How to use the dose by weight calculator
Prepare the values for this calculation
Multiply an already-prescribed weight-based dose by an entered body weight. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Prescribed dose (mg/kg): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Body weight (kg): enter a value at least 0.001 and no more than 500. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Calculated total dose first. With the unchanged example inputs, it is 350 mg. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Prescribed dose (mg/kg) from 5 to 5.5. The resulting Calculated total dose is 385 mg. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Dose by Weight Calculator formula
Total calculated dose (mg)=prescribed dose (mg/kg)×weight (kg).
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Prescribed dose (mg/kg) | minimum 0 | 5 |
| Body weight (kg) | minimum 0.001; maximum 500 | 70 |
Worked example
Using the example inputs above, the calculated total dose is 350 mg.
- Calculated total dose
- 350 mg
- Prescribed factor
- 5 mg/kg
- Entered weight
- 70 kg
Results and assumptions
Calculation check only. Use the prescribed/ordered quantity and the exact product/tubing label. Independently verify medication and infusion calculations with a qualified clinician or pharmacist before administration. This page does not calculate or recommend the prescribed mg/kg value.
Sources and method references
Fix an input or unexpected result
Prescribed dose (mg/kg) is required. Enter prescribed dose (mg/kg) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.