Kit Calculations

How to Calculate Fill Yield, Assembly Labor, and Lot Release for Diagnostic Kits

The core diagnostics manufacturing formulas run end to end with real units, from a 50 liter fill yield down to AQL sample load per lot.

Four numbers decide whether a diagnostics line makes money: reagent fill yield, assembly labor per kit, sterile pouch throughput, and lot release sample load. Each has a clean formula, and each input traces back to a document you already own, the batch record, the routing, or the sampling plan. This guide runs the arithmetic end to end with real units. Start with fill yield, because a 2 percent swing on a 50 liter bulk batch of immunoassay conjugate can cost thousands of vials. The Reagent Fill Yield calculator handles the bookkeeping, but you should know what sits underneath the output before you trust it on a quote.

Fill yield is usable volume divided by bulk volume prepared, then converted to vials. Take a 50.0 liter bulk lot, a 1.00 mL target fill, and a validated 3 percent overfill, so each vial actually draws 1.03 mL. Subtract line dead volume, roughly 1.2 liters trapped in tubing, pumps, and the final flush. Usable volume is 48.8 liters, or 48,800 mL. Divide by 1.03 mL to get 47,378 vials. Against a theoretical 50,000 vials at exactly 1.00 mL, fill yield is 94.8 percent. The overfill and the dead volume together explain the entire 5.2 percent loss, and both are levers you control.

Assembly labor per kit is the sum of standard times across every station divided by line efficiency. Suppose a respiratory panel kit has 12 components across 6 stations, with station standard times of 40, 55, 38, 50, 42, and 35 seconds. The bottleneck is 55 seconds, so line takt is 55 seconds and hourly output is 3,600 divided by 55, or 65 kits per hour. Total hands on labor is 260 seconds per kit, which across 6 operators means 4.33 minutes of paid labor per kit. Feed those station times into the Test Kit Assembly Labor calculator to expose the bottleneck station and rebalance the line.

Sterile pouch throughput starts from sealer cycle time and derates for real uptime. A rotary bar sealer running a 4.0 second cycle has a theoretical rate of 3,600 divided by 4.0, or 900 pouches per hour. Apply an OEE of 0.75, covering film changeovers, seal integrity checks, and micro stops, and effective output falls to 675 pouches per hour. Over a 7.5 hour productive shift that is 5,062 pouches. If assembly upstream runs 65 kits per hour on one line, a single sealer covers roughly 10 lines. The Sterile Pouch Throughput calculator lets you match sealer count to assembly demand instead of guessing.

Lot release sample load comes from your AQL sampling plan, not a guess. Under ANSI ASQ Z1.4, a lot of 10,000 kits at general inspection level II maps to code letter L and a sample size of 200. At an AQL of 1.0, you accept on 5 defects and reject on 6. If each sampled kit needs 3 QC checks at 4 minutes each, that is 200 times 12 minutes, or 2,400 minutes, which is 40.0 QC labor hours per lot. Double the lot to 20,000 and the code shifts to M, sample size 315, so load scales sublinearly. The Lot Release Sample Load calculator maps lot size straight to hours.

Shelf life inventory buffer answers how much finished stock you can safely hold before expiry destroys value. Buffer days equal remaining shelf life minus the sum of distribution transit, customer minimum acceptance dating, and your own release cycle. A reagent kit with 18 months total shelf life, 21 days release testing, 14 days transit, and a customer requirement of 12 months remaining on receipt leaves 540 minus 365 minus 35, or 140 sellable days of buffer. At a demand of 800 kits per week, the ceiling is 16,000 kits before you risk write offs. The Shelf-Life Inventory Buffer calculator flags where dating collapses that window.

Two supporting calculations tie the batch together. Batch Genealogy Workload estimates review time for the device history record, roughly component count times lots per component times 6 to 10 minutes of reconciliation, so a 12 component kit drawing 2 lots each runs 24 line items and 2.4 to 4.0 hours of record review. Kit Component Shortage Risk converts on hand quantity and lead time variance into a stockout probability. Run fill yield, assembly labor, pouch throughput, and sample load in that order, and every downstream schedule and cost number inherits inputs you have already verified against the batch record rather than reworking them later.

Published 2026-07-02.