First Time Through (FTT) measures the percentage of units or transactions that pass through a process correctly the first time without scrap, rework, repair, retest, or correction.
Definition
First Time Through (FTT) is a quality-yield metric showing the percentage of units, transactions, or cases that complete a process correctly the first time without rework, repair, retest, sorting, or correction. It focuses attention on whether the process is producing acceptable output without hidden factory effort.
FTT is often calculated as good first-time units divided by total units processed, multiplied by 100 percent. The exact definition must be clear because organizations may treat rework, repair, scrap, retest, or minor correction differently.
History
First-time quality measures grew from manufacturing yield, quality cost, and Lean waste-reduction practice. Teams needed a metric that showed how much of the process output was right without relying on downstream correction.
Six Sigma and Lean teams use FTT alongside first pass yield, rolled throughput yield, DPMO, COPQ, and process capability to understand quality loss and prioritize root cause work.
When to Use
Use FTT when measuring process quality, hidden rework, launch performance, customer-impact risk, or improvement results. It is useful for production lines, inspection processes, order entry, claims, billing, software testing, maintenance work orders, and healthcare processes.
FTT is especially helpful when final shipped quality looks acceptable because defects are being caught and corrected internally. A high final acceptance rate can still hide poor first-time performance.
Step-by-Step
- Define the unit. Clarify what counts as one part, order, case, transaction, request, or service instance.
- Define first-time good. State exactly what qualifies as correct without correction.
- Define exclusions carefully. Decide how to treat scrap, rework, retest, missing information, customer changes, and planned inspections.
- Collect process counts. Track total units entering the process and units that pass first time.
- Calculate FTT. Divide first-time-good units by total units and multiply by 100 percent.
- Stratify results. Review by product, shift, machine, supplier, customer, defect type, operator, work type, or time period.
- Link to losses. Translate poor FTT into rework hours, scrap, delay, capacity loss, COPQ, and customer risk.
- Improve root causes. Use Pareto, RCA, FMEA, standard work, mistake proofing, and control plans.
- Monitor sustainment. Track FTT over time with clear ownership and reaction rules.
Examples
- Assembly line: 950 of 1,000 units pass final station without rework, giving 95 percent FTT.
- Billing process: Invoices that need correction before release are counted as not first-time-through.
- Maintenance work: Work orders closed without return visits or repeat failure count as first-time good.
- Software testing: User stories that pass acceptance testing without defect rework improve FTT.
- Healthcare documentation: Patient records completed without missing fields or coding correction count as first-time through.
Common Pitfalls
- Counting corrected units as good. FTT should reveal hidden rework, not hide it.
- Unclear definitions. Teams must agree what rework, retest, repair, and correction mean.
- Focusing only on final yield. Final yield can look good while internal effort is high.
- No defect categorization. FTT tells how much is right first time; Pareto categories explain why not.
- Ignoring process mix. Complex products or transactions may need stratified comparison.
- Using FTT punitively. The metric should drive process improvement, not fear-based reporting.