MRP Planned Order Release Date Calculator
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.
Your numbers
Calendar days from today to the date the net requirement is due.
Planned manufacturing or purchase lead time from the item master.
Extra buffer added by the planning parameters.
Dock to stock time, including incoming inspection.
Supplier ship time or inter-plant move time.
Your results
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.
Release date from today vs item lead time
Sweeps Item lead time from 1 to 60, holding your other inputs fixed.
Check release dates against your ERP data
Optional: we can review a sample of your planned orders and show where offsets are missing or double counted.
Optional. The tool and every export work without this. No spam.
How to use it
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.
- 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
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
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
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.
- 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.
Frequently Asked Questions
Why does my ERP show a different release date?
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?
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?
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?
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.
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.
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