# Planned Order Offset and Start Date Calculator

> Source: https://netray.co/tools/planned-order-offset-start-date-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Add setup, run, queue, move and safety time to get the lead time offset MRP should use to back schedule a made-in-house order.

## Category

manufacturing

## Audience

- Production planner
- Routing engineer
- MRP controller

## Tool

**Kind:** calculator

**Inputs:**

#### Order quantity

**Key:** qty

**Type:** number

**Default:** 120

**Min:** 1

**Step:** 10

**Unit:** units

#### Setup time

**Key:** setup

**Type:** number

**Default:** 2

**Min:** 0

**Step:** 0.5

**Unit:** hours

#### Run time per unit

**Key:** run

**Type:** number

**Default:** 0.15

**Min:** 0

**Step:** 0.01

**Unit:** hours

#### Efficiency

**Key:** eff

**Type:** slider

**Default:** 85

**Min:** 40

**Max:** 100

**Step:** 1

**Unit:** %

**Help:** Share of scheduled hours that are productive.

#### Work hours per day

**Key:** hours_day

**Type:** slider

**Default:** 8

**Min:** 4

**Max:** 24

**Step:** 1

**Unit:** hours

#### Queue time

**Key:** queue

**Type:** number

**Default:** 1.5

**Min:** 0

**Step:** 0.5

**Unit:** days

#### Move and wait time

**Key:** move

**Type:** number

**Default:** 0.5

**Min:** 0

**Step:** 0.5

**Unit:** days

#### Safety lead time

**Key:** safety

**Type:** number

**Default:** 1

**Min:** 0

**Step:** 0.5

**Unit:** days

**Outputs:**

#### Total run hours

**Key:** run_total

**Expr:** qty * run

**Format:** decimal

#### Scheduled process hours

**Key:** proc_hours

**Expr:** (setup + run_total) / (eff / 100)

**Format:** decimal

**Description:** Setup plus run, divided by efficiency.

#### Process days

**Key:** proc_days

**Expr:** proc_hours / hours_day

**Format:** decimal

#### Total offset

**Key:** offset

**Expr:** queue + move + proc_days + safety

**Format:** decimal

**Description:** Days between order start and due date.

#### Offset rounded up (days)

**Key:** offset_ceil

**Expr:** ceil(offset)

**Format:** integer

**Primary:** true

**Description:** Use whole days when your ERP stores lead time that way.

#### Share of time spent processing

**Key:** touch_share

**Expr:** if(gt(offset, 0), proc_days / offset * 100, 0)

**Format:** percent

**Primary:** true

**Chart:**

#### Total offset vs order quantity

**Type:** line

**X:** qty

**From:** 10

**To:** 500

**Steps:** 25

**Series:**

- offset

**Disclaimer:** A simplified single operation model. Real routings sum several operations, overlap them, and use calendar rules. Validate against your ERP scheduling.

## Content

**Intro:** MRP back schedules a made-in-house order from the due date using a lead time offset. If that offset is too short orders start late; too long, you build early and hold stock. This calculator builds the number from its parts.

**Sections:**

#### How to use it

**Body:** Enter the order quantity, setup hours and run hours per unit from your routing. Set efficiency, the hours the work centre really runs per day, and the non-touch time: queue before the operation and move or wait time after it. Add any safety lead time you apply. The result is the offset in days and the share of that time spent actually working, which is often much smaller than people expect.

#### The formula

**Body:** Process hours equal setup plus quantity times run time, divided by efficiency. Process days are process hours divided by work hours per day. Total offset is queue plus move plus process days plus safety. The chart sweeps quantity so you can see how a larger lot raises run time while setup stays fixed. Queue and move typically dominate small orders, which is why shortening them often beats speeding up the machine.

**Bullets:**

- Process hours = (setup + qty x run) / efficiency
- Offset = queue + move + process days + safety
- Round up if your ERP stores whole days

#### Mistakes and ERP notes

**Body:** Do not double count: if your ERP routing already adds queue and move per operation, enter them once here. Do not use theoretical run times with no efficiency. For multi-operation routings, sum the operations or use the ERP's scheduling run; SAP computes lead time scheduling in routing and production order scheduling, and Epicor and SyteLine schedule from the job routing. Review fixed lead times on items that are made at different lot sizes.

**Cta:** Netray can compare the offsets in your ERP with actual job start and finish history, read-only.

**Faq:**

#### Is offset the same as lead time?

**Answer:** In practice yes for planning: it is the time between the start and the due date of an order. Some systems split it into in-house production time and processing time, so check your ERP's definition.

#### Why include efficiency?

**Answer:** Standard times assume ideal performance. If a cell typically delivers 85 percent of scheduled hours, dividing by that factor gives a more realistic duration.

#### Should I add safety lead time?

**Answer:** Only to cover real, measured variability. Hidden padding in every field adds up and inflates the lead time, which pushes MRP to release earlier and carry more work in process.

#### Does this replace finite scheduling?

**Answer:** No. It is an infinite capacity estimate. Use your scheduler for load aware dates.

## Search terms

manufacturing lead time calculator, planned order offset calculator, mrp backward scheduling calculator, queue move setup run time, in-house production time calculator, start date from due date manufacturing, routing lead time formula

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