How do you calculate component attrition rate?

Divide attrited or lost components by total components issued. With 640 components lost out of 185,000 issued, attrition is 0.346% — well under a 0.4% target, leaving a 0.054-point cushion.

What is a good component attrition rate for SMT?

For standard chip components, 0.2-0.5% is typical; fine-pitch, micro-passives (0201/01005), and complex feeders run higher. A blended rate at or below your kitting overage assumption, like the 0.346% here against a 0.4% target, indicates healthy material control.

How is attrition different from scrap?

Scrap is components or assemblies condemned after use or inspection; attrition is parts consumed by the process that never reach a board — pickup losses, splice waste, and handling loss. Attrition drives kitting overage; scrap drives yield cost.

How much overage should I add to a kit?

Set overage to at least your demonstrated attrition rate plus a small safety margin. If attrition runs 0.346%, kitting at 0.5% overage covers normal loss with buffer; kitting at exactly 0.346% risks a shortage on any bad day.

Why is my attrition rate suddenly climbing?

Common causes are worn nozzles, mis-set feeder pitch, marginal tape splices, vibration knocking parts off, or an ESD/handling issue. A rising blended rate justifies pulling per-feeder attrition data to isolate the offending position.

What does the gap to target mean?

It is target minus actual. A positive 0.054-point gap means you are beating target and have headroom; a negative gap means attrition exceeds plan and your kits will run short unless overage is raised.

Electronics Manufacturing calculator

Component Attrition Calculator

Component attrition is the share of electronic components issued to the line that never make it onto a good board — lost to placement-machine pickups, reel splicing, ESD damage, tombstones swept off, or simply dropped. SMT material planners and buyers use the attrition rate to set kitting overage, size buffer stock, and reconcile inventory against BOM consumption. It matters because under-estimating attrition starves the line mid-shift, while over-estimating it ties up cash in excess tiny passives. On a high-mix line running millions of 0402s, even a few tenths of a percent is real money and real line stoppages.

What this calculator does

Measure component attrition percentage from lost, scrapped, or consumed extra parts versus total issued parts.
a materials planner is checking whether component attrition is eroding kit accuracy or quote margin
It computes the percentage of issued components lost to attrition and the gap between that rate and your planning target.

Formula used

Component attrition rate = attrited or lost components ÷ total components issued
Attrition gap to target = target component attrition - component attrition rate

Inputs explained

Attrited or lost components:
Total components issued:
Target component attrition:

How to use the result

Use it when setting kitting overage factors, reconciling line returns against issued quantity, or auditing a feeder or machine that seems to chew through parts.
It is a blended rate; a single low number can hide one machine or one part number with a severe pickup problem, so pair it with per-component or per-feeder tracking.

Current U.S. benchmarks

The producer price index for copper and brass mill shapes stands at 559.593 (BLS, May 2026), up 76.8% from a year earlier. Quotes priced off last quarter's material cost miss this move. Global copper trades at $13,484 per tonne (IMF via FRED, May 2026).
The U.S. has 11,261 computer and electronic products establishments employing about 815,443 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate component attrition rate? Divide attrited or lost components by total components issued. With 640 components lost out of 185,000 issued, attrition is 0.346% — well under a 0.4% target, leaving a 0.054-point cushion.
What is a good component attrition rate for SMT? For standard chip components, 0.2-0.5% is typical; fine-pitch, micro-passives (0201/01005), and complex feeders run higher. A blended rate at or below your kitting overage assumption, like the 0.346% here against a 0.4% target, indicates healthy material control.
How is attrition different from scrap? Scrap is components or assemblies condemned after use or inspection; attrition is parts consumed by the process that never reach a board — pickup losses, splice waste, and handling loss. Attrition drives kitting overage; scrap drives yield cost.
How much overage should I add to a kit? Set overage to at least your demonstrated attrition rate plus a small safety margin. If attrition runs 0.346%, kitting at 0.5% overage covers normal loss with buffer; kitting at exactly 0.346% risks a shortage on any bad day.
Why is my attrition rate suddenly climbing? Common causes are worn nozzles, mis-set feeder pitch, marginal tape splices, vibration knocking parts off, or an ESD/handling issue. A rising blended rate justifies pulling per-feeder attrition data to isolate the offending position.

Last reviewed 2026-05-12.