Dosage Calculator — Medical Dosing

Use the Dosage Calculator

This dosage calculator is a practical medical calculator for converting mg/kg guidance into per‑dose and daily totals. It’s a clinician‑friendly clinical calculator that also returns mL or tablets.

Start your dosing math

How to Use Dosage Calculator — Medical Dosing

1. Step 1: Enter weight

   Type weight in kg or lb, then choose Metric or US.

2. Step 2: Pick dosing mode

   Select mg/kg per dose or mg/kg per day and set doses/day.

3. Step 3: Add details

   Enter the mg/kg value. Optionally add max caps, concentration (mg/mL) or tablet strength (mg/tablet).

4. Step 4: Calculate dose

   Tap Calculate to see mg per dose and total daily mg with rounded mL or tablets.

5. Step 5: Review schedule

   Pick a start time to generate evenly spaced dose times for the day.

Key Features

• Per‑kg per‑dose and per‑day dosing
• US/Metric weight with quick unit swap
• Max per‑dose and max daily caps
• Liquid (mg/mL) and tablet strength support
• Rounded mL or half‑tablet suggestions
• Auto‑generated daily schedule

Understanding Results

Formula

If guidance is stated as mg/kg per dose, the calculation is: per‑dose mg = (weight in kg) × (mg/kg per dose). If guidance is mg/kg per day, first compute the daily total: daily mg = (weight in kg) × (mg/kg per day), then split by doses per day to get per‑dose mg. Optional caps can limit the per‑dose amount and/or the total daily amount.

Reference Ranges & Interpretation

Medication dosing varies by drug, indication, age, and clinical status. Package inserts and trusted references list typical ranges (often a low–high mg/kg window) plus maximums. When you supply a concentration (mg/mL), the tool converts mg per dose into milliliters; with tablet strength (mg/tablet), it estimates whole or half tablets. Always compare the result with the official source and consider patient‑specific factors such as renal or hepatic function.

Assumptions & Limitations

This calculator does not select a drug or recommend a dose. It only translates a dose you provide into practical per‑dose and per‑day amounts. It assumes the entered values are appropriate for the patient. For renally cleared medications, see dose adjustments after estimating kidney function. When in doubt, consult a pharmacist or clinician and the current medication label.

Complete Guide: Dosage Calculator — Medical Dosing

Use our dosage calculator to convert mg/kg into per-dose and total daily amounts. Add concentration or tablet strength to get mL or tablets with a schedule.

What the dosage calculator solves

Real‑world medication instructions are often stated as a range (for example, “10–15 mg/kg per dose” or “30 mg/kg per day in divided doses”) with additional notes like a maximum single dose and maximum daily dose. Converting that guidance into practical numbers for a specific weight takes a few steps: compute the milligram amount, check caps, and, if needed, convert into mL or tablets. Our dosage calculator makes this translation fast, consistent, and transparent so you can focus on clinical decision‑making.

The tool does not select a drug or recommend a dose. Instead, it helps you apply a dose you already have in mind, or one stated in a trusted reference, to an individual. If you need body‑surface‑area dosing, try the BSA calculator and then apply a label’s mg/m² guidance.

How it works (mg/kg and caps)

Provide weight in kilograms (or pounds with quick conversion), select whether the instruction is stated as mg/kg per dose or mg/kg per day, then enter the number of doses per day. The calculator multiplies weight by the mg/kg value to find either the per‑dose milligrams (if “per dose” is chosen) or the daily total (if “per day” is chosen). Optional caps let you limit the result to a maximum per‑dose and/or a maximum daily total.

If you add a liquid concentration (mg/mL), the tool converts per‑dose milligrams into milliliters and rounds to a sensible increment such as 0.1 mL. If you add a tablet strength (mg/tablet), the tool estimates tablets per dose using half‑ or quarter‑tablet rounding. The summary includes both the calculated value and the rounded practical value.

mg/kg per dose vs mg/kg per day

Clinicians encounter both formats. With mg/kg per dose, each administration is calculated directly: multiply weight (kg) by the mg/kg value, then give that amount each time. With mg/kg per day, first compute the total daily milligrams and then split by the number of doses per day. The total daily amount remains the same; only the per‑dose amount changes based on dosing frequency.

Regardless of format, always compare against official maximums. In pediatric care especially, a label may specify a high‑end daily cap even when the mg/kg calculation would exceed it. Our tool accepts both a per‑dose maximum and a daily maximum and shows when a cap reduces the calculated number.

Liquids vs. tablets (mL and tablets per dose)

Liquid medicines list a concentration such as 160 mg/5 mL or 100 mg/mL. Entering the concentration lets the calculator convert a milligram dose into an easily measured volume. You can select a rounding increment (for example, 0.1 mL or 0.5 mL) to match your measuring device. For solid oral dosage forms, enter a tablet strength (e.g., 200 mg/tablet). The calculator displays the exact calculated count and a practical suggestion rounded to half or quarter tablets when appropriate.

