# Customer Bank Build Stock Calculator

> Source: https://netray.co/tools/customer-bank-build-stock-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Size a finished goods bank requested by the customer, then see the extra run hours, calendar days to build it and the cost of holding it.

## Category

supply-chain

## Industry

Automotive

## Audience

- Production planner
- Program manager
- Plant manager

## Tool

**Kind:** calculator

**Currency:** $

**Inputs:**

#### Bank requested

**Key:** bank_days

**Type:** slider

**Default:** 10

**Min:** 0

**Max:** 40

**Step:** 1

**Unit:** days of supply

#### Customer daily demand

**Key:** daily

**Type:** number

**Default:** 1800

**Min:** 0

**Step:** 50

**Unit:** pcs/day

#### Line rate at 100 percent

**Key:** rate

**Type:** number

**Default:** 140

**Min:** 1

**Step:** 5

**Unit:** pcs/hr

#### Expected OEE

**Key:** oee

**Type:** slider

**Default:** 75

**Min:** 30

**Max:** 95

**Step:** 1

**Unit:** %

#### Spare hours per day for bank build

**Key:** spare

**Type:** number

**Default:** 4

**Min:** 0.5

**Step:** 0.5

**Unit:** h/day

**Help:** Hours not needed for normal production.

#### Standard cost per piece

**Key:** unit_cost

**Type:** number

**Default:** 11.2

**Min:** 0

**Step:** 0.1

**Unit:** $/pc

#### Annual carrying cost rate

**Key:** carry

**Type:** slider

**Default:** 18

**Min:** 0

**Max:** 40

**Step:** 1

**Unit:** %

#### Months the bank is held

**Key:** hold

**Type:** number

**Default:** 4

**Min:** 0

**Step:** 0.5

**Unit:** months

**Outputs:**

#### Bank quantity

**Key:** bank_qty

**Expr:** bank_days * daily

**Format:** integer

**Primary:** true

#### Effective good parts per hour

**Key:** good_rate

**Expr:** rate * oee / 100

**Format:** decimal

#### Extra run hours to build the bank

**Key:** run_h

**Expr:** if(gt(good_rate, 0), bank_qty / good_rate, 0)

**Format:** hours

**Primary:** true

#### Calendar days to build

**Key:** cal_days

**Expr:** if(gt(spare, 0), run_h / spare, 0)

**Format:** days

#### Inventory value of the bank

**Key:** value

**Expr:** bank_qty * unit_cost

**Format:** currency

#### Carrying cost during hold

**Key:** carry_cost

**Expr:** value * carry / 100 * hold / 12

**Format:** currency

**Chart:**

#### Extra run hours vs bank days

**Type:** line

**X:** bank_days

**From:** 0

**To:** 40

**Steps:** 21

**Series:**

- run_h

**Disclaimer:** Excludes storage space cost, obsolescence risk and any customer funding of the bank.

## Content

**Intro:** Before a tool transfer, plant move or planned shutdown, customers often ask suppliers to build a bank of finished parts. This calculator shows what that request costs in run hours, calendar time and carrying cost, before you accept it.

**Sections:**

#### How to use it

**Body:** Enter the days of supply the customer wants and their daily demand from the latest release. Add the rated line speed and expected OEE, then the spare hours per day you can dedicate without hurting normal output. The result is the bank quantity and the time needed to produce it.

**Bullets:**

- Use the customer's latest release, not the nomination volume
- Spare hours are those left after normal production
- Run the chart to compare 5, 10 and 20 days

#### Formula

**Body:** Bank quantity equals days of supply times daily demand. Effective good parts per hour equals rated rate times OEE. Extra hours equals bank quantity over that effective rate. Calendar days equals extra hours over spare hours per day. Carrying cost equals inventory value times annual rate times months held over twelve.

#### Reading the result

**Body:** If calendar days to build exceed the time before the event, you need overtime, a weekend shift or a smaller bank. Compare the carrying cost with the expedite cost you avoid if the transfer slips. Agree who pays for the bank in writing, because it can tie up working capital for months and may become obsolete if the program changes.

#### Common mistakes

**Body:** Planners often use 100 percent OEE or forget that parts built early age in storage and may need re-inspection or re-preservation. Another mistake is building the bank from a single material lot, which can hide traceability issues. Align bank labeling and lot control with the customer before starting.

**Cta:** Netray can help model bank builds against open orders, material availability and capacity in your ERP so the plan is checked before the commitment is made.

**Faq:**

#### How many days of bank do customers ask for?

**Answer:** It varies widely with risk. Short transfers may ask for a week or two, while complex tooling moves may ask for several weeks. Use the customer's written requirement and your own risk assessment.

#### Who pays for the bank?

**Answer:** That is a commercial term. Some customers fund the inventory or buy it early, others expect the supplier to carry it. Settle payment and ownership before building to avoid disputes.

#### Does the bank change my OEE?

**Answer:** Not by itself, but extra running can raise utilization and reveal constraints. Use realistic OEE for the added hours and watch changeover and tool wear.

#### Can I use it for a seasonal build?

**Answer:** Yes. Treat the seasonal peak above normal output as the bank and set days of supply to the extra demand over the build window.

## Search terms

bank build calculator, safety bank inventory automotive, pre build stock for tool transfer, launch bank inventory, finished goods bank days of supply, build ahead plan calculator, tooling transfer bank requirement

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