Percent Recovery Calculator
Percent recovery is the mass of pure material you collect after a purification step (recrystallization, extraction, or filtration) divided by the mass you started that step with, times 100. Unlike percent yield, it never involves a balanced equation or a stoichiometric theoretical yield, because no chemical reaction is happening, only physical separation and cleanup of material you already had.
What Percent Recovery Actually Measures
Percent recovery tracks how much material survives a purification step. You take an impure or crude solid or extract, run it through recrystallization, extraction, or filtration, and weigh what comes out clean on the other side. That final mass divided by the starting mass, times 100, is percent recovery.
This is a different question from percent yield, which asks how much product a chemical reaction produced compared to what a balanced equation predicts. Percent recovery asks a purification question: of the material that went into the beaker, how much did you get back in usable, purified form? No reaction, no stoichiometric formula, no limiting reagent. Just mass in, mass out.
The Percent Recovery Formula
Percent recovery = (mass recovered after purification / mass before purification) x 100. Both masses go in the same unit before you divide, since the ratio only means something when the units cancel cleanly.
The numerator is the mass of pure, dry material you collect after the purification step is finished, filtered, and dried to constant weight. The denominator is simply the mass of crude or impure material you weighed out before you started purifying it. Neither number comes from a chemical equation. Compare this with the theoretical yield used in percent yield calculations, where the denominator is calculated from moles of limiting reagent and a balanced equation, and the actual yield, which is the mass a reaction actually produced. Percent recovery skips all of that. The starting mass for percent recovery is whatever you weighed before purification, whether that came from a reaction, an extraction, or was simply crude material handed to you at the start of a lab.
Percent Recovery vs. Percent Yield, Side by Side
| Calculation | Numerator | Denominator | Balanced equation involved? |
|---|---|---|---|
| Percent yield | Actual yield: mass of product a reaction produced | Theoretical yield: mass predicted from moles of limiting reagent | Yes, always |
| Percent recovery | Mass of pure material recovered after purification | Mass of crude or impure material before purification | No, never |
The table is the whole point of this page. If a calculation involves a balanced equation, moles, or a limiting reagent, it is percent yield territory. If it involves weighing material before and after recrystallizing, extracting, or filtering it, with no reaction chemistry involved at all, it is percent recovery.
Typical Recovery Ranges for Recrystallization
Recrystallization always loses some material, because a small amount of the compound stays dissolved in the cold solvent even after crystals form, and more is lost on filter paper, in transfers, and in the wash. A well-chosen solvent pair, where the compound is quite soluble hot and only sparingly soluble cold, commonly recovers a large majority of the material. A poorly matched solvent, where the compound stays fairly soluble even in the cold solvent, or where too much wash solvent is used, can lose a much larger fraction and drop recovery well below what a textbook procedure would consider acceptable.
There is no single correct number here, and any specific percentage you see quoted as a hard rule should be treated as a rough classroom range rather than a measured constant. What matters is the direction: better solvent choice and gentler technique push recovery up, and harsh technique or the wrong solvent pushes it down.
Factors That Affect Recovery
- Solubility in the cold solvent. If the compound is still noticeably soluble in the ice-cold solvent, a meaningful fraction never crystallizes at all and stays behind in the filtrate.
- Cooling rate. Slow, controlled cooling favors large, well-formed crystals and better recovery. A rushed or overly aggressive cooling step can also encourage oiling out or trap solvent, which affects both recovery and the resulting percent purity of the sample.
- Wash solvent volume. Washing crystals removes surface impurities, but each rinse also dissolves a little of the product. More wash solvent means cleaner crystals but lower recovery.
- Number of transfers. Every time material moves between a flask, a filter, and a drying dish, a small amount sticks to the glassware and never makes it to the final weighing. More transfers, more product loss.
Worked Example 1: Straightforward Recrystallization
A student recrystallizes 2.00 g of crude solid from a hot solvent, cools it slowly, filters, dries the crystals, and weighs 1.60 g of pure product.
Percent recovery = (1.60 g / 2.00 g) x 100 = 80.0%. This is a reasonable recovery for a routine recrystallization: most of the material survived the purification, and the remaining 20% stayed dissolved in the cold mother liquor or was lost on the filter paper and glassware.
