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Peptide Calculator: Reconstitution and unit converter for mg, mcg and mL
The short answer
To get a peptide solution’s concentration, divide the total mass by the final volume of the solution: 10 mg in 5 mL is 10,000 mcg ÷ 5 mL = 2,000 mcg/mL (2 mg/mL). To find the volume that holds an amount, divide the amount by that concentration: 250 mcg ÷ 2,000 mcg/mL = 0.125 mL. This calculator does both directions, converts mg ⇄ mcg exactly and shows every step.
Arithmetic only, not medical advice. The numbers above are an arithmetic example, not a dose. Follow your prescriber’s or pharmacist’s instructions.
Milligrams ⇄ micrograms
1 mg = 1,000 mcg. The decimal point moves three places, so this conversion is exact.
Privacy What you type stays in this browser tab. The calculator uses no account, storage, cookies, analytics or network requests.
01 Formulas
How the peptide calculator maths works
Reconstitution maths only needs two facts about a solution: how much mass it contains and its final volume. Everything else follows from four relationships, and the calculator applies them in this order.
Milligrams to micrograms
mcg = mg × 1,000 mg = mcg ÷ 1,000
The metric prefix milli means one thousandth and micro means one millionth, so 1 mg is exactly 1,000 mcg. The calculator moves the decimal point three places on the digits you type, so the result is exact with no rounding.
Concentration
concentration (mcg/mL) = total mass (mcg) ÷ final solution volume (mL) concentration (mg/mL) = concentration (mcg/mL) ÷ 1,000
Use the final volume of the finished solution, as stated on your label or by your pharmacist. The calculator measures; it does not tell you how much liquid to add.
Volume that holds an amount
volume (mL) = amount (mcg) ÷ concentration (mcg/mL)
Convert the amount and the concentration to the same mass unit first. The calculator does this for you and refuses an amount larger than the total mass in the solution.
Amount in a volume
amount (mcg) = volume (mL) × concentration (mcg/mL)
This is the same relationship read the other way. A volume larger than the final solution volume is rejected.
Unit definitions: NIST: Metric (SI) prefixes; NIST: SI units of volume.
02 Worked examples
Worked examples
Each example uses hypothetical round numbers chosen to show the arithmetic. They are not doses and not a suggestion. The steps are generated by the same code that runs the calculator.
Arithmetic example A
Concentration from total mass and final volume
A solution contains 10 mg in a final volume of 5 mL. What is its concentration?
- 10 mg × 1,000 = 10,000 mcg total
- 10,000 mcg ÷ 5 mL = 2,000 mcg/mL
- 2,000 mcg/mL ÷ 1,000 = 2 mg/mL
The solution is 2,000 mcg/mL, which is the same as 2 mg/mL.
Arithmetic example B
The volume that holds a given amount
In that same 2,000 mcg/mL solution, how much volume holds 250 mcg?
- 10 mg × 1,000 = 10,000 mcg total
- 10,000 mcg ÷ 5 mL = 2,000 mcg/mL
- 2,000 mcg/mL ÷ 1,000 = 2 mg/mL
- 250 mcg ÷ 2,000 mcg/mL = 0.125 mL
250 mcg is in 0.125 mL of this solution.
Arithmetic example C
The amount in a given volume, in mixed units
A different solution holds 3 mg in a final volume of 2 mL. How much is in 0.4 mL?
- 3 mg × 1,000 = 3,000 mcg total
- 3,000 mcg ÷ 2 mL = 1,500 mcg/mL
- 1,500 mcg/mL ÷ 1,000 = 1.5 mg/mL
- 0.4 mL × 1,500 mcg/mL = 600 mcg (0.6 mg)
0.4 mL of this solution holds 600 mcg, which is 0.6 mg.
03 Unit glossary
mg, mcg, mL and why there’s no IU field
- mg (milligram)
- A unit of mass equal to one thousandth of a gram. 1 mg = 1,000 mcg.
- mcg or µg (microgram)
- A unit of mass equal to one millionth of a gram. “mcg” and “µg” mean the same thing; “mcg” is harder to misread as “mg” in handwriting.
