Ashar Pervaiz28 October 2026Nursing Conversion Chart: The Units You Actually Use on Shift
Every metric conversion a nurse needs is the same rule applied four times: each step up the scale is a thousand. Micrograms to milligrams, milligrams to grams, grams to kilograms, millilitres to litres — all of them divide by 1,000 going up and multiply by 1,000 going down. The tables below cover that scale, the imperial measures that still appear on charts, the drip factors printed on giving sets, and the rate conversions that involve the number 60.
Keep it beside you rather than memorising it. If you want the arithmetic done for you, the unit conversion calculator handles the scale directly, and the dose calculator takes a weight-based order through to a dose.
Metric Weight: One Rule, Four Steps
This is the table that matters most, because drug strengths live here and the gaps between the rows are large.
| From | To | Do this | Example |
|---|---|---|---|
| Micrograms (mcg) | Milligrams (mg) | Divide by 1,000 | 500 mcg = 0.5 mg |
| Milligrams (mg) | Micrograms (mcg) | Multiply by 1,000 | 0.25 mg = 250 mcg |
| Milligrams (mg) | Grams (g) | Divide by 1,000 | 750 mg = 0.75 g |
| Grams (g) | Milligrams (mg) | Multiply by 1,000 | 1.2 g = 1,200 mg |
| Grams (g) | Kilograms (kg) | Divide by 1,000 | 4,500 g = 4.5 kg |
| Nanograms (ng) | Micrograms (mcg) | Divide by 1,000 | 200 ng = 0.2 mcg |
Write micrograms in full. The abbreviation mcg is acceptable; the Greek symbol is not, because handwritten it reads as mg and the resulting error is a thousandfold. Most safety guidance has said so for two decades and the symbol still appears, so it is worth being the person who does not use it.
Volume and Capacity
| From | To | Do this | Example |
|---|---|---|---|
| Millilitres (mL) | Litres (L) | Divide by 1,000 | 250 mL = 0.25 L |
| Litres (L) | Millilitres (mL) | Multiply by 1,000 | 1.5 L = 1,500 mL |
| Cubic centimetres (cc) | Millilitres (mL) | They are equal | 10 cc = 10 mL |
| Fluid ounces (fl oz) | Millilitres (mL) | Multiply by 30 | 8 fl oz = 240 mL |
| Teaspoons (tsp) | Millilitres (mL) | Multiply by 5 | 2 tsp = 10 mL |
| Tablespoons (tbsp) | Millilitres (mL) | Multiply by 15 | 1 tbsp = 15 mL |
| Cups | Millilitres (mL) | Multiply by 240 | 1.5 cups = 360 mL |
The fluid ounce figure is rounded. A US fluid ounce is 29.57 mL, and 30 is the number used on fluid balance charts because the difference across a day of oral intake is smaller than the error in estimating what a patient actually drank. Do not carry the rounding into a drug calculation.
Body Weight: The 2.2 That Goes the Wrong Way
Weight-based dosing fails more often on the direction of this conversion than on the arithmetic. The kilogram number is always smaller than the pound number.
| From | To | Do this | Example |
|---|---|---|---|
| Pounds (lb) | Kilograms (kg) | Divide by 2.2 | 154 lb = 70 kg |
| Kilograms (kg) | Pounds (lb) | Multiply by 2.2 | 60 kg = 132 lb |
| Stone | Kilograms (kg) | Multiply by 6.35 | 11 stone = 70 kg |
| Ounces (oz) | Grams (g) | Multiply by 28.35 | 6 oz = 170 g |
| Grams (g) | Kilograms (kg) | Divide by 1,000 | 3,200 g = 3.2 kg |
Neonatal weights are the place to be most careful, because they are often recorded in pounds and ounces by a parent and in grams by the unit. Convert the ounces separately and add them to the pounds before going anywhere near kilograms, rather than treating "7 lb 4 oz" as 7.4 lb.
Drip Factors: Printed, Not Derived
A drip factor is how many drops the giving set delivers per millilitre. It is a property of the set, printed on its packet, and it is not consistent between manufacturers. Nothing in a calculation tells you what it is — you have to read it.
| Set type | Drip factor | Typical use |
|---|---|---|
| Macrodrip | 10 drops/mL | Rapid fluid replacement, blood |
| Macrodrip | 15 drops/mL | General adult maintenance |
| Macrodrip | 20 drops/mL | General adult maintenance |
| Microdrip | 60 drops/mL | Paediatric, and any low or precise rate |
The gap between a 10 and a 60 set is a factor of six, and both are ordinary equipment. If a calculated drop rate looks implausible — more than about 100 drops a minute, or fewer than 5 — the drip factor is the first thing to re-read. The IV calculator takes the drip factor as an input for exactly this reason.
