beside the variable cost the stop did not spend. It is never added to the cost.
- Sensitivity: the cost at half and one-and-a-half times the hours lost, and with the share made up 25 points lower and higher (kept within 0–100%).
Assumptions
- Contribution per unit is constant through the stop and the recovery, and comes from the user's costing.
- Fixed costs — salaried staff, rent, depreciation, insurance — are paid whether the line runs or not, so they are not a cost of the stop.
- Output made up later earns the same contribution as the output lost; any premium paid to make it up (overtime, extra shifts, faster freight) belongs in the extra labour or restart cost.
- A negative contribution per unit is accepted and shown as it is: the stop then reduces a loss.
Limitations
- Does not value lost customers, contract penalties, late-delivery charges or reputation.
- Does not estimate how long the stop will last or how much output can really be made up — both are the user's estimates.
- Never uses revenue as the loss: the sales value appears only as a reference figure, on request.
- Not an insurance or legal claim calculation.
Worked example
Produced by running this calculator with the inputs below.
Inputs
- Output 100 units an hour
- Contribution ₹200 per unit
- 8 production hours lost
- 25% of the lost output made up later
- Restart cost ₹10,000
- Extra labour cost ₹0
Working
- Output not made = 100 × 8 = 800 units.
- Contribution of that output = 800 × ₹200 = ₹1,60,000.
- Made up later = 25% of ₹1,60,000 = ₹40,000, so the contribution lost is ₹1,20,000 (100 × ₹200 × 8 × 0.75).
- Cost of the stop = ₹1,20,000 + ₹10,000 restart + ₹0 extra labour = ₹1,30,000.
- Per production hour lost = 100 × ₹200 × 0.75 = ₹15,000.
Result. ₹1,30,000 (₹1.3 lakh) for the stop: ₹1,20,000 of contribution lost and ₹10,000 of restart cost.
Sensitivity — what moves the answer
- Hours drive the cost in a straight line apart from the one-off restart: the same stop costs ₹70,000 at 4 hours and ₹1,90,000 at 12 hours.
- The share made up matters as much as the length: with nothing made up the 8-hour stop costs ₹1,70,000; with half made up, ₹90,000.
- Splitting one long stop into two short ones leaves the contribution lost unchanged but adds a second restart cost.
How engineers use the result
To compare shutdown options for an expansion tie-in or a retrofit — one long stop against phased short stops, a holiday window against a weekday, a temporary supply against a full stop — on the same contribution basis, so the cost of a temporary arrangement can be set against the stop it avoids.
When a professional design must replace it
Before a shutdown window is agreed: production planning should confirm the output rate and the recovery really available, finance the contribution per unit, and the engineering team the length of the stop from a method statement for each tie-in.
Sources
- Contribution = selling price − variable cost per unit — standard cost-accounting definition; no external rate or benchmark is applied
Questions people ask before using it
What do I need before calculating a downtime cost?
The output the line would have made per hour during the stop, the contribution per unit from your costing (selling price less the variable cost of making it — materials, energy, consumables, piece-rate labour), the production hours the stop takes out, an honest estimate of how much of that output you can make up later, and the costs the stop adds: restart scrap and purging, re-qualification, overtime and recovery shifts.
Which site conditions could change the downtime cost?
A tie-in that overruns because the existing services are not as drawn, a test that fails and has to be repeated, a restart that takes longer than planned to reach saleable quality, recovery capacity that is not really there (other lines already full, no stock buffer), shift patterns that make a holiday window cheaper than a weekday one, and seasonal demand that turns lost output into lost orders.
What should I send an engineer to review a shutdown plan?
The existing and proposed loads, the layout of the area the work touches, and the production constraints: which lines must keep running, which windows are available and how much stock you can build beforehand. An engineer can then look for ways to shorten or split the stop — temporary supplies, prefabrication, tie-ins done in phases — and check each option against the cost this page gives.
Optional: ask an engineer to look at it
The result above is yours with no form. If you want an engineer to check it against your drawings, schedules or bills, send a request. Nothing is sent until you press the button.
Request saved
It reached our team with exactly what the preview showed. An engineer will use the number you gave if they need your drawings or data.
Prefer to talk? WhatsApp or the contact form.
Got your number — what next?
A calculator gives you a first figure. These take it further.