A percent w/w states ingredient mass per total solution mass. To express that ingredient per milliliter, you must also know the density of the complete solution at relevant conditions.

Worked example

A confirmed 5% w/w solution has 5 g ingredient per 100 g whole solution. At an explicitly measured 1.1 g/mL solution density, that is 0.05 × 1.1 × 1,000 = 55 mg/mL.

Confirm the percent basis first

NIST distinguishes mass fraction, ingredient mass divided by whole-mixture mass, from mass concentration, ingredient mass divided by solution volume. This page converts only confirmed w/w mass percent. It cannot interpret an ambiguous percent symbol on a product label.

Density belongs to the whole solution

Use measured or documented whole-solution density at the relevant composition and temperature, not the pure ingredient’s density. An assumed 1 g/mL can materially change the result. The separate percent-to-mg/mL tool handles confirmed w/v percent and does not need density.

Arithmetic, not a dosing instruction

The 5 mL line is a unit illustration based on the entered concentration, not a suggested amount. No dose, route, regimen or medical suitability is selected. For medicines, confirm the exact label and any intended amount with a clinician or pharmacist.

Explore the related calculation

For a different starting point, try the confirmed w/v percent converter or return to the main calculator. Browse the complete tool directory for this site.

Reference and corrections

The definitions and assumptions above follow these sources; the examples and calculator arithmetic are original to this page.

www.nist.gov reference

Found a problem? Email contact@mgtoml.app.

Percent w/w to mg/mL calculator

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