Order fill rate calculator.

Worked example

Customers ordered 5,000 units and you filled 4,750: 4,750 / 5,000 x 100 = 95.0% unit fill rate. If 352 of 400 orders shipped complete, the order fill rate is 352 / 400 x 100 = 88.0%. The order rate is lower because one missing unit makes the whole order incomplete.

How it works

Fill rate measures the number of units filled as a percentage of the total ordered (Wikipedia, Service level). That is the unit fill rate used here. The order fill rate applies the same idea to whole orders and is stricter.

Decide which orders count as filled: from stock on hand, on time, or eventually. This page leaves that rule to you; enter the figures that follow your own rule and keep it consistent.

Fill rate is not the same as cycle service level. Cycle service level is the probability of no stockout during a replenishment cycle; fill rate is the share of demand actually met. A 95% cycle service level therefore does not tell you the fill rate.

Sources (opened 2026-10-18): Service level - Wikipedia. The formula wording above follows these pages; the example figures and all arithmetic are ours.

Inputs are user-entered figures. Results are planning estimates, not financial advice or a forecast. Everything runs in your browser. Nothing you type is sent or stored.

FAQ

How do you calculate fill rate?

Divide units shipped by units ordered and multiply by 100. 4,750 of 5,000 is 95%.

What is the difference between unit and order fill rate?

Unit fill rate counts every unit. Order fill rate counts an order only if all of it shipped, so it is usually lower.

Is fill rate the same as service level?

Not exactly. Fill rate is the share of demand met. Cycle service level is the probability of no stockout in a cycle.

Does this include backorders filled later?

Only if you count them as filled. Enter the figures that match your own definition.