- mL (millilitre)
- A unit of volume equal to one thousandth of a litre. One cubic centimetre (cc or cm³) is exactly 1 mL.
- mg/mL and mcg/mL
- Concentration: how much mass is in each millilitre of a solution. 1 mg/mL = 1,000 mcg/mL.
- Reconstitution
- Turning a dry powder back into a liquid solution. For the arithmetic, all that matters is the total mass and the final volume of the solution.
- IU and “units”
- International units (IU) measure biological activity and are defined separately for each substance, so there is no universal IU-to-mg factor. The “units” marked on some measuring devices are a volume scale that differs between devices. This calculator works in mg, mcg and mL only and does not convert IU or units. If your instructions use either, ask your pharmacist or prescriber.
04 Unit errors
Common unit errors to check for
Most wrong answers in unit maths come from a handful of slips. They are worth checking every time, whatever tool you use.
Mixing up mg and mcg
A milligram is 1,000 times a microgram. Reading one as the other gives an answer that is wrong by a factor of 1,000. Check the unit toggle beside every mass field.
Mixing up mg/mL and mcg/mL
The same solution can be written as 2 mg/mL or 2,000 mcg/mL. Comparing a number in one unit with a number in the other is a 1,000-fold slip.
A misplaced decimal point
0.5 and 5 differ tenfold, and so do 0.05 and 0.5. Write a leading zero (0.5, not .5) and avoid trailing zeros (5, not 5.0) so a decimal point can't be missed.
Using the wrong volume
Concentration uses the final volume of the finished solution. If your label or pharmacist states it, use that number.
Treating mL, mg and “units” as interchangeable
They measure different things: volume, mass and, depending on context, activity or a device scale. The FDA has reported dosing errors in which confusion between milliliters, milligrams and “units” may have contributed.
Source: FDA (July 2024): dosing errors linked to confusion between mL, mg and “units”.
05 FAQ
Peptide calculator FAQ
How do I calculate peptide reconstitution?
Divide the total mass in the solution by its final volume to get the concentration. For example, 10 mg in a final volume of 5 mL is 10,000 mcg ÷ 5 mL = 2,000 mcg/mL (2 mg/mL). To find the volume that holds an amount, divide the amount by the concentration. The calculator does both steps and shows the working.
How many mcg are in 1 mg?
1 mg is exactly 1,000 mcg. To convert mg to mcg, multiply by 1,000; to convert mcg to mg, divide by 1,000.
How do I convert mg/mL to mcg/mL?
Multiply by 1,000. A concentration of 2 mg/mL is 2,000 mcg/mL, and 0.5 mg/mL is 500 mcg/mL.
Is this a peptide dosage calculator? Will it tell me my dose?
It does the dosage arithmetic only: converting between mg, mcg and mL within a solution you describe. It does not suggest an amount, a protocol or how to prepare, measure or administer anything, and it is not medical advice. Follow your prescriber’s or pharmacist’s instructions and ask them to check any calculation involving a medicine.
Why doesn’t the calculator convert IU or device “units”?
International units measure biological activity and are defined separately for each substance, and the unit markings on measuring devices differ between devices. Neither converts to mg or mL with one universal factor, so the calculator sticks to mg, mcg and mL.
Does the calculator save or send what I type?
No. Values stay in your browser tab’s memory while the page is open. The calculator uses no account, storage, cookies, analytics or network requests, and clearing or closing the page removes them.
Is there a peptide calculator app?
Yes. PepMod for iPhone and Android includes a unit and reconstitution converter alongside protocol tracking, dose logs, reminders and progress charts.
What should I do if a result looks wrong?
Check each unit toggle (mg or mcg), the position of every decimal point, and that you entered the final solution volume. Open Show the math to see each step. If the numbers still don’t match your instructions, ask your pharmacist or prescriber before using them.
Sources
PepMod app
Keep the whole protocol in one place.
PepMod has this unit converter built in, next to protocol tracking, dose logs, reminders and progress charts. For iPhone and Android.