Worked Example 2: Extraction
An extraction workup starts with 5.00 g of crude extract. After separating layers, drying the organic phase, and evaporating the solvent, the purified product weighs 4.15 g.
Percent recovery = (4.15 g / 5.00 g) x 100 = 83.0%. The same formula applies regardless of which purification technique is used, extraction, recrystallization, or filtration; the numerator and denominator are still just masses before and after the physical cleanup step, not anything computed from a balanced equation.
Worked Example 3: A Poor-Recovery Case
A second student recrystallizes 3.00 g of the same crude solid but uses far more wash solvent than needed and lets the flask sit at room temperature instead of chilling it in an ice bath. The final dry product weighs only 1.20 g.
Percent recovery = (1.20 g / 3.00 g) x 100 = 40.0%. This low number is not a mystery once the technique is examined: without a proper ice-cold soak, more of the compound stayed dissolved in the mother liquor, and the heavy washing dissolved away additional product that had already crystallized. Neither of these problems shows up as a reaction going wrong, because there was never a reaction to begin with, only a purification step run poorly.
Frequently asked questions
What is percent recovery in chemistry?
Percent recovery is the percentage of material that survives a purification step, calculated as mass recovered after purification divided by mass before purification, times 100. It applies to recrystallization, extraction, and filtration, where the goal is cleaning up material you already have rather than running a chemical reaction. No moles or balanced equations are involved anywhere in the calculation.
How is percent recovery different from percent yield?
Percent recovery compares mass after a purification step to mass before it, with no chemical reaction involved. Percent yield compares the actual mass a reaction produced to a theoretical yield calculated from a balanced equation and moles of limiting reagent. If there is no reaction, it cannot be percent yield, no matter how similar the arithmetic looks.
What is a good percent recovery for recrystallization?
There is no fixed number, but a well-matched solvent pair and careful technique commonly recover a large majority of the crude material, while a poorly chosen solvent or rushed technique can lose much more. Any specific percentage quoted as a rule of thumb is a rough classroom range, not a universal measured constant, so judge recovery by technique, not by a memorized figure.
Can percent recovery exceed 100 percent?
Yes, and it almost always signals a problem rather than a bonus. Recovery above 100% usually means the recovered solid was not fully dried and still holds trapped solvent, or the balance was not tared correctly. It does not mean more pure material was created than you started with, since no reaction is generating new mass in a recovery calculation.
Does percent recovery need a balanced equation?
No, percent recovery never uses a balanced equation. It only needs two masses, before and after purification. This is the core difference from percent yield, which is impossible to calculate without a balanced equation to define the theoretical yield. If a problem gives you a reaction with reactants and products, that calculation is percent yield, not percent recovery.
What lowers recovery in recrystallization?
Recovery drops when the compound stays too soluble in the cold solvent, when cooling happens too quickly or unevenly, when too much wash solvent rinses away dissolved product, and when material is transferred between too many containers. Each of these loses a bit of product to the mother liquor, the wash, or the glassware rather than to any chemical side reaction.
How does solvent choice affect recovery?
Solvent choice is often the biggest factor in recovery. An ideal solvent dissolves the compound well when hot but only sparingly when cold, so most of the material crystallizes back out on cooling. A solvent that still dissolves the compound reasonably well even when cold leaves a larger fraction behind in the filtrate, lowering recovery regardless of how carefully the rest of the procedure is run.
Is percent recovery the same in extraction and recrystallization?
Yes, the formula is identical: mass recovered divided by mass before the step, times 100. Only the purification technique changes, recrystallization relies on solubility differences with temperature, extraction relies on solubility differences between two liquid layers, and filtration simply separates solid from liquid. The calculation itself does not care which physical method produced the two mass values.
Why did my recovery come out very low?
Very low recovery almost always traces to technique: too much wash solvent dissolving away product, a solvent choice where the compound stays soluble even cold, warm rather than ice-cold cooling before filtering, or repeated transfers between glassware that each leave residue behind. Check the solvent pair and cooling method first, since those two factors usually explain the biggest recovery losses.
How many recrystallizations should I do?
Enough to reach the purity you need, and no more, since each additional recrystallization improves purity but also lowers overall recovery. One recrystallization from a well-chosen solvent is often enough for a moderately impure solid, while a second recrystallization is used when the first pass leaves visible impurities or an off melting point, accepting the extra material loss in exchange for cleaner product.