Conversion Percentage Calculator

Select an input basis, fill the required fields, then calculate conversion. Your result appears above this form.

Examples are illustrative; your experiment may include volume changes, side reactions, or measurement noise.

Conversion of a reactant A measures the fraction of A that reacts relative to its initial amount:

• X_A = (N_A0 − N_A) / N_A0
• % Conversion = 100 × X_A

This calculator supports different measurement bases by converting everything to moles:

• N = C × V (concentration basis; mol/L and L)
• N = m / M (mass basis; grams and g/mol)
• X = (F₀ − F) / F₀ (flow basis; single-pass conversion)
• If you measure product formed, infer reacted A using stoichiometry: N_A,reacted = (ν_A/ν_P) × N_P,formed, then X = N_A,reacted/N_A0.

Conversion as a key KPI

In reaction development, conversion links raw measurements to decision-ready performance. If n0 is 2.50 mol and n is 0.60 mol, X equals 0.76 and the conversion is 76.00%, showing most reactant has been consumed. Tracking conversion across runs helps separate kinetic limitations from feed variability and identifies when additional residence time or catalyst loading is justified. Many teams flag low conversion below 20%, moderate between 20% and 70%, and high above 70% for fast triage.

Selecting the measurement basis

Laboratory data rarely arrives as neat mole counts. This calculator supports concentration-volume, mass-molar-mass, flow, and product-based estimates, then normalizes everything to moles for consistent reporting. For example, C0 of 1.50 mol/L to 0.40 mol/L at 2.00 L gives n0 of 3.00 mol and n of 0.80 mol, again yielding 73.33% conversion, matching the same physical outcome.

Stoichiometry and side products

When product is measured directly, stoichiometric coefficients convert product formed into reactant reacted. If 3P forms from 2A, then 0.30 mol P implies 0.20 mol A reacted. Conversions above 100% typically indicate incorrect coefficients, analytical interference, or unaccounted parallel reactions that produce the same measured product signal.

Batch versus flow interpretation

Batch conversion usually compares initial charge to the amount remaining at a sampling time, so sampling delay matters. Single-pass flow conversion uses inlet and outlet molar flow rates, often under steady state. A reactor with F0 of 0.20 mol/s and F of 0.05 mol/s has 75% conversion, but the same number can represent very different selectivity depending on residence time distribution.

Data quality and uncertainty

Conversion is sensitive to small absolute errors when n0 is small. A ±0.01 mol uncertainty on n at n0 of 0.10 mol shifts conversion by about ±10 percentage points. Record the analytical method, calibration date, and dilution factors in notes, and use clamping only for presentation; warnings are better for troubleshooting.

Reporting and comparability

To compare experiments, keep the basis consistent: same reactant definition, sampling protocol, and units. Exporting CSV enables quick aggregation of conversion percent, banding, temperature, and pressure across many runs, while a PDF snapshot preserves the exact inputs used for a report or audit trail. Fix the same decimal setting across studies to avoid rounding-driven noise. Internally.

1) What does conversion percentage represent?

Conversion percentage is the fraction of the initial reactant that has reacted, expressed as a percent. It is based on X = (initial − final) / initial, after converting your inputs to a consistent mole basis.

2) Can conversion be negative or above 100%?

Yes, if the final amount appears larger than the initial, conversion becomes negative. Values above 100% usually come from unit mistakes, stoichiometry errors, or noisy measurements. Use warnings to debug, or clamp for display.

3) Which input basis should I select?

Pick the basis that matches what you measured most directly: moles from balances, mass with molar mass, concentration with volume, flow rates for single-pass reactors, or product formed when reactant is hard to assay.

4) How does the concentration option handle volume changes?

The calculator converts concentration to moles using N = C × V. If you enter only one volume, it assumes the same volume for initial and final. Enter both V0 and V when evaporation, sampling, or dilution changes volume.

5) How is conversion calculated from product formed?

It estimates reactant reacted using stoichiometry: reacted A = (νA/νP) × product formed. Conversion is then reacted A divided by the initial reactant amount. This assumes product starts near zero and is measured reliably.

6) Why should I export CSV and PDF reports?

CSV helps you aggregate many runs in spreadsheets or databases, while PDF captures a fixed snapshot of inputs, conversion, and notes for lab notebooks, QA review, or audits. Exporting reduces transcription errors and improves traceability.