If both a concentration and a tablet strength are entered, the tool shows both conversions so you can compare. For infants and small children, volumes are often clearer than fragments of tablets. For adults, tablet counts may be more convenient. Use clinical judgment and the product’s label to decide which form is appropriate.

Scheduling doses across the day

Adherence improves when dosing times are predictable and easy to remember. After calculation, pick a start time and the tool will evenly space the remaining administrations across 24 hours. If a drug has a specific interval (e.g., every 6 hours), choose the corresponding number of doses per day to match that interval. Consider meals, sleep, and school or work schedules when setting the start time.

For drugs with short half‑lives or narrow therapeutic windows, consistent spacing can be especially important. To explore how a medication’s half‑life shapes timing, try our drug half‑life calculator. For opioids and pain management, you can also model conversions using theopioid conversion calculator ormorphine equivalent calculator.

Adjustments: renal, hepatic, age

Many medications require dose adjustments in kidney or liver impairment. This calculator does not perform those adjustments automatically. Estimate kidney function (e.g., eGFR or creatinine clearance) and then consult the product label to determine a revised dose or interval. Our eGFR calculator can help quantify renal function before you apply dose reductions. For adult weight‑based dosing, body composition can affect drug handling; when needed, calculate ideal or adjusted body weight first and use that value for mg/kg.

Pediatric dosing is often weight‑based with strict caps. If you need a pediatric‑focused workflow, thepediatric dose calculator provides a child‑friendly experience and reminders about formulation and measuring devices. For high‑variability biologics or chemotherapy, dosing may scale by body surface area; use theBSA calculator first, then apply mg/m² per protocol.

Common pitfalls and double‑checks

The most frequent cause of dosing errors is a unit mismatch. Double‑check that weight is in kilograms when entering mg/kg values. Confirm the liquid concentration’s units (mg/mL versus mg/5 mL) and normalize as needed. Beware decimal placement: 1.0 mL is ten times 0.1 mL. When the calculator’s cap reduces a calculated value, confirm you are referencing the correct maximums for the patient’s age and indication.

For insulin or titrated therapies where frequent adjustments are expected, consider using disease‑specific tools like the insulin calculator for a tailored approach. When you need a quick sanity check on weight‑based dosing, a general mg to mL dose calculator can help confirm liquid conversions.

Worked examples

The following examples are illustrative only. They are not clinical recommendations. Always consult a current, authoritative source such as a package insert or a trusted clinical database.

Example A — mg/kg per dose: Suppose a label suggests 10 mg/kg per dose given twice daily, maximum 400 mg per dose, maximum 1,200 mg per day. For a 25‑kg child: per dose mg = 25 × 10 = 250 mg; daily mg = 250 × 2 = 500 mg. Caps are not hit. If the liquid is 100 mg/mL, per dose volume is 2.5 mL; rounded to 0.1 mL, that’s 2.5 mL.

Example B — mg/kg per day: A guideline states 30 mg/kg per day in three divided doses, maximum 1,000 mg/day. For a 50‑kg adult: daily mg = 50 × 30 = 1,500 mg. The daily cap reduces this to 1,000 mg/day. Per dose = 1,000 / 3 ≈ 333 mg. With 200 mg tablets, the exact is 1.67 tablets per dose; rounded to half‑tablets, 1.5 tablets (300 mg) or 2 tablets (400 mg) depending on clinical judgment and labeling.

Example C — checking intervals: If a drug must be given every six hours, choose four doses per day and set the start time to a practical anchor such as 06:00, then follow the schedule. When the interval must be exact, avoid ad hoc “wake‑hour” spacing and keep the 24‑hour split.

Related tools

• Pediatric Dose Calculator — child‑friendly workflow and reminders.
• eGFR Calculator — quantify renal function before dose adjustments.
• BSA Calculator — for mg/m² dosing protocols.
• Drug Half‑Life Calculator — understand timing and accumulation.
• Opioid Conversion Calculator — switch safely between agents.
• Insulin Calculator — adjust dose planning for diabetes care.

Browse all tools on the calculators index or explore more in theClinical & Medications category.

Using the dosage calculator step by step

1) Select units and enter the patient’s weight. If you know pounds, choose US/Imperial and the tool converts to kilograms internally. 2) Pick the dosing mode (mg/kg per dose or per day) and set how many times a day the medicine is given. 3) Enter the mg/kg value from your reference. 4) Add optional caps if your source states a maximum per dose and a maximum per day. 5) If you have a liquid, enter mg/mL to get mL per dose; if you have tablets, enter mg/tablet to see the tablet count per dose. 6) Tap Calculate and review the result and schedule.

The result cards summarize capped per‑dose and daily values in milligrams. If you entered a concentration or tablet strength, you will also see practical equivalents. Each administration is listed in the schedule with a time and the per‑dose milligrams. You can copy the mobile summary to share or note for personal use.

