What is a compounding ratio?

A compounding ratio expresses how much of each ingredient is needed relative to the others. For example, a 1:2:7 formula means ingredient A is 1 part, B is 2 parts, and C is 7 parts — totaling 10 parts. Each ingredient's final quantity equals (its parts / total parts) × batch size.

Can I enter percentage concentrations instead of ratio parts?

Yes. Enter the percentage value for each ingredient (e.g., 5, 10, 85) and set the total to 100. The calculator treats them identically since percentages are just parts-per-hundred.

Does this calculator account for overfill or beyond-use dating?

No — this tool only calculates proportional scaling. Overfill, excipient adjustments, and beyond-use dating require professional judgment and are not automated here.

What units does the batch size support?

The tool is unit-agnostic. Enter the batch size in any unit (g, mg, mL, oz) and results are expressed in the same unit. Ensure all ingredients share the same unit system for a valid formula.

How do I handle a formula where parts do not add up to a round number?

Enter the exact parts for each ingredient. The calculator sums them automatically for the denominator, so there is no requirement that they total 100 or any other round number.

Compounding Ratio Calculator

Enter your compound formula ingredients with their ratios and a target batch size to get the exact quantity needed for each ingredient.

Formula Ingredients

Batch Size

Unit

Scaled Quantities

Add ingredients and click Calculate

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Summary

This calculator proportionally scales a ratio formula to a target batch size. Enter each ingredient name and ratio value; the denominator is calculated automatically from the sum of the parts. The output checks arithmetic only, not potency, compatibility, stability, or the suitability of a medication formula.

How it works

Add each ingredient in your formula with its name and ratio value.
The calculator automatically sums the ratio values to obtain the denominator.
Specify your target batch size and unit (grams, milligrams, mL, etc.).
The calculator divides the target batch proportionally across all ingredients.
Copy or print the scaled formula for dispensing.

Use cases

Scaling a topical cream formula from a 30 g base to a 100 g batch.
Calculating quantities for a multi-ingredient capsule compound.
Converting a veterinary compound formula to a different fill weight.
Verifying ingredient proportions before a compounding run.
Teaching pharmacy students how ratio-based compounding math works.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu