Percent Yield Calculator

Created by Jack Bowater
Reviewed by Bogna Szyk and Adena Benn
Last updated: Mar 24, 2023

Our percent yield calculator will help you to understand how to calculate the percent yield, as well as teach you the percent yield formula and the percent yield definition.

Finding the yield is an integral part of any kind of synthetic lab work as the percent yield equation turns your experimental yields into a representation of how successfully you carried out your reaction.

Hopefully, after reading this page, you will have an answer to the questions "what is percent yield?" and "how to find percent yield?"

Percent yield definition

What is the percent yield? The percent yield definition is that it is a measure of the effectiveness of a synthetic procedure. Wordy, right? Simply put, percent yield tells you how well you carried out your reaction. If you were very careful with your reaction, made sure every molecule reacted and that nothing was lost when you poured the solution from one beaker to another, your percent yield would be $100\%$ (don't worry if you don't get $100\%$, this is practically impossible). If you accidentally poured your reaction mixture down the drain and lost everything, then your percent yield would be $0\%$, and if you still had a lot of your solvent present with the product, your yield would be greater than $100\%$. Still confused about how to find the percent yield? Check the percent yield equation below!

A percent yield of $100\%$ corresponds to the theoretical yield: discover this quantity with the theoretical yield calculator.

Percent yield formula

We can find percent yield can be found using the percent yield equation. It is expressed as a simple percentage calculated by using the experimental yield (we learned how to calculate it with our actual yield calculator) of your product (i.e., how much of your product you made) and the theoretical mass of the product (i.e., the mass if not a single molecule was lost). The percent yield formula is:

$Y_{\text{p}} =\frac{m_{\text{p},\text{exp}}}{m_{\text{p},\text{th}}}\cdot 100,$

where:

• $Y_{\text{p}}$ — The percent yield;
• $m_{\text{p},\text{exp}}$ — The experimental mass of the product; and
• $m_{\text{p},\text{th}}$ — The theoretical mass of the product.

The percent yield equation requires you to know two of the three variables, but it doesn't matter which two! Like any equation, it can be rearranged to find the unknown, but there's no need to worry about this when you can use our smart calculator; just enter the two known variables and find the third.

How to calculate percent yield

As you may have guessed from the percent yield equation above, if you want to know how to calculate the percent yield, you need two things, your experimental yield, and the theoretical yield. Let's assume you have both values; how to find the percent yield?

🙋 You may need to find the mole or concentration of your reactants to find the theoretical yield: use our tools, the mole calculator and the concentration calculator.

1. First, make sure both weights have the same units (use our weight converter if you need some help 😉).
2. Take your experimental yield and divide it by the theoretical yield.
3. Multiply this value by $100$ to find the percent yield.

There you go. Not too complicated, right? Or you could use our percent yield calculator to calculate it easily and quickly. A note about the values obtained; a value above $100\%$ is possible but is due to solvent being present in the sample as well as your product. Dry your product thoroughly and re-weight it to get the true percent yield. Also, a value of 100% is impossible to achieve; there will always be some molecules that do not react or that are left on the side of the glassware. A value of $70\%$ or higher is acceptable!

Examples of yield calculations

Time for some examples. Let's say you are doing a nucleophilic addition reaction, forming hydroxyacetonitrile from sodium cyanide and acetone.

Let's ignore the solvents underneath the arrow; we reacted $5\ \text{g}$ of acetone with $2\ \text{g}$ of cyanide, giving a theoretical yield of $6.54\ \text{g}$ of hydroxyacetonitrile. Now we know that if we carry out the experiment and get $5.58\ \text{g}$ of hydroxyactenitrile, what is the percent yield?

• We know our experimental yield is $5.58\ \text{g}$, and our theoretical yield is $6.54\ \text{g}$. Let's use the percent yield formula from above: $Y_{\text{p}} =m_{\text{p},\text{exp}}/m_{\text{p},\text{th}}\cdot 100$ and fill in the fields:
$Y_{\text{p}} = \frac{5.58}{6.54} \cdot 100 = 85.3\%$

The percent yield is $85.3\%$. That was a pretty successful reaction! You should feel a bit more confident in calculating theoretical yield now. Let's try another example to bolster that confidence.

You react $8\ \text{g}$ of calcium carbonate with $9\ \text{g}$ of acetic acid, forming $4.35\ \text{g}$ of acetone. Nice! Now we do this reaction, but, unfortunately, we only get $1\ \text{g}$ of acetone. What is the percent yield?

• Our experimental yield is $1\ \text{g}$, and our theoretical yield is $4.35\ \text{g}$. Using the percent yield formula again gives us the following:
$Y_{\text{p}} = \frac{1}{ 4.35} \cdot 100 = 22.9\%$

Now that's not great. Don't be upset, though. There's plenty of time left in the lab session, so you can try again. This time you try really, really hard not to lose any of your reaction mixture, and you end up with a yield of $5.31\ \text{g}$. Well, that's much better than last time, so you carry out a percent yield calculation:

$Y_{\text{p}}= \frac{5.31}{4.35}\cdot 100 = 122.1\%$

Oh no! The percent yield is over $100\%$, meaning there is still some solvent in our product. This means we need to dry our product further, so let's do that. After re-weighing our product (this time with no solvent), we find it weighs $4\ \text{g}$. Let's calculate the percent yield:

$Y_{\text{p}}= \frac{4}{4.35}\cdot 100 = 92.0\%$

Fantastic! Now you should have a grasp on the basics of percent yield calculation and, with it, have the knowledge you need to make the most out of our website. Happy calculating!

FAQ

How do I calculate the actual yield given the percent yield?

To calculate the actual yield from the percent yield, you can use the following steps:

1. Use the formula for percent yield:

percent yield = (mass actual yield / mass theoretical yield) × 100%.

2. Rearrange to solve for the actual yield:

mass actual yield = (percent yield / 100%) × mass theoretical.

3. Substitute values and calculate the actual yield.

For instance, given a percent yield of 70%, and a theoretical yield of 5 g, we can calculate the actual yield as follows:

mass actual yield = (70% / 100%)× 5 g.
mass actual yield = 3.5 g

Can the percent yield be over 100%?

Yes. A percent yield value above 100% can occur due to solvent or other impurities present in the product or sample. Proper isolation and drying of the product are required to accurately measure the actual yield.

What's the difference between theoretical yield and actual yield?

Theoretical yield is the maximum amount of product that can be obtained from a chemical reaction, calculated based on the reaction's stoichiometry. Actual yield is the measured amount of product obtained from the reaction in the lab, and it's always expected to be lower than the theoretical yield due to factors like incomplete reactions, product loss, and impurities.

Is a percent yield of 100% possible?

No, in practice, it’s not possible to achieve a percent yield of 100%. Deviation below the theoretical yield is always expected due to factors such as impurities, incomplete reactions, and product loss. As a result, the actual yield will always be lower than the theoretical yield.

What's the actual yield, given a theoretical yield of 15 g?

Assuming a percent yield of 70%, the actual yield is 10.5 g. You can get this value by following these steps:

1. Use the formula for percent yield:

percent yield = (mass actual yield / mass theoretical yield) × 100%

2. Rearrange to solve for the actual yield:

mass actual yield = (percent yield / 100%) × mass theoretical

3. Substitute in the known values and calculate the actual yield:

mass actual yield = (70% / 100%) × 15 g
mass actual yield = 10.5 g

Jack Bowater
Theoretical yield
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Actual yield
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Percent yield
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