Free tool
Par level calculator
Enter daily usage and your delivery schedule to get the par level for each item and how much to order to get back to it.
Your delivery cycle
Days and buffer apply to every item below.
| Item | Daily usage | On hand | Par | Order | Remove |
|---|---|---|---|---|---|
| 101 | 63 |
Par level
101 units
- Days of cover
- 7
- Order now
- 63 units
Par is rounded up to a whole unit. Order is par minus what is on hand, never below zero.
The formula
Par level = daily usage × (days between deliveries + lead time) × (1 + buffer %)
Order quantity = par level − on hand (never below zero)
- Daily usage
- Units used or sold on a typical day.
- Days between deliveries
- How often the item is delivered: 7 for a weekly delivery.
- Lead time
- Days between placing the order and the stock arriving. Zero when you order at delivery for the next one.
- Buffer
- A cushion for a busier than usual cycle, as a percentage of cycle usage or as a fixed number of units.
- On hand
- Units on the shelf when you place the order.
Worked example
- A coffee shop uses 12 units a day and takes a delivery every 7 days, ordering the day the truck comes, so lead time adds 0 days and cover is 7 days.
- Usage over the cycle is 12 × 7 = 84 units.
- A 20% safety buffer gives 84 × 1.2 = 100.8 units, rounded up to a par level of 101.
- With 38 on the shelf, the order is 101 − 38 = 63 units.
When it applies
- Items delivered on a fixed schedule, such as a weekly supplier drop.
- Steady usage that looks about the same from one cycle to the next.
- Short, reliable lead times where a flat cushion is enough.
When it breaks down
- Usage that spikes with promotions, weather or seasons: a par set on an average cycle runs out on a busy one.
- Long or unreliable lead times. The buffer is a flat percentage, not a measure of how much demand and delivery vary; that is what safety stock models.
- Items ordered whenever they run low rather than on a schedule, where a reorder point fits better.
Common mistakes
Setting par once and never revisiting it
Usage drifts as menus, ranges and seasons change. A par that was right in spring is short or bloated by autumn.
Forgetting lead time
If the order takes two days to arrive, stock has to cover the cycle and those two days. Leaving lead time out sets par too low.
One flat buffer for every item
A steady staple and a volatile item need different cushions. The same percentage over-stocks one and under-protects the other.
Questions
What is par level in inventory?
Par level is the amount of an item you want on hand after each delivery: enough to cover usage until the next delivery arrives, plus a buffer. Each time you order, you order the difference between par and what is on the shelf.
What do par levels determine?
They determine how much to order. Ordering par minus on hand brings each item back to the same level every cycle, so the order quantity changes with what was used rather than being a fixed amount.
What is the difference between par level and reorder point?
Par level is a target stock level you top up to on a schedule. A reorder point is a trigger: when stock falls to it, you place an order. Par suits fixed delivery days; a reorder point suits items you can order any day.
What is the difference between par level and safety stock?
Safety stock is the extra stock held against variation in demand and lead time, sized from how much they vary and the service level you want. The buffer in a par level is a simpler, flat cushion. Par includes the cycle's expected usage; safety stock is only the cushion.
Is par level the same as par stock?
Yes. Par stock and par level are used interchangeably for the target quantity of an item to hold after each delivery.
Related
Published by Skuvelo. Results are estimates computed from the figures you enter, not a reading of your own sales or stock.
A calculator answers once. Skuvelo keeps answering.
This tool computes one number from what you type. Skuvelo computes it continuously, for every SKU, from your own sales and stock.