Fill Rate Calculator

Free fill rate calculator. Enter units or orders demanded and units or orders shipped complete to find your fill rate percentage.

Fill Rate Calculator

See what share of demand you can fill immediately from stock on hand. No signup required.

By Tibeau De Grauwe, FounderUpdated September 2026

  • 25 products free
  • No credit card
  • 10-min setup

Fill rate measures how much of demand you could ship right away from stock you already had, without a backorder, substitution, or stockout.

Fill Rate Calculator

Fill rate

96.0%

480 of 500 filled immediately from stock

The fill rate formula

Fill rate = (units or orders shipped complete ÷ units or orders demanded) × 100, over a chosen period. Use the same unit consistently: unit fill rate treats every unit the same, order fill rate only counts an order as filled if every line shipped in full, so pick one measure and stick with it for comparisons to mean anything.

A persistently low fill rate on a specific SKU is almost always a reorder point or safety stock issue worth recalculating against recent demand and lead-time data, rather than a one-off.

See also: the fill rate glossary entry, the reorder point calculator, the safety stock calculator.

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What our customers say

Super Kind! Quick replies from their support and very easy fixes, changed the dashboard a bit and customized it. Also gave me 450 items extra on the free plan just for me. Highly recommend and again great service!

Erasable Trading AU

Best customer service! Stockflow's customer support is fast and extremely helpful. They assisted me with customization of the software to improve my experience as a user.

Justin M.

Co-Owner, Consumer Goods

Frequently asked questions

What is a good fill rate?
Many operations target 95-98% for unit fill rate, and treat order fill rate — the strictest measure, where a single short line fails the whole order — as the number that best reflects the actual customer experience.
What is the difference between unit fill rate and order fill rate?
Unit fill rate treats every unit the same regardless of order. Order fill rate only counts an order as filled if every line on it shipped complete — a single out-of-stock item drops the whole order to a miss.