Theoretical Yield Calculator
The maximum product mass from the balanced equation and the limiting reagent.
What is Theoretical Yield?
The theoretical yield is what the balanced equation promises from the limiting reagent: the ceiling no real experiment reaches. It is the limiting-reagent calculation read differently — the same smallest-quotient argument finds the run's limit, and the product side of the equation converts that into moles and grams. The number is useful precisely because it is never attained; the percent-yield tool sits downstream to compare it with what the lab actually got.
How it works
The equation is balanced first, each reactant's moles are divided by its coefficient, and the smallest quotient is the limiting one — the same engine the limiting-reagent page uses. Each product's moles are that quotient times its coefficient, and the molar mass converts to grams. All products are listed, since the limiting reagent sets every one of them at once.
- Enter what you know. Every field recalculates as you type — there is no submit button. Leave the quantity you want blank and the page solves for it.
- Read the answer and the working. The result appears above the fold; underneath it is the formula with your numbers substituted, so the arithmetic can be checked rather than trusted.
- Check the units and the size. Units are shown on every value and selectable per field, so a result in kJ, kPa or km/h is converted rather than assumed. Sanity-check the magnitude against a known landmark such as 1 g/cm³ for water.
Examples
A textbook problem with a known answer
Every tool here is checked against standard example problems — the molar mass of C6H12O6 is 180.16 g/mol, and free fall from 20 m takes about 2.02 s at g = 9.8 m/s².
A result you want to reason backwards from
Leave the quantity you already know blank instead: given the final answer, most tools recover the starting value — the mass needed for a target concentration, or the height a fall must have had.
Common mistakes
Forgetting that a formula is only as good as its subscripts
H2O and H2O2 are different compounds. The formula field shows its parse — element by element — so a mis-typed subscript is visible before it reaches the arithmetic.
Mixing units in the middle of a calculation
The most common source of a wrong answer is a value in grams next to a formula expecting kilograms, or Celsius next to a gas constant expecting kelvin. This category converts on the way in and labels what it used.
Frequently asked questions
Is theoretical yield the same as limiting reagent?
No — the limiting reagent is the input that runs out first; the theoretical yield is the output amount it permits. One reaction, one limiting reagent, one ceiling; the pages share the engine but answer different questions.
Why is the theoretical yield never reached?
Side reactions, equilibrium back-reaction, product lost in transfers and purification, product still wet when weighed. Real yields run 50–95% for ordinary lab work; the gap between the ceiling and the scale is the percent yield.
Can I enter grams instead of moles?
Enter moles of each reactant here; the tool converts them to grams on the product side where the molar mass belongs. For grams in, convert first with the Grams to Moles Converter — that single step is where most wrong yields start.