# SAP Safety Stock and Reorder Point Calculator

> Source: https://netray.co/tools/sap-pp-safety-stock-reorder-point-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Work out a statistically sound safety stock and reorder point for the MRP 1 view of the material master, and see how lead time moves them.

## Category

sap

## Erp

SAP S/4HANA

## Audience

- SAP PP consultant
- MRP controller
- Production planner

## Tool

**Kind:** calculator

**Inputs:**

#### Average daily demand

**Key:** daily_demand

**Type:** number

**Default:** 120

**Min:** 0

**Step:** 5

**Unit:** units/day

**Help:** Mean consumption per working day, for example from MC.9 or the consumption values in MM03.

#### Standard deviation of daily demand

**Key:** demand_sd

**Type:** number

**Default:** 35

**Min:** 0

**Step:** 1

**Unit:** units/day

**Help:** Spread of daily demand around the mean. Use weekly data divided down if daily history is thin.

#### Replenishment lead time

**Key:** lead_time

**Type:** number

**Default:** 14

**Min:** 1

**Step:** 1

**Unit:** days

**Help:** Planned delivery time plus goods receipt processing time for externally procured parts, or in-house production time for made parts.

#### Standard deviation of lead time

**Key:** lead_sd

**Type:** number

**Default:** 3

**Min:** 0

**Step:** 0.5

**Unit:** days

**Help:** How much actual lead time varies from the master data value.

#### Target cycle service level

**Key:** service

**Type:** select

**Default:** 0.95

**Options:**

##### 90%

**Value:** 0.9

##### 95%

**Value:** 0.95

##### 97.5%

**Value:** 0.975

##### 99%

**Value:** 0.99

##### 99.5%

**Value:** 0.995

**Outputs:**

#### Z score

**Key:** z

**Expr:** normsinv(service)

**Format:** decimal

**Description:** Standard normal quantile for the chosen service level.

#### Demand over lead time

**Key:** lt_demand

**Expr:** daily_demand * lead_time

**Format:** integer

**Description:** Expected consumption while waiting for replenishment.

#### Combined variability over lead time

**Key:** sigma_lt

**Expr:** sqrt(lead_time * pow(demand_sd, 2) + pow(daily_demand, 2) * pow(lead_sd, 2))

**Format:** decimal

**Description:** Square root of the sum of demand variance and lead time variance effects.

#### Safety stock (MARC-EISBE)

**Key:** ss

**Expr:** ceil(z * sigma_lt)

**Format:** integer

**Primary:** true

**Description:** Value to maintain as safety stock in the MRP 2 view.

#### Reorder point (MARC-MINBE)

**Key:** rop

**Expr:** ceil(lt_demand + ss)

**Format:** integer

**Primary:** true

**Description:** Reorder point for MRP type VM. Stock plus receipts at or below this triggers a requisition.

#### Safety stock in days of demand

**Key:** ss_days

**Expr:** if(gt(daily_demand, 0), ss / daily_demand, 0)

**Format:** decimal

**Description:** Handy sanity check against SAP range of coverage settings.

**Chart:**

#### Safety stock and reorder point vs lead time

**Type:** line

**X:** lead_time

**From:** 1

**To:** 60

**Steps:** 30

**Series:**

- ss
- rop

**Disclaimer:** Assumes roughly normal demand and independent demand and lead time variability. For lumpy or intermittent demand, validate with simulation or history before loading into the material master.

## Content

**Intro:** Safety stock in SAP is a single number in the material master, but the right number depends on how demand and lead time both vary. This calculator uses the standard combined variability formula and gives you the safety stock and reorder point ready to key into the MRP views.

**Sections:**

#### How to use this calculator

**Body:** Enter average and standard deviation of daily demand, the replenishment lead time and its variability, and pick a cycle service level. The result shows safety stock and a reorder point. For externally procured parts, lead time is the planned delivery time plus goods receipt processing time. For in-house parts, use in-house production time or the scheduled lead time from the routing.

**Bullets:**

- Pull demand history from MC.9 or the consumption view in MM03 and compute the standard deviation in Excel.
- Pull actual lead times from purchase order history in ME2M or ME80FN, comparing delivery dates with order dates.
- Start at 95% and raise service level only for critical or long lead parts.

#### The formula behind the result

**Body:** Safety stock equals Z times the square root of (lead time times demand variance plus mean demand squared times lead time variance). Z comes from the normal distribution for the chosen service level. The reorder point equals mean demand during lead time plus safety stock. This is the classic combined formula used in inventory textbooks and is what most planners mean by statistical safety stock.

**Bullets:**

- If lead time never varies, the second term drops out and the formula reduces to Z times demand sigma times root lead time.
- If demand is constant, only lead time variability drives safety stock.

#### Where the numbers go in SAP

**Body:** Safety stock is maintained in the MRP 2 view (field Safety Stock, MARC-EISBE). The reorder point is in the MRP 1 view (field Reorder Point, MARC-MINBE) and is only used by reorder point planning, MRP type VM and VB. MRP types PD use safety stock as a stock buffer against forecast or requirement error but ignore the reorder point. Dynamic safety stock can also be driven by the range of coverage profile, which is a different method that scales buffer with future requirements.

#### Common mistakes

**Body:** Planners often set safety stock once and never revisit it. Others add safety time and safety stock together, buffering the same uncertainty twice. A third mistake is using the lead time from master data when real lead times are longer, which understates the reorder point.

**Bullets:**

- Review safety stock after any change in supplier, lot size or planned delivery time.
- Use safety time for timing risk and safety stock for quantity risk, not both for the same risk.
- Check that the unit of measure of the demand data matches the base unit of measure.

**Cta:** Netray can read consumption and lead time history directly from your SAP system and propose safety stock and reorder point values by material, for planner approval before anything is changed.

**Faq:**

#### Which SAP field holds safety stock?

**Answer:** Safety stock is in the MRP 2 view of the material master, field Safety Stock (MARC-EISBE). The reorder point sits in the MRP 1 view (MARC-MINBE) and applies only to reorder point planning procedures such as MRP type VM.

#### What service level should I choose?

**Answer:** Ninety five percent is a common starting point for regular A and B parts. Raise it for parts that stop a line, and lower it for cheap parts that are easy to expedite. Each step up costs disproportionately more stock.

#### Can SAP calculate safety stock automatically?

**Answer:** SAP can compute dynamic safety stock through a range of coverage profile, and S/4HANA also offers MRP Live based planning with safety stock settings. Statistical service level methods usually need a calculation outside the material master, like this one.

#### Does safety stock in SAP count as available stock?

**Answer:** MRP treats safety stock as stock that should not be consumed to cover normal requirements. If stock falls into the safety stock, MRP issues an exception message to rebuild it.

## Search terms

sap safety stock calculation, sap reorder point calculator, safety stock formula sap, sap eisbe safety stock, sap minbe reorder point, mrp safety stock calculator, sap mrp type vm reorder point, safety stock service level calculator

---
Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json