Calculator
Formula & Notes
% w/w = (msolute / msolution) × 100
- msolution = msolute + msolvent.
- % w/w is temperature independent (mass-based), unlike % w/v or molarity which can vary with density.
- Round results appropriately for your application; this tool lets you choose decimal places.
FAQs
1) What does mass percent (w/w) mean?
It is the fraction of a solution’s total mass contributed by the solute, multiplied by 100. For example, 5% w/w means 5 g solute per 100 g total solution.
2) How do I compute it from lab data?
Weigh the solute, prepare the solution, weigh the final total mass, then compute (solute mass ÷ solution mass) × 100 using the first tab.
3) Can I solve backwards from a target percentage?
Yes. Use the second tab to find required solute for a known total mass and target %. Use the third tab to find the total mass for a given solute mass and target %.
4) Which units are supported?
Milligrams, grams, and kilograms. The calculator converts everything to grams internally and reports answers in the unit you select.
5) Is % w/w affected by temperature?
Mass-based percentages are largely temperature independent. However, ensure the sample is dry and stable to avoid mass drift.
6) What if my solution mass is less than the solute mass?
That’s not physically valid for a true solution. The tool will warn you; please check your measurements and ensure the solution mass includes both solute and solvent.
7) Can I use this for mixtures other than solutions?
Yes. The definition applies to any mixture where masses are additive and well defined (e.g., solid blends). Interpret results within your system’s context.