You've got your peptide powder. You've mixed it with bacteriostatic water. Now you're staring at a syringe.

How much do you inject?

The vial says 5mg. Your protocol says 250mcg. The syringe measures in units. Nothing matches up.

You need to convert mg to mcg. Calculate concentration. Figure out injection volume. One mistake and you're either underdosing (wasting money) or overdosing (risking side effects).

Let me show you the exact math. No confusion, no guessing, no mistakes.

Why dosage calculation matters

Peptide dosing isn't like taking a pill. You're dealing with:

• Powder measured in milligrams (mg)

• Water measured in milliliters (ml)

• Doses measured in micrograms (mcg)

• Syringes marked in units (IU)

Get any calculation wrong and your entire protocol is off.

Too little peptide:

• Waste money on ineffective dosing

• Won't see results

• Frustration and quitting

Too much peptide:

• Increased side effects

• Wasted peptide (more isn't better)

• Safety concerns

• Depleting vials too quickly

Accurate dosing ensures you get results safely and efficiently.

Understanding the units

First, let's clarify what each measurement means.

Milligrams (mg)

This is how peptide powder is measured. Your vial label shows mg.

Common vial sizes:

• 2mg vials

• 5mg vials (most common)

• 10mg vials

The powder inside is 2mg, 5mg, or 10mg of actual peptide.

Micrograms (mcg or μg)

This is how doses are measured. Your protocol will specify mcg.

Critical conversion: 1mg = 1,000mcg

So:

• 5mg vial = 5,000mcg total

• 2mg vial = 2,000mcg total

• 10mg vial = 10,000mcg total

Milliliters (ml)

This is how bacteriostatic water is measured.

Common amounts added:

• 1ml

• 2ml (most common)

• 3ml

Units (IU)

This is how insulin syringes are marked.

Critical conversion: 100 units = 1ml

So:

• 10 units = 0.1ml

• 20 units = 0.2ml

• 50 units = 0.5ml

The concentration formula

When you add water to peptide powder, you create a concentration.

Formula: Concentration (mcg/ml) = Total peptide (mcg) ÷ Water added (ml)

Example 1:

• Vial: 5mg (5,000mcg)

• Water: 2ml

• Concentration: 5,000mcg ÷ 2ml = 2,500mcg/ml

Example 2:

• Vial: 5mg (5,000mcg)

• Water: 1ml

• Concentration: 5,000mcg ÷ 1ml = 5,000mcg/ml

Example 3:

• Vial: 2mg (2,000mcg)

• Water: 2ml

• Concentration: 2,000mcg ÷ 2ml = 1,000mcg/ml

The concentration tells you how many micrograms of peptide are in each milliliter of solution.

The dose volume formula

Once you know concentration, calculate how much to inject.

Formula: Injection volume (ml) = Dose needed (mcg) ÷ Concentration (mcg/ml)

Example 1: BPC-157

• Need: 250mcg

• Concentration: 2,500mcg/ml

• Volume: 250 ÷ 2,500 = 0.1ml (10 units)

Example 2: TB-500

• Need: 2,500mcg (2.5mg)

• Concentration: 2,500mcg/ml

• Volume: 2,500 ÷ 2,500 = 1ml (100 units)

Example 3: Ipamorelin

• Need: 200mcg

• Concentration: 2,500mcg/ml

• Volume: 200 ÷ 2,500 = 0.08ml (8 units)

This tells you exactly how much liquid to draw from your vial for each injection.

Converting ml to syringe units

Insulin syringes measure in units, not ml. You need to convert.

The conversion:

• 1ml = 100 units

• 0.1ml = 10 units

• 0.01ml = 1 unit

Quick reference chart:

To convert: ml × 100 = units

Examples:

• 0.12ml × 100 = 12 units

• 0.33ml × 100 = 33 units

• 0.75ml × 100 = 75 units

Step-by-step calculation process

Let's work through a complete example from start to finish.

Scenario: You have a 5mg vial of BPC-157. Your protocol calls for 250mcg twice daily.

You're adding 2ml of bacteriostatic water.

Step 1: Convert vial size to mcg 5mg × 1,000 = 5,000mcg total peptide

Step 2: Calculate concentration 5,000mcg ÷ 2ml = 2,500mcg/ml

Step 3: Calculate injection volume 250mcg ÷ 2,500mcg/ml = 0.1ml per dose

Step 4: Convert to syringe units 0.1ml × 100 = 10 units on insulin syringe

Step 5: Calculate doses per vial 5,000mcg total ÷ 250mcg per dose = 20 doses

Step 6: Calculate vial duration 20 doses ÷ 2 daily = 10 days per vial

Answer: Inject 0.1ml (10 units) twice daily. Each vial lasts 10 days.

Our peptide dosage calculator does all these steps automatically - just enter your vial size, water amount, and desired dose.

Common peptide dosage examples

Let's calculate doses for the most popular peptides.

