Pharmaceutical Analysis

Percentage Recovery Calculator

How much of the starting material you got back after an extraction, purification, assay or analytical procedure.

Experiment

Sample / procedure name (optional)

Printed on the lab result card.

Amounts

Mass with mass, volume with volume. % and IU compare only with themselves.

Initial amount

Amount before the procedure.

Amount recovered

Amount found after the procedure.

Try a worked example

Laboratory calculation card

Enter the initial amount and the amount recovered.

% Recovery = (Amount recovered / Initial amount) × 100

Amount = Concentration × Volume

% Loss = 100 − % Recovery

Both amounts must be in the same unit before dividing. Masses are converted through grams and volumes through millilitres, so 850 mg recovered from 1 g is 0.85 g / 1 g × 100 = 85%. In concentration mode, a mass-per-volume concentration is converted to mg/mL and a molar one to mmol/mL; multiplying by the volume in mL then gives each amount in mg or mmol.

Worked example: recovery after a liquid–liquid extraction

Illustrative values. A student shakes 50 mL of an aqueous drug solution (250 µg/mL) with an organic solvent, evaporates the organic layer and redissolves the residue in 25 mL of solvent. The redissolved extract assays at 0.462 mg/mL. How much of the drug was recovered? Enter it in Concentration × volume mode.

Initial concentration (C₁): 250 µg/mL
Initial volume (V₁): 50 mL
Recovered concentration (C₂): 0.462 mg/mL
Final volume (V₂): 25 mL

Put both concentrations in the same unit
C₁ = 250 µg/mL × 0.001 = 0.25 mg/mL (C₂ is already in mg/mL)
Initial amount = C₁ × V₁
0.25 mg/mL × 50 mL = 12.5 mg
Amount recovered = C₂ × V₂
0.462 mg/mL × 25 mL = 11.55 mg
% Recovery = (recovered / initial) × 100
(11.55 mg / 12.5 mg) × 100 = 0.924 × 100 = 92.40 %
% Loss = 100 − % recovery
100 − 92.40 = 7.60 %

% Recovery = 92.40 % (7.60 % of the drug was not recovered)

Notice that the concentration went up (0.25 → 0.462 mg/mL) while the recovery is below 100 %: the extract was made up to half the original volume. Recovery compares amounts, never concentrations. Whether 92.40 % is acceptable depends on the procedure — the criteria come from your practical manual or validated method, not from this number alone.

Common mistakes

Dividing the two concentrations instead of the two amounts. If the final volume differs from the initial volume, C₂ / C₁ is not the recovery — multiply each concentration by its own volume first.

Using the concentration read in the cuvette without correcting for the dilution made before measuring it. C₂ must be the concentration of the whole recovered solution.

Mixing units silently — for example taking 250 µg/mL and 0.462 mg/mL as if they were the same unit, which makes the recovery 1000 times wrong.

Weighing a crystallised or extracted product before it is dry. Residual solvent or water adds mass and can push the result above 100 %.

Confusing recovery with yield. Recovery compares the same substance before and after a step; percentage yield compares a reaction product with its theoretical amount from the limiting reactant.

Assumptions and limitations

Concentration × volume assumes each concentration applies uniformly to the whole volume entered with it (a well-mixed solution).

A mass and a volume cannot be compared without the material's density, and IU cannot be turned into a mass without substance-specific data, so the calculator refuses those pairings rather than guessing.

Recovery shows how much was lost or found, not why. It cannot tell transfer losses from degradation or incomplete extraction.

Acceptance limits are not built in: they depend on the procedure and are set by the method protocol, SOP or pharmacopoeial monograph.

Guide: Accuracy, Precision and Percentage Recovery in Pharmaceutical AnalysisThe concept in full, with practice questions.Accuracy & % Recovery CalculatorFor spike-recovery studies with replicate trials: mean recovery, SD and %RSD.Percentage Yield CalculatorWhen the product is formed by a reaction rather than recovered unchanged.Dilution Calculator (C₁V₁ = C₂V₂)To work out the dilution between your recovered solution and the cuvette.

References

International Council for Harmonisation. ICH Q2(R2): Validation of Analytical Procedures. Step 4, adopted 1 November 2023. Source
United States Pharmacopeia–National Formulary. General Chapter <1225> Validation of Compendial Procedures. Rockville (MD): USP.
Stockton SJ. Stoklosa and Ansel's Pharmaceutical Calculations. 16th ed. Philadelphia: Wolters Kluwer; 2021.

Common questions

On paper it often is. A product that is not fully dry still holds solvent or water; an extract can carry co-extracted impurities that add weight or absorbance; a pipetting or dilution error, or a drifting calibration curve, inflates a measured concentration. A result above 100% is a signal to re-check the data, not proof that something was created.

Recovery compares the amount of the same substance before and after a step — you started with 2.00 g of crude aspirin and got 1.64 g back. Percentage yield compares the product you isolated with the theoretical amount a reaction could form from its limiting reactant.

A known amount of the analyte is added (spiked) to a blank or sample matrix and then measured with the method. The found amount as a percentage of the added amount shows how accurate the method is in that matrix. Acceptance limits come from the validation protocol or the applicable guideline.

A mass and a volume are different quantities; converting between them needs the density of that specific material. Convert one of them first (mass = volume × density), then enter both as masses.

Yes, as long as both values use it — for example a labelled 100% content and a found 98.7%, or 10,000 IU added and 9,640 IU found. IU cannot be converted to a mass without substance-specific information, so it is never mixed with other units.

Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy