How do you calculate FAT workload hours?

Divide the number of FAT checkpoints by your completion throughput in checks per hour to get base test time, then multiply by one plus the retest/witness allowance. With 180 checks at 14 checks/hr and a 30% allowance, base time is 12.86 hr and required workload is 16.71 hr.

What is a good checks-per-hour throughput for a FAT?

It depends on protocol depth. Simple functional toggles run 20-40 checks/hr; instrumented performance points with data capture and witness signatures often drop to 8-15 checks/hr. The 14 checks/hr default reflects a mixed mechanical-and-controls protocol.

Why add a retest and witness allowance?

FATs rarely pass clean on the first pass, and customer witnesses slow the cadence with questions and re-demonstrations. The allowance (30% here) captures rework loops and the lost tempo, turning 12.86 base hours into 16.71 realistic hours.

FAT vs SAT workload, what is the difference?

FAT is run at your factory under controlled conditions; SAT (Site Acceptance Test) is run after installation at the customer's site, where utilities, integration, and travel delays inflate the allowance further. SAT allowances are typically higher than FAT allowances.

How do I shorten the FAT window?

Raise throughput by pre-running checks before the witness arrives, automating data capture, and clearing known failures during a dry-run FAT. Cutting the witnessed protocol to only the must-witness points and lowering the allowance both shrink the result.

Should I plan FAT as a single shift or multiple?

16.71 hr exceeds one shift, so plan a two-day witnessed FAT with an overnight buffer for failed-point rework. Trying to compress a 16+ hour protocol into one day almost guarantees a follow-up visit.

Industrial Equipment, Machinery & Capital Goods calculator

FAT Workload Calculator

Factory Acceptance Test (FAT) workload is the engineering and quality-team time needed to run every contractual checkpoint on a machine before it ships, including the inevitable retests and the slower pace when the customer is watching. Project managers and test engineers building capital-equipment delivery schedules use it to reserve bench time, book customer travel, and avoid the classic trap of promising a one-day FAT for a 180-point protocol. It matters because FAT sits on the critical path right before shipment: underestimate it and you delay the crane lift, the truck, and the customer's commissioning crew. This calculator converts a raw checkpoint count into realistic clock hours.

What this calculator does

Estimate factory acceptance test workload from FAT checkpoints, test throughput, and retest allowance.
Use it when planning test technicians, controls support, customer witness time, and documentation for FAT.
It computes the total clock hours to complete a FAT protocol, including a retest and customer-witness uplift on the base test time.

Formula used

Base FAT time = FAT checkpoints and test cases ÷ FAT completion throughput
Required FAT workload = base FAT time × retest and customer witness allowance multiplier

Inputs explained

FAT checkpoints and test cases:
FAT completion throughput:
Retest and customer witness allowance:

How to use the result

Use it when planning the FAT window for a built-to-order machine or skid, before you commit a date to the customer's witness team.
It assumes a steady checks-per-hour throughput; in reality the first few checks and any failed checks take far longer than the average, so treat the result as a planning midpoint, not a hard floor.

Current U.S. benchmarks

The U.S. prime lending rate is 6.75% (Federal Reserve via FRED, 2026-07-02). Payback and financing math should start from today's rate, not a remembered one.
Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).
The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate FAT workload hours? Divide the number of FAT checkpoints by your completion throughput in checks per hour to get base test time, then multiply by one plus the retest/witness allowance. With 180 checks at 14 checks/hr and a 30% allowance, base time is 12.86 hr and required workload is 16.71 hr.
What is a good checks-per-hour throughput for a FAT? It depends on protocol depth. Simple functional toggles run 20-40 checks/hr; instrumented performance points with data capture and witness signatures often drop to 8-15 checks/hr. The 14 checks/hr default reflects a mixed mechanical-and-controls protocol.
Why add a retest and witness allowance? FATs rarely pass clean on the first pass, and customer witnesses slow the cadence with questions and re-demonstrations. The allowance (30% here) captures rework loops and the lost tempo, turning 12.86 base hours into 16.71 realistic hours.
FAT vs SAT workload, what is the difference? FAT is run at your factory under controlled conditions; SAT (Site Acceptance Test) is run after installation at the customer's site, where utilities, integration, and travel delays inflate the allowance further. SAT allowances are typically higher than FAT allowances.
How do I shorten the FAT window? Raise throughput by pre-running checks before the witness arrives, automating data capture, and clearing known failures during a dry-run FAT. Cutting the witnessed protocol to only the must-witness points and lowering the allowance both shrink the result.

Last reviewed 2026-05-12.