BPC-157 dosage calculation

Standard protocol: 250mcg twice daily

Setup:

• Vial: 5mg (5,000mcg)

• Water: 2ml

• Concentration: 2,500mcg/ml

Calculation:

• 250mcg ÷ 2,500mcg/ml = 0.1ml

• 0.1ml = 10 units

Result: Inject 10 units twice daily

For detailed BPC-157 protocols based on injury type, see our complete BPC-157 guide.

TB-500 dosage calculation

Loading phase: 5mg twice weekly

Setup:

• Vial: 5mg (5,000mcg)

• Water: 2ml

• Concentration: 2,500mcg/ml

Calculation:

• 5,000mcg ÷ 2,500mcg/ml = 2ml

• 2ml = 200 units (entire vial)

Result: Use entire vial per injection (2ml split across two syringes if using 1ml syringes)

For complete TB-500 protocols, read our TB-500 guide.

Semaglutide dosage calculation

Starting dose: 0.25mg (250mcg) weekly

Setup:

• Vial: 5mg (5,000mcg)

• Water: 2ml

• Concentration: 2,500mcg/ml

Calculation:

• 250mcg ÷ 2,500mcg/ml = 0.1ml

• 0.1ml = 10 units

Result: Inject 10 units once weekly

Titration doses:

• 0.5mg = 0.2ml (20 units)

• 1mg = 0.4ml (40 units)

• 1.7mg = 0.68ml (68 units)

• 2.4mg = 0.96ml (96 units)

Use our semaglutide dosage calculator for complete titration schedules. For comparison with tirzepatide, read semaglutide vs tirzepatide.

Ipamorelin dosage calculation

Standard protocol: 200mcg 2-3x daily

Setup:

• Vial: 5mg (5,000mcg)

• Water: 2ml

• Concentration: 2,500mcg/ml

Calculation:

• 200mcg ÷ 2,500mcg/ml = 0.08ml

• 0.08ml = 8 units

Result: Inject 8 units 2-3 times daily

For complete muscle-building protocols with Ipamorelin, see best peptides for muscle growth.

HGH Fragment 176-191 calculation

Fat loss protocol: 250mcg daily fasted

Setup:

• Vial: 5mg (5,000mcg)

• Water: 2ml

• Concentration: 2,500mcg/ml

Calculation:

• 250mcg ÷ 2,500mcg/ml = 0.1ml

• 0.1ml = 10 units

Result: Inject 10 units each morning before fasted cardio

Use our HGH fragment calculator for body weight-adjusted protocols.

Adjusting for different water amounts

You can use different amounts of water. This changes concentration but not total peptide.

5mg vial with different water amounts:

More water (2-3ml):

• Easier to measure small doses

• Larger injection volumes

• More injections per vial

Less water (1ml):

• Higher concentration

• Smaller injection volumes

• Fewer injections per vial

Neither is better - choose based on your comfort with injection volumes.

For complete reconstitution instructions, read how to reconstitute peptides.

Calculating doses per vial

Know how long your vial lasts before you run out.

Formula: Doses per vial = Total peptide (mcg) ÷ Dose per injection (mcg)

Example 1: BPC-157 twice daily

• Total: 5,000mcg

• Dose: 250mcg × 2 daily = 500mcg/day

• Days per vial: 5,000 ÷ 500 = 10 days

Example 2: Ipamorelin 3x daily

• Total: 5,000mcg

• Dose: 200mcg × 3 daily = 600mcg/day

• Days per vial: 5,000 ÷ 600 = 8.3 days

Example 3: Semaglutide weekly

• Total: 5,000mcg

• Dose: 1,000mcg (1mg) weekly

• Weeks per vial: 5,000 ÷ 1,000 = 5 weeks

Calculating vials needed for protocols

Plan ahead so you don't run out mid-cycle.

Formula: Vials needed = (Total days × Daily dose) ÷ Vial size

Example 1: BPC-157 8-week protocol

• Protocol: 250mcg twice daily for 56 days

• Daily dose: 500mcg

• Total needed: 56 × 500 = 28,000mcg (28mg)

• Vials: 28mg ÷ 5mg = 5.6 vials

• Order: 6 vials

Example 2: TB-500 12-week protocol

• Loading: 5mg twice weekly × 4 weeks = 40mg

• Maintenance: 2.5mg weekly × 8 weeks = 20mg

• Total: 60mg

• Vials: 60mg ÷ 5mg = 12 vials

• Order: 12 vials

Example 3: Ipamorelin + CJC stack

• Ipamorelin: 200mcg 3x daily × 84 days = 50.4mg (11 vials)

• CJC-1295: 200mcg 2x weekly × 12 weeks = 4.8mg (1 vial)

• Total order: 11 Ipamorelin + 1 CJC vials

Use our peptide cost calculator to calculate exact vial quantities and total costs for any protocol.

Weight-based dosing calculations

Some peptides dose by body weight (mcg/kg).