Rates and Time: Where 60 Comes In
| From | To | Do this | Example |
|---|---|---|---|
| mL/hour | mL/minute | Divide by 60 | 120 mL/h = 2 mL/min |
| mL/hour | Drops/minute | Multiply by drip factor, divide by 60 | 125 mL/h at 20 gtt/mL = 42 drops/min |
| Total volume and hours | mL/hour | Divide volume by hours | 1,000 mL over 8 h = 125 mL/h |
| mcg/kg/min | mg/hour | Multiply by weight and 60, divide by 1,000 | 5 mcg/kg/min at 70 kg = 21 mg/h |
The last row is two conversions stacked, and doing it in one step is a known source of error. Take the per-minute figure to a per-hour figure first, then deal with the units. An answer that is out by exactly 60 means the time conversion was applied once instead of twice, or not at all.
The Four That Cause Most of the Harm
Most of this chart is reference. Four rows in it account for a disproportionate share of real incidents, and they are worth knowing without looking.
| Conversion | Error size if wrong | What makes it fail |
|---|---|---|
| mcg to mg | 1,000x | Abbreviations that look alike in handwriting |
| Per-minute to per-hour | 60x | A two-step conversion done in one |
| Pounds to kilograms | 2.2x, either way | Multiplying where you should divide |
| Drip factor 10 vs 60 | 6x | Assuming the set instead of reading the packet |
Each of these is an error by a factor, not by a percentage, which is the one piece of good news. Nobody can judge whether 1,080 mg is right for a given patient, but almost anyone can see that 10,800 mg is not. Before checking the working, check whether the size of the answer is believable. More on how those failures arise in how dosing errors actually happen.
Using a Printed Chart Safely
A chart removes the recall step. It does not remove the checking step, and the two are easy to confuse once a laminated card is in your pocket.
- It can tell you that a milligram is a thousand micrograms. It cannot tell you that the order said milligrams and you read micrograms.
- Convert the units before you calculate the dose, not during. Mixing the two steps is where the factor errors hide.
- A second check is only independent if the other person works from the prescription, not from your answer.
- Where a conversion feeds a stock calculation, the dose stock calculator converts a required dose into the volume to draw up.
Questions About Nursing Conversions
How many micrograms are in a milligram?
One thousand. The same factor separates milligrams from grams, and grams from kilograms. Every step on the metric weight scale is a thousand, which is why a misread prefix is never a small error — it is always out by a factor of 1,000, and that size of mistake is visible if you look at the volume it produces.
Why is 1,000 mL called a litre on one chart and 1 kg on another?
Because water weighs one gram per millilitre, and most of what is infused is close enough to water for the equivalence to hold. A litre of saline is about a kilogram. This is useful for estimating a fluid balance, and it is not a licence to swap the units in a calculation — a drug concentration is per millilitre, never per gram.
Should I divide or multiply to convert pounds to kilograms?
Divide by 2.2. The direction catches people out because the numbers look similar at a glance and both operations produce a plausible answer. A useful check is that the kilogram figure is always the smaller of the two: a 154 lb patient is 70 kg, not 339. If your answer went up, you multiplied when you should have divided.
What is a drip factor and where do I find it?
It is the number of drops the giving set delivers per millilitre, and it is printed on the packet of the set itself. It is not derived from anything and it is not standard across sets. Macrodrip sets are commonly 10, 15 or 20 drops per mL; microdrip sets are 60. Using the wrong one changes the rate by up to six times.
How do I convert mL/hour to drops per minute?
Multiply the hourly volume by the drip factor and divide by 60. The 60 converts hours to minutes, and it is the step most often skipped. A rate of 125 mL/hour through a 20 drops/mL set is 125 x 20 / 60, which is about 42 drops per minute.
Are teaspoons and tablespoons safe to use for medicine at home?
Kitchen spoons are not, because they are not a measure. A teaspoon is defined as 5 mL and a tablespoon as 15 mL, but the spoons in a drawer vary by more than half. Where a dose is given in spoons, supply an oral syringe or a marked cup and convert the dose to millilitres first.
Why does a ratio strength like 1:1,000 appear on some ampoules?
It is an older way of writing concentration that survives on a few drugs, adrenaline being the common one. A 1:1,000 preparation is one gram in 1,000 mL, which is 1 mg/mL. A 1:10,000 preparation is 0.1 mg/mL. Convert the ratio to mg/mL before you calculate anything, because the two forms are not safely comparable by eye.
Does a conversion chart replace a second check?
No. A chart removes the recall step, not the verification step. It tells you that a milligram is a thousand micrograms; it cannot tell you that you read the order as micrograms when it said milligrams. The chart handles the arithmetic and a colleague working independently from the prescription handles the rest.
Medically Reviewed
Dr. Syeda Khadija Akbar
PharmD (Doctor of Pharmacy) — Medical Reviewer
The formulas, dosing logic, unit handling, and safety wording on this page were reviewed for clinical accuracy by Dr. Syeda Khadija Akbar, PharmD. This page is an educational reference only — always confirm any clinical calculation independently before acting on it.