How to Use a Peptide Calculator: Inputs, Formula, and Example

A peptide calculator is a unit-conversion tool. It can make concentration and draw volume arithmetic easier to check, but it cannot determine whether the values are correct for a person or situation.

PeptideCalc does not identify a medication or choose a vial amount, diluent, water volume, dose, syringe, or schedule. Use only values you have independently confirmed. The software is for informational and educational use, not medical advice, diagnosis, or treatment.

What the calculator does with your entries

The browser calculator converts your desired amount to milligrams when necessary, then uses three pieces of arithmetic:

On the browser tool, the 0.3 mL/30-unit, 0.5 mL/50-unit, and 1.0 mL/100-unit selections each represent 0.01 mL per marked unit. The selected scale changes the visual capacity of the marker, not the concentration formula.

Enter the four fields in the browser calculator

Open the Syringe tab for this walkthrough. The separate Nasal spray tab uses a different set of inputs. The browser tool handles one vial amount at a time; it does not identify a compound or choose values from its name.

On a fresh visit, the numeric fields are blank and the 100-unit/1 mL option is selected. Check that scale against the actual syringe you are using. Reset clears your entries and restores mcg and the 100-unit/1 mL scale. Example values appear only when you select Load example.

1. Step 1: Enter Vial content in mg

   Copy the total vial amount in milligrams into Vial content. This is the amount in the whole vial, not the amount for one calculation. Use a shortcut or type a custom number.

2. Step 2: Enter Liquid added in mL

   Enter the liquid volume in milliliters in Liquid added. The tool uses this as the volume for its concentration calculation. It does not choose a diluent or a liquid volume for you.

3. Step 3: Enter Desired amount and check its unit

   Enter an independently determined amount, then check whether the field shows mcg or mg. Switching the unit converts the existing number: 250 mcg becomes 0.25 mg, with the same calculated volume.

4. Step 4: Match the U-100 syringe capacity

   Choose 30 units/0.3 mL, 50 units/0.5 mL, or 100 units/1 mL to match the U-100 scale you are checking. These options change capacity; they do not change the concentration or the amount represented by one U-100 unit.

5. Step 5: Read and independently verify the result

   Read Calculated marking for units and mL, then check all three lines under The math. Compare the result with the marking chart and the markings on the actual syringe. A software result is not a medical recommendation.

Check the example: 5 mg, 2 mL, and 250 mcg

Select Load example to reproduce these entries in the current browser calculator. They demonstrate the arithmetic and are not suggested values for personal use.

• Vial content: 5 mg
• Liquid added: 2 mL
• Desired amount: 250 mcg, which equals 0.25 mg
• Syringe capacity: 100 units/1 mL

1. Find concentration: 5 mg ÷ 2 mL = 2.5 mg/mL.
2. Find volume: 0.25 mg ÷ 2.5 mg/mL = 0.1 mL.
3. Find the U-100 marking: 0.1 mL × 100 units per mL = 10 units.

A useful manual check is dimensional: milligrams divided by milligrams per milliliter leaves milliliters. Then milliliters divided by milliliters per marked unit leaves syringe units.

Read mg, mcg, mL, and units as different quantities

Milligrams (mg) and micrograms (mcg) describe mass. Milliliters (mL) describe volume. In this tool, a U-100 unit is 0.01 mL, so 10 units is 0.1 mL. It is not a fixed mass: the example concentration makes 10 units equal 250 mcg, but a different concentration changes that amount.

To convert mcg to mg, divide by 1,000. To convert mg to mcg, multiply by 1,000. The calculator's mg and mcg buttons convert the existing entry for you. If 250 mcg is already entered, select mg and the field becomes 0.25. Typing 250 after that switch would describe a different amount. These metric relationships follow the NIST SI prefix definitions. The interface writes micrograms as mcg.

Use the chart and plunger without losing track of your inputs

The Marking chart shows units, mL, and mass at the concentration you entered. Find the row labeled calculated marking to compare it with the result above. The chart changes when your inputs change.

Dragging the illustrated plunger, or using the arrow keys when its control has focus, changes Desired amount. It leaves Vial content and Liquid added alone. For example, moving the loaded example from 10 to 11 units changes the result to 0.11 mL and the desired amount to 275 mcg. Use Load example to restore the starting entries.

This vial reports whole draws of your entered amount and any arithmetic remainder. The example shows 20 full draws because 5 mg divided by 0.25 mg is 20. This count does not account for liquid left in the vial or needle.

Important checks before relying on the display

• Confirm that mg and mcg were not reversed; 1 mg equals 1,000 mcg.
• Confirm that the vial label and liquid volume were copied exactly.
• Confirm that the selected syringe capacity and markings match the actual device.
• Recalculate concentration and draw volume independently.
• If the result exceeds capacity, the tool keeps the full calculated number and warns that it is past the scale. It does not shorten the result to make it fit. Verify the entries, units, equipment, and plan before proceeding.
• If a result is fractional or below one unit, do not round it to the nearest illustrated tick. The drawing is a reference; actual printed tick spacing varies.

The fields accept decimal numbers within the tool's supported ranges and show an error for unsupported entries. A valid number only means the interface can process it; it does not establish that the value is medically appropriate.

Browser calculator versus iOS app workflow

The browser calculator is free and designed for a calculation in the current page. The separate PeptideCalc app for iPhone and iPad was listed at $4.99 on the U.S. App Store when checked on October 27, 2026. It adds saved protocols, schedules, reminders, dose logs, offline use, and optional iCloud sync for supported app data.

In the iOS workflow, the user still supplies the medication and calculation values, chooses the schedule, and configures reminders. The app stores, displays, and acts on those choices; it does not prescribe or generate a treatment plan.

The iPhone and iPad app can also run the calculation in reverse. If you already have independently confirmed vial content and a target dose, read the automatic Water Amount guide to see how Syringe Units mode solves for a liquid volume from a chosen syringe mark.

Privacy: what is and is not sent

Values entered into the website calculator are processed in the browser and are not sent to analytics. The website does use self-hosted, cookieless aggregate analytics for visits and fixed interaction events. The iOS app uses limited analytics and crash diagnostics, stores most app data locally by default, and can use optional Apple services such as iCloud when enabled. Read the PeptideCalc privacy policy for the current details and controls.

Peptide calculator FAQ

To compare the browser tool with the separate iPhone and iPad app, read our best peptide reconstitution calculator guide, including its publisher-bias disclosure.