Unit Conversion

Strength Conversion Calculator

Converts a concentration between percentage, ratio strength (1:X), weight/volume, weight/weight and volume/volume — for compounding and reading labels.

Ratio Strength (1:X)

100.00001:100

This represents the concentration in ratio strength (1:x) format

Clinical application

Ratio strengths are often used for dilute solutions (e.g., epinephrine 1:1000).

Convert

Strength (Percentage (%))

The percentage, e.g. 0.9 for normal saline.

From format

To format

Mass unit

Used by the weight/volume and weight/weight formats.

Volume unit

Used by the weight/volume format.

Common pharmacy strengths

In every format

1 as percentage (%), with mg and mL.

Step 1 — as a percentage1.0000%

Percentage (%)1.0000%

Input

Ratio Strength (1:X)100.00001:100

Result

Weight/Volume (wv)10.0000mg/mL

Weight/Weight (ww)10.0000mg/mg

Volume/Volume (vv)1.0000vv

Reference

Common equivalents

1%1 g/100 mL

1:1001%

ratio

1 mg/mL0.1%

5%50 mg/mL

0.1%1 mg/mL

1:10000.1%

ratio

1:10,0000.01%

ratio

Percentage strengths

1% = 1 g/100 mL (wv)

1% = 1 g/100 g (ww)

1% = 1 mL/100 mL (vv)

For wv: % = (g solute/100 mL) × 100

Ratio strengths

1:X means 1 part in X parts total

1:1000 = 0.1%

1:10,000 = 0.01%

Convert to %: (1/X) × 100

Weight/volume

Common format: mg/mL

1 mg/mL = 0.1%

10 mg/mL = 1%

50 mg/mL = 5%

Step 1 — turn the input into a percentage:

ratio 1:X → % = (1 ÷ X) × 100
w/v → % = value ÷ (10 for mg, 10000 for g) × (1 for mL, 0.001 for L)
w/w → % = value ÷ (10 for mg, 10000 for g)
v/v → % = value × density

Step 2 — turn the percentage into the output format:

ratio → X = 100 ÷ %
w/v → % × (10 for mg, 10000 for g) × (1 for mL, 1000 for L)
w/w → % × (10 for mg, 10000 for g)
v/v → % ÷ density

Going through a percentage means each format needs only one rule in and one rule out. Results are shown to 4 decimal places; for a ratio the X is also rounded to a whole number in the unit label.

Guide: Dilution and Concentration CalculationsThe concept in full, with practice questions.

References

Stockton SJ. Stoklosa and Ansel's Pharmaceutical Calculations. 16th ed. Philadelphia: Wolters Kluwer; 2021.

Common questions

One part of drug in 1000 parts of preparation. For a solid in a liquid that is 1 g in 1000 mL — the same as 0.1% w/v or 1 mg/mL.

Multiply the percentage by 10. A 1% w/v solution holds 1 g per 100 mL, which is 1000 mg per 100 mL, or 10 mg/mL.

w/v for a solid dissolved in a liquid (most solutions), w/w for semisolids such as creams and ointments, and v/v for one liquid mixed into another, such as alcohol in water.

A volume percentage says nothing about mass until you know how heavy the liquid is. Multiplying by density turns millilitres of solute into grams, so it can be compared with the weight-based formats.

About this calculator

The same concentration can be written several ways: adrenaline as 1:1000, 0.1% or 1 mg/mL. Pharmacists move between these constantly when compounding, checking labels and diluting stock solutions. This tool converts each format to a percentage first, then into the format you need.

Use it when

Turning a ratio strength such as 1:1000 into a percentage or mg/mL

Checking how many mg/mL a percentage solution contains

Preparing a compounding record that states strength in another format

Compounding tips

Always verify the final concentration matches prescription

Use appropriate precision for balance measurements

Document all calculations in compounding record

Check before relying on it

Ratio strengths are dangerous to misread — confirm 1:1000 vs 1:10,000 before any injection

The mass unit and volume unit you choose change the w/v and w/w figures

Volume/volume conversions depend on the density you enter

Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy

Convert

In every format

Reference

Keep learning

References

Common questions