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Order Fill Rate Calculator

Measure the share of demand you actually served — by unit and by order line.

Fill rate is the scoreboard your safety stock is playing for. Every buffer decision, every service-level assumption, every expedite eventually shows up here as a percentage. It is also the metric most often quoted in a way that hides bad news — which is why it is worth calculating two ways.

Unit fill rate

Line fill rate
Units short

Share of requested units you shipped complete and on time.

Your numbers

units
units
lines
lines

The formula

Unit fill rate = Units shipped ÷ Units ordered · Line fill rate = Lines filled complete ÷ Lines ordered

Unit fill rate flatters you; line fill rate is what the customer experiences.

What it means

Stockout — full definition

Read in the glossary

How to use it

  1. 1

    Count what was requested, not what you accepted. Demand you refused to take is still demand you failed to serve.

  2. 2

    Count shipments as on time against the date the customer asked for, not the date you promised after the fact.

  3. 3

    Calculate line fill alongside unit fill — a large order shipped 95% complete still arrives as an incomplete order.

Where it goes wrong

  • Unit fill rate is systematically kinder than line fill rate, because a handful of big lines shipped in full can carry many small ones that shipped short. Report both or you will not see the problem.

  • Fill rate measured only on orders you accepted is a vanity metric. Lost quotes and refused orders belong in the denominator.

Worked example

The gap between two true numbers

4,750 of 5,000 units shipped is a 95.0% unit fill rate — respectable. But if 28 of 420 order lines went out incomplete, line fill is 93.3%, and 28 customers had a conversation about it. Both figures are accurate; only one predicts the complaints.

Common questions

Is fill rate the same as service level?

No. Service level in the safety-stock formula is the probability of not stocking out during a replenishment cycle. Fill rate measures the share of demand actually served. The first is an input to planning; the second is the outcome.

Should backorders shipped later count as filled?

Not in on-time fill rate. Track them as a separate recovery metric, otherwise a chronically late operation can report near-perfect fill.

What fill rate should we target?

Set it by item class and customer contract, not globally. Chasing 99% across a long C-class tail costs far more in inventory than the service is worth.

Let AWRA do this on your live data

This calculator works on one set of numbers. AWRA OpsHub keeps order fill rate calculator results current across every item, supplier and location — automatically.