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MedTestBankDosage Calculation for Nursing

Reconstitution dosage calculation practice problems

Dosage calculation practice for nursing students: solve unlimited new problems below with instant checking, or work through the 15 problems with answers further down.

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Formula to use

mL = desired dose ÷ concentration after reconstitution (mg/mL)

Full doses in the vial = total drug ÷ dose ordered (round down)

Open the reconstitution for powdered medications calculator to check your own numbers step by step.

15 practice problems with answers

Solve each problem on paper first, then open the answer to compare every step.

  1. A vial contains 1 g of an antibiotic powder. The label says: add 2.1 mL of sterile water to obtain 350 mg/mL. The order is 500 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (350 mg/mL), not the diluent volume.
    2. 500 mg ÷ 350 mg/mL = 1.429 mL, rounded to 1.4 mL.

    Answer: 1.4 mL

  2. A vial contains 1 g of an antibiotic powder. The label says: add 3.4 mL of sterile water to obtain 250 mg/mL. The order is 250 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (250 mg/mL), not the diluent volume.
    2. 250 mg ÷ 250 mg/mL = 1 mL, rounded to 1 mL.

    Answer: 1 mL

  3. A vial contains 1 g of an antibiotic powder. The label says: add 3.4 mL of sterile water to obtain 250 mg/mL. The order is 750 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (250 mg/mL), not the diluent volume.
    2. 750 mg ÷ 250 mg/mL = 3 mL, rounded to 3 mL.

    Answer: 3 mL

  4. A vial contains 1 g of an antibiotic powder. The label says: add 2.5 mL of sterile water to obtain 330 mg/mL. The order is 500 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (330 mg/mL), not the diluent volume.
    2. 500 mg ÷ 330 mg/mL = 1.515 mL, rounded to 1.5 mL.

    Answer: 1.5 mL

  5. A vial contains 2 g of an antibiotic powder. The label says: add 4.2 mL of sterile water to obtain 400 mg/mL. The order is 400 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (400 mg/mL), not the diluent volume.
    2. 400 mg ÷ 400 mg/mL = 1 mL, rounded to 1 mL.

    Answer: 1 mL

  6. A vial contains 1 g of an antibiotic powder. The label says: add 2.5 mL of sterile water to obtain 330 mg/mL. The order is 660 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (330 mg/mL), not the diluent volume.
    2. 660 mg ÷ 330 mg/mL = 2 mL, rounded to 2 mL.

    Answer: 2 mL

  7. A vial contains 1 g of an antibiotic powder. The label says: add 3.4 mL of sterile water to obtain 250 mg/mL. The order is 500 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (250 mg/mL), not the diluent volume.
    2. 500 mg ÷ 250 mg/mL = 2 mL, rounded to 2 mL.

    Answer: 2 mL

  8. A vial contains 2 g of an antibiotic powder. The label says: add 4.2 mL of sterile water to obtain 400 mg/mL. The order is 2,000 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (400 mg/mL), not the diluent volume.
    2. 2,000 mg ÷ 400 mg/mL = 5 mL, rounded to 5 mL.
    3. More than 3 mL: split the dose between two IM sites or check with the pharmacist, as your facility directs.

    Answer: 5 mL

  9. A vial contains 2 g of an antibiotic powder. The label says: add 4.2 mL of sterile water to obtain 400 mg/mL. The order is 1,000 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (400 mg/mL), not the diluent volume.
    2. 1,000 mg ÷ 400 mg/mL = 2.5 mL, rounded to 2.5 mL.

    Answer: 2.5 mL

  10. A vial contains 1 g of an antibiotic powder. The label says: add 2.1 mL of sterile water to obtain 350 mg/mL. The order is 350 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (350 mg/mL), not the diluent volume.
    2. 350 mg ÷ 350 mg/mL = 1 mL, rounded to 1 mL.

    Answer: 1 mL

  11. A vial contains 0.5 g of an antibiotic powder. The label says: add 1.8 mL of sterile water to obtain 250 mg/mL. The order is 125 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (250 mg/mL), not the diluent volume.
    2. 125 mg ÷ 250 mg/mL = 0.5 mL, rounded to 0.5 mL.

    Answer: 0.5 mL

  12. A vial contains 1 g of an antibiotic powder. The label says: add 2.5 mL of sterile water to obtain 330 mg/mL. The order is 330 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (330 mg/mL), not the diluent volume.
    2. 330 mg ÷ 330 mg/mL = 1 mL, rounded to 1 mL.

    Answer: 1 mL

  13. A vial contains 1 g of an antibiotic powder. The label says: add 2.1 mL of sterile water to obtain 350 mg/mL. The order is 700 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (350 mg/mL), not the diluent volume.
    2. 700 mg ÷ 350 mg/mL = 2 mL, rounded to 2 mL.

    Answer: 2 mL

  14. A vial contains 0.5 g of an antibiotic powder. The label says: add 1.8 mL of sterile water to obtain 250 mg/mL. The order is 500 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (250 mg/mL), not the diluent volume.
    2. 500 mg ÷ 250 mg/mL = 2 mL, rounded to 2 mL.

    Answer: 2 mL

  15. A vial contains 0.5 g of an antibiotic powder. The label says: add 1.8 mL of sterile water to obtain 250 mg/mL. The order is 250 mg IM. How many mL will you withdraw?

    Show the answer
    1. Use the concentration after mixing (250 mg/mL), not the diluent volume.
    2. 250 mg ÷ 250 mg/mL = 1 mL, rounded to 1 mL.

    Answer: 1 mL