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Reconstitution Calculator

Reconstitution calculator works out Dose and Volume to give from Dose wanted (desired), Dose unit and Strength on hand (have). The default figures on this page give volume to give of 2.500 mL; change any entry and the result, the working and the sources update together.

Volume to give
2.500 mL
Medication Dosage Calculator
Dose
250.000 mg
Concentration
100.0000 mg/mL
Concentration
10.0000 % w/v
Total daily dose
250.000 mg
Final volume after reconstitution
10.000 mL
Calculation performed
Reconstitution
Worked out from United States Pharmacopeia, General Notices 8.140 - percentage concentrations: % w/v is grams of constituent per 100 mL of solution and 4 other sources.
Educational calculation only. Always verify every dose against the product label and your institution's policy before administering a medicine.

Your figures

Updates as you type
The amount of drug to be given in one dose.
The labelled amount of drug in the stock container or vial.
Used for weight-based dosing and for the maximum-dose ceiling.
The volume the dry powder itself occupies once dissolved, from the product label.
Used when a solution is labelled as a percentage, e.g. 1% lidocaine = 10 mg/mL.

How this is worked out

2 steps
  1. Final volume = 9.6 mL diluent + 0.4 mL powder displacement = 10 mL
  2. Concentration = 1000.0000000000001 mg / 10 mL = 100.00000000000001 mg/mL

Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed

Sources and references

5 sources

What the reconstitution calculator calculates

Converts between drug mass, solution concentration and volume: desired-over-have, mg to mL, mg/kg and mg/m² dosing, reconstitution, tablets per dose, days supply, mg/kg maximum dose and titration schedules.

How to use this reconstitution calculator

Enter Dose wanted (desired), Dose unit, Strength on hand (have) and Strength unit. Dose updates as you type. Change one figure at a time to see what drives the result.

How the result is worked out

Open “How this is worked out” beside the result for the step-by-step calculation behind Dose, Volume to give and Concentration.

The method follows United States Pharmacopeia, General Notices 8.140 - percentage concentrations: % w/v is grams of constituent per 100 mL of solution, Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098, Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 1916;17:863-871, MOUNJARO (tirzepatide) injection - FDA prescribing information, section 2 Dosage and Administration and NIST Special Publication 811 - exact unit conversions used for mass and volume.

What you can compare

Change one input at a time to see how it affects Dose, Volume to give and Concentration. The inputs you can vary are Dose wanted (desired), Dose unit, Strength on hand (have), Strength unit, Volume that strength is in (quantity) and Stock volume unit.

Understanding Dose, Volume to give and Concentration

Educational calculation only. Always verify every dose against the product label and your institution's policy before administering a medicine.

Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.

Embed this calculator on your website

Copy this code into any page. The calculator appears with the figures currently entered, sizes itself to fit, and a small credit line links back here. Free, no account, no ads inside it, no tracking of your readers. Set your own figures and fixed fields; Personal removes the credit line, sets your colour and shows you which sites use it.

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Frequently asked questions

How to calculate reconstitution?

Converts between drug mass, solution concentration and volume: desired-over-have, mg to mL, mg/kg and mg/m² dosing, reconstitution, tablets per dose, days supply, mg/kg maximum dose and titration schedules. Open “How this is worked out” beside the result to see each step for your own figures.

How to calculate peptide reconstitution?

It needs Dose wanted (desired), Dose unit, Strength on hand (have), Strength unit, Volume that strength is in (quantity) and Stock volume unit. Nothing else is required, and the figures stay in your browser.

What information do I need for the reconstitution calculator?

You need Dose wanted (desired), Dose unit, Strength on hand (have), Strength unit, Volume that strength is in (quantity), Stock volume unit, Volume given and Given volume unit. The page opens with default figures that give volume to give of 2.500 mL, so you can see the scale before entering your own.

What does this reconstitution calculator show?

It shows Dose, Volume to give, Concentration, Tablets per dose, Total daily dose, Body surface area, Final volume after reconstitution and Days supply, with the working and any warnings for your entries.

Can I check how the reconstitution calculator result was calculated?

Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.

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