Rounding rules and practical measurement

Rounding should make a dose easier to measure without meaningfully changing exposure. For liquids, a 0.1 mL step is appropriate when using oral syringes with 0.1 mL markings. For thicker suspensions or home use with larger syringes, 0.2–0.5 mL may be a better choice. For tablets, half‑tablet rounding is common when the product is scored; quarter‑tablets should be used only when labeling or professional guidance supports it and the tablet can be split accurately.

Always confirm that the formulation you have matches the reference (for example, immediate‑release vs extended‑release). A dose intended for once‑daily extended‑release tablets may be unsafe if split into multiple doses or if crushed. Consult the package insert or a trusted database for formulation‑specific cautions.

Choosing the right measuring device

For liquid medicines, oral syringes provide the most reliable measurements. Household spoons vary widely in volume and can lead to under‑ or overdosing. Use a device that matches the rounding you selected. For example, if the calculator displays 2.4 mL per dose and you chose 0.1 mL rounding, provide a 5 mL oral syringe with 0.1 mL markings. Many pharmacies can supply appropriate syringes with clear instructions.

Adjusted, ideal, and dosing body weight

Some medications specify dosing by ideal body weight (IBW) or adjusted body weight (AdjBW), particularly in obesity where drug distribution differs. If your reference states IBW or AdjBW, compute that weight first and then enter it here. See theAdjusted Body Weight andIdeal Body Weight calculators.

Quality and safety checklist

• Weight verified in kilograms (kg), not pounds.
• Correct mg/kg value taken from a current, authoritative source.
• Per‑dose and per‑day caps checked and applied when applicable.
• Liquid concentration confirmed (mg/mL vs mg/5 mL) and rounded to a device‑appropriate step.
• Tablet strength, scoring, and ability to split verified per labeling.
• Formulation (IR vs ER) confirmed; schedule matches required interval.
• Renal/hepatic considerations reviewed; adjustments applied where needed.
• Potential interactions reviewed; patient counseling provided.

Units, abbreviations, and decimals

Stick to SI units: kilograms (kg), milligrams (mg), milliliters (mL). Avoid ambiguous abbreviations such as “U” (units) that can be misread; write “units” in full if using insulin. Use leading zeros for values below one (0.5 mL, not .5 mL) and avoid trailing zeros when unnecessary (2 mg, not 2.0 mg). The calculator accepts commas or periods as decimal separators and normalizes input safely.

More worked examples

Example D — concentration normalization: A bottle lists 160 mg/5 mL. Normalize to 32 mg/mL and enter 32 under concentration. If the dose per administration is 240 mg, the volume is 240 / 32 = 7.5 mL. With 0.5 mL rounding, that remains 7.5 mL.

Example E — cap interaction: A reference says 15 mg/kg/day divided twice daily, max 1,000 mg/day, max 600 mg/dose. For a 90‑kg adult, daily mg = 90 × 15 = 1,350 mg, reduced to 1,000 mg/day by the daily cap. Per dose = 1,000 / 2 = 500 mg, also under the per‑dose cap of 600 mg. If the tablet is 250 mg, the exact is 2 tablets per dose.

Example F — tablets and rounding: A label calls for 12 mg/kg per dose every eight hours (three times daily), with 200 mg tablets that can be split. For a 42‑kg patient, per dose mg = 42 × 12 = 504 mg. With half‑tablet rounding, 2.5 tablets (500 mg) is practical and within typical tolerance.

Light references and further reading

For current drug information, rely on manufacturer labeling and trusted, non‑commercial references. Many countries host official online label libraries. In the United States, you can search DailyMed for package inserts and updates.

Scenarios and decision patterns

Analgesics and antipyretics: OTC products for pain and fever are often dosed by weight with clear daily caps. The calculator helps translate mg/kg into mL or tablets, but final choices depend on formulation and patient‑specific factors (age, comorbidities, and concurrent medicines). When labeling provides a child dosing chart, follow the chart first and use the tool for transparency and double‑checking.

Antibiotics: Many oral antibiotics provide ranges (e.g., 20–40 mg/kg/day). Choose a value within the range according to severity and source guidance, then enter it as mg/kg per day. Apply daily caps if present. Remember that dosing intervals matter for pharmacodynamics; ensure the number of daily doses matches the intended interval.

Time zones and adherence: When crossing time zones, even spacing is disrupted. Consider a temporary bridging schedule; then resume the original spacing at the destination’s clock time. For sleep/wake rhythm planning, the jet lag calculator can suggest timing strategies that make adherence easier.

Missed doses: Many labels advise taking a missed dose as soon as remembered unless it is close to the next dose; never double up unless explicitly instructed. Because the calculator spreads doses evenly across 24 hours, you can quickly see remaining times and decide—per label guidance—how to proceed.

Communication: For caregivers, provide plain‑language instructions and avoid ambiguous abbreviations. Include both the per‑dose amount (mg and mL or tablets) and the exact times. A printed or electronic dosing schedule reduces errors and improves confidence.

Educational use only. Not a substitute for professional medical advice. Always consult the latest manufacturer labeling and standard references such as the package insert or a trusted clinical database.

Frequently Asked Questions