Batch Reconciliation Explained: Where Manufacturers Actually Lose Material

Percentage yield is the final figure on a batch record, and it decides whether the batch is closed or investigated. By the time it is calculated, the batch has passed through four or more stages, each with its own loss mechanism. A single end-of-batch yield shows that material was lost but not where. Reconciling stage by stage shows where it went.

Watch: Granulation reconciliation

Granulation: the first checkpoint

Granulation is usually where a batch first commits to its final physical form, and it is also one of the more variable steps in solid dosage manufacturing. Losses here typically come from three places: fines carried out through the dust collection system, material adhering to mixer or granulator surfaces, and spillage during transfer to the dryer.

The reconciliation itself is simple. Compare the theoretical powder or granule weight from the batch formula with what you actually recover after drying:

% Loss = ((Theoretical weight − Actual weight) ÷ Theoretical weight) × 100

The reason this stage matters more than it might seem is compounding. A 3% loss at granulation is not only a 3% loss. It is a 3% shortfall that every later stage inherits and can only add to, never recover from. Catching an unusually large loss here, while the batch is still early, is far cheaper than discovering the same shortfall after tablets have already been compressed or coated.

A common mistake is recording the actual weight before drying is complete. The leftover moisture adds weight, so the loss looks smaller than it really is. Always reconcile on dried, in-spec material.

Compression: where losses become countable

Compression reconciliation compares the granules or powder fed to the tablet press with the tablets actually compressed. Instead of weight against weight, it is more useful to convert both sides into tablet counts, using the core tablet weight as the factor:

Theoretical tablets = (Granules/powder weight × 1,000,000) ÷ Core tablet weight
Actual tablets = (Compressed tablets weight × 1,000,000) ÷ Core tablet weight

This stage often reveals losses that granulation reconciliation alone would not catch: die-fill variation, tablets rejected during in-process weight checks, and material left behind in the feed frame or hopper at the end of a run. Reporting loss in both weight and tablet count is worth doing deliberately: weight loss is easier to compare across batches of different sizes, while tablet-count loss maps directly onto how many saleable units the batch actually produced, which is usually the number people actually care about when a batch record is being reviewed.

Coating: why weight alone is misleading

This is the stage where a simple reconciliation misleads. Coating adds weight to every tablet, so a coated batch always weighs more than the core batch it came from, even if some tablets were lost. A direct kilogram-to-kilogram comparison shows an apparent "gain" that hides the real tablet loss.

The fix is to reconcile on a tablet-count basis instead, deriving the expected coated batch weight from the theoretical tablet count and the actual average coated tablet weight:

Theoretical tablets (core) = (Core tablets weight × 1,000,000) ÷ Core tablet weight
Actual tablets (coated) = (Coated tablets weight × 1,000,000) ÷ Avg. coated tablet weight

Losses at this stage typically come from pan wall buildup, fines and chipped fragments carried out with the exhaust air, and tablets rejected during a post-coating appearance check. Because the numbers involved are less intuitive than a simple weight comparison, this is the stage where I most often see reconciliation done incorrectly in practice, usually by comparing core and coated weights directly and drawing the wrong conclusion from it.

Encapsulation: accounting for the shell

Encapsulation reconciliation has a similar wrinkle to coating, but from the opposite direction: a filled capsule's weight includes both the fill material and the empty shell, so comparing fill material weight directly against total filled capsule weight overstates the apparent loss unless the shell weight is accounted for separately.

The correct approach adds the shell weight to the target fill weight to get a theoretical filled capsule weight, then uses a separately measured actual average filled weight to convert the real output into a capsule count:

Theoretical filled capsule weight = Target fill weight + Shell weight
Actual capsules = (Total filled capsules weight × 1,000,000) ÷ Avg. filled capsule weight (actual)

Losses here concentrate around capsules rejected for being under- or overweight during in-process checks, and fill material lost to dust collection or machine surfaces during the run.

Stage-wise versus end-of-batch reconciliation

Stage-wise records also build a track record: if compression consistently shows a higher loss than granulation and coating, the cause may lie in press settings, tooling wear or the formulation itself.

Calculators are available for each stage: granulation, compression, coating, encapsulation, blister packing and final packing.