Oracle EBS Item Lead Time Calculator (Fixed and Variable)
Oracle MRP offsets a planned order start date from the due date by the item's lead time, which is built from preprocessing, processing (fixed plus variable) and postprocessing days. This calculator shows the effect of each component and of order quantity on the total.
Your numbers
Time to prepare a PO or job before it starts (buy items usually).
Time that does not depend on order quantity (setup, queue).
Additional time per unit of order quantity.
Receiving, inspection and putaway after completion.
Your results
Approximation for planning discussions. Oracle schedules against the manufacturing calendar and the lead time source (item attributes or routing), so real dates will differ around weekends and holidays.
Total lead time vs order quantity
Sweeps Order quantity from 1 to 1000, holding your other inputs fixed.
Audit item lead times against reality
An optional review that compares master data lead times with receipt and completion history.
Optional. The tool and every export work without this. No spam.
How to use it
Take the values from the Lead Times region of the Item Attributes: Preprocessing, Processing, Postprocessing, Fixed and Variable lead time. Enter the order quantity you plan to use. The tool adds fixed time to variable time multiplied by quantity, then adds preprocessing and postprocessing. Switch the working days per week to see the calendar effect of a six day shop. Use the chart to find the quantity where lead time starts to climb enough that splitting the order into two jobs would help.
- Check the Make or Buy flag: buy items use preprocessing and postprocessing
- Compare the result to the supplier's quoted lead time
- Reflect the value in the Planning attributes before the next plan run
How Oracle uses lead time
For make items, MRP derives lead time from fixed and variable lead time and the order quantity, which makes lead time sensitive to lot size. For buy items, preprocessing and postprocessing cover internal handling before the order is placed and after it is received. Cumulative lead time, which adds up the longest path through the bill, is what customers actually wait for when material is not on the shelf. This tool covers a single level, so add your sub assembly paths when you quote a delivery date.
Worked example
With the defaults, processing is 3 plus 0.02 times 150, which is 6 days. Adding two days preprocessing and one day postprocessing gives 9 work days. On a five day week that is about 13 calendar days, close to two weeks. Increase the order quantity to 500 and processing becomes 13 days, total 16 work days, 23 calendar days. That is a useful conversation with sales when someone asks for a large lot with the same promise date.
Common mistakes
Lead time values copied from a legacy system are often wrong: too long, padded for old problems, or too short based on the best case. Padding on top of padding at each level of the bill inflates cumulative lead time and drives excess inventory. Measure actual lead times from receipt history and WIP completion dates, then update the item attributes. Also check that lead times are in days, not hours, and that variable lead time is per unit and not per batch.
Frequently Asked Questions
What is the difference between fixed and variable lead time?
Fixed lead time applies regardless of quantity, for example setup and queue. Variable lead time is the extra time per unit, so a bigger order takes longer. Processing lead time is the fixed part plus variable multiplied by the order quantity.
Does MRP use calendar days or work days?
MRP schedules against the manufacturing calendar, so lead times in the item attributes are treated as working days and skip non working days. This tool converts to approximate calendar days only to give you an easy comparison.
Where do I set preprocessing and postprocessing?
They are on the Item Attributes lead times region of the Master Item form in Oracle Inventory. Preprocessing and postprocessing mainly matter for buy items, and processing lead time for make items.
How do I find real lead times?
Compare PO approval or need by dates with actual receipt dates for buy items, and job release dates with completion dates for make items. Take a median across recent orders and update item attributes with that rather than a worst case.
Netray can compare the lead times on your EBS item master with actual receipt and completion history, and list the items where they disagree.
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