# MRP Planned Order Release Date Calculator

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

## Short answer

Back-schedule a planned order from its need date using lead time, safety lead time, receiving and transit, and see whether the release date is already past.

## Category

supply-chain

## Audience

- Material planner
- Production planner
- Buyer

## Tool

**Kind:** calculator

**Inputs:**

#### Days until need date

**Key:** need_in

**Type:** number

**Default:** 45

**Min:** 0

**Step:** 1

**Unit:** calendar days

**Help:** Calendar days from today to the date the net requirement is due.

#### Item lead time

**Key:** lead_time

**Type:** number

**Default:** 20

**Min:** 0

**Step:** 1

**Unit:** workdays

**Help:** Planned manufacturing or purchase lead time from the item master.

#### Safety lead time

**Key:** safety_lt

**Type:** number

**Default:** 3

**Min:** 0

**Step:** 1

**Unit:** workdays

**Help:** Extra buffer added by the planning parameters.

#### Receiving and inspection

**Key:** receiving

**Type:** number

**Default:** 2

**Min:** 0

**Step:** 1

**Unit:** workdays

**Help:** Dock to stock time, including incoming inspection.

#### Transit time

**Key:** transit

**Type:** number

**Default:** 5

**Min:** 0

**Step:** 1

**Unit:** workdays

**Help:** Supplier ship time or inter-plant move time.

#### Workdays per week

**Key:** workdays

**Type:** select

**Default:** 5

**Options:**

##### 5 days

**Value:** 5

##### 6 days

**Value:** 6

##### 7 days

**Value:** 7

**Outputs:**

#### Total offset

**Key:** total_wd

**Expr:** lead_time + safety_lt + receiving + transit

**Format:** number

**Description:** Sum of all offsets in workdays.

#### Offset in calendar days

**Key:** cal_days

**Expr:** ceil(total_wd * 7 / workdays)

**Format:** days

**Description:** Workdays converted to calendar days using the weekly pattern.

#### Release date from today

**Key:** release_in

**Expr:** need_in - cal_days

**Format:** days

**Primary:** true

**Description:** Negative means the release date has already passed.

#### Days past due at release

**Key:** late_days

**Expr:** max(0, 0 - release_in)

**Format:** days

**Description:** How many calendar days the order is already late.

#### Lead time compression needed

**Key:** compress

**Expr:** if(gt(late_days,0), ceil(late_days * workdays / 7), 0)

**Format:** number

**Primary:** true

**Description:** Approximate workdays that must be removed from the offset to be on time.

**Chart:**

#### Release date from today vs item lead time

**Type:** line

**X:** lead_time

**From:** 1

**To:** 60

**Steps:** 30

**Series:**

- release_in

**Disclaimer:** Uses a simple workday to calendar conversion with no holiday calendar. Your ERP uses its own plant calendar, so treat this as a sanity check.

## Content

**Intro:** MRP schedules backward: it starts at the date a net requirement is needed and subtracts lead times to find when the planned order must be released. This calculator shows that arithmetic so you can explain or challenge a date your ERP produced.

**Sections:**

#### How to use it

**Body:** Enter the number of calendar days to the need date, then the offsets that apply to the item: lead time, safety lead time, receiving and transit. The calculator adds them in workdays, converts to calendar days using your weekly pattern, and subtracts from the need date. A negative release date means the planned order should already have been released, which is why MRP shows a reschedule-in or release-now exception.

**Bullets:**

- Use workdays for lead times that your ERP stores in workdays.
- Set the weekly pattern to match the plant calendar.
- Check the compression figure to see how much time must be removed.

#### The method behind it

**Body:** Backward scheduling subtracts every offset from the due date: release date equals need date minus lead time, safety lead time, receiving time and transit time. Most systems apply these offsets against a working calendar, skipping weekends and shutdown days. Safety lead time moves the receipt date earlier than the need date, so the order is planned to arrive before it is required, at the cost of extra inventory days. Receiving and transit are often forgotten in the item master, which is a common reason dates look correct but parts arrive late.

#### Reading the result

**Body:** With 45 days to the need date and a total offset of 30 workdays on a five day week, the offset is 42 calendar days, so the order releases in 3 days. Raise the lead time to 30 workdays and the release date goes negative. The chart sweeps lead time so you can see exactly where a supplier lead time change turns a comfortable plan into an expedite. Use it when negotiating lead time commitments or deciding whether to buy from a faster source.

#### Common mistakes

**Body:** Planners often double count safety lead time because the supplier quote already includes a buffer. Others mix calendar and workday lead times, which understates the offset by about 40 percent on a five day week. Also check whether your ERP applies lead time to the order or to a routing, because routing based scheduling can produce different dates than a fixed item lead time.

**Bullets:**

- Do not add transit twice when the lead time is door to door.
- Confirm whether the plant calendar includes holidays.
- Review items where the release date is regularly in the past.

**Cta:** If planners spend time reconciling release dates against supplier promises, Netray can build a read-only view over your ERP data that flags orders whose offsets do not add up.

**Faq:**

#### Why does my ERP show a different release date?

**Answer:** ERPs use plant calendars with holidays and shutdown days, and some apply routing lead times instead of the item master lead time. This calculator uses a plain workday ratio, so expect differences of a few days.

#### What is safety lead time?

**Answer:** It is a buffer in time added to the lead time so that supply arrives before it is needed. It protects against late delivery without carrying safety stock, but it still increases average inventory because material arrives early.

#### Should receiving time be included?

**Answer:** Yes, when material is not available to production until inspection and put-away finish. If your ERP does not model it, add it to the lead time or planning parameter so planned receipts reflect real availability.

#### What does a negative release date mean?

**Answer:** The order should have been released already. MRP typically raises a release now or reschedule exception, and the planner must either compress lead time, expedite the supplier, or move the customer date.

## Search terms

mrp planned order release date, lead time offsetting calculator, mrp backward scheduling, safety lead time calculator, planned order start date calculation, mrp lead time offset, order release date calculator, workday lead time to calendar days

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