Formula: Dose (mcg) = Body weight (kg) × mcg per kg

Example: BPC-157 at 4mcg/kg

Person weighs 180 lbs:

• Convert to kg: 180 ÷ 2.20462 = 81.6kg

• Calculate dose: 81.6kg × 4mcg/kg = 326mcg

• Round to: 325mcg per injection

Then calculate injection volume:

• Concentration: 2,500mcg/ml

• Volume: 325mcg ÷ 2,500 = 0.13ml (13 units)

Common weight-based peptides:

• BPC-157: 2.5-4 mcg/kg

• TB-500: 30-60 mcg/kg (loading dose)

• Growth hormone peptides: 2-3 mcg/kg

Our BPC-157 dosage calculator and TB-500 dosage calculator automatically adjust for body weight.

Common calculation mistakes

Let's address what people get wrong.

Mistake 1: Forgetting to convert mg to mcg

Wrong: 5mg vial ÷ 2ml = 2.5mg/ml 250mg dose needed 250 ÷ 2.5 = 100ml to inject (impossible!)

Right: 5mg = 5,000mcg 5,000mcg ÷ 2ml = 2,500mcg/ml 250mcg ÷ 2,500 = 0.1ml (10 units)

Always convert mg to mcg by multiplying by 1,000.

Mistake 2: Using wrong peptide amount

Wrong: Assuming all vials are 5mg when you have 2mg or 10mg

Right: Check your vial label every time Calculate based on actual vial size Label reconstituted vials with concentration

Mistake 3: Mixing up units and ml

Wrong: "I need 0.2ml so I'll draw to the 20 mark" (If using 1ml syringe marked to 100 units)

Right: 0.2ml = 20 units on a 100-unit syringe Always convert: ml × 100 = units

Mistake 4: Not tracking doses remaining

Wrong: Injecting until vial is empty, unsure if you're getting full doses

Right: Calculate total doses when you reconstitute Mark vial with date and track injections Discard after 28 days even if liquid remains

Mistake 5: Rounding incorrectly

Wrong: 0.083ml = "about 10 units I guess"

Right: 0.083ml × 100 = 8.3 units Round to 8 units (slightly underdosed) or 9 units (slightly overdosed) Be consistent with your rounding

Troubleshooting dosing issues

Problems happen. Here's how to fix them.

Problem: Can't draw exact calculated amount

Example: Calculator says 8.3 units but syringe only has 1-unit marks

Solution:

• Round to nearest unit (8 or 9)

• Be consistent - always round the same way

• Small variations (1-2 units) won't affect results

Problem: Dose requires more than one syringe

Example: TB-500 dose is 2ml but you have 1ml syringes

Solution:

• Use two syringes, draw 1ml in each

• Inject both (two injection sites)

• Or get 2ml-3ml syringes for larger volumes

Problem: Not sure if calculation is correct

Solution:

• Double-check each step

• Use our peptide reconstitution calculator to verify

• Start with lower dose if uncertain (can always increase)

• Better to slightly underdose than overdose

Problem: Vial concentration unknown

Example: Forgot to label reconstituted vial

Solution:

• If uncertain, discard and start fresh

• Never guess at concentration

• Always label immediately after reconstitution

• Write: peptide name, concentration, date mixed

Using calculators vs manual math

You can calculate manually or use our tools. Both work.

Manual calculation benefits:

• Understand the math

• Can calculate anywhere

• No internet needed

Calculator benefits:

• Eliminates math errors

• Faster for complex protocols

• Shows IU and ml automatically

• Calculates costs and vial quantities

Recommended approach:

• Learn the math (read this guide)

• Use calculators for daily dosing (faster, more accurate)

• Double-check with manual math if result seems wrong

Our free calculators:

• Peptide dosage calculator - all peptides

• Peptide reconstitution calculator - concentration and volumes

• BPC-157 calculator - injury-specific protocols

• TB-500 calculator - loading and maintenance

• Semaglutide calculator - complete titration

• HGH Fragment calculator - fat loss protocols

• Stack calculator - multiple peptides

• Cost calculator - budget planning

Quick reference formulas

Save these for quick calculations.

Basic conversions:

• 1mg = 1,000mcg

• 1ml = 100 units

• Weight (kg) = Weight (lbs) ÷ 2.20462

Core formulas:

• Concentration = Total mcg ÷ ml of water

• Injection volume (ml) = Dose (mcg) ÷ Concentration (mcg/ml)

• Injection volume (units) = Injection volume (ml) × 100

• Doses per vial = Total mcg ÷ Dose per injection (mcg)

Standard concentrations (5mg vial):

• With 1ml water: 5,000mcg/ml

• With 2ml water: 2,500mcg/ml

• With 3ml water: 1,667mcg/ml

The bottom line

Peptide dosing math is straightforward once you understand the units.

The key steps:

1. Convert vial mg to mcg (multiply by 1,000)

2. Calculate concentration (mcg ÷ ml of water)

3. Calculate injection volume (dose ÷ concentration)

4. Convert ml to units (multiply by 100)

Master these calculations and you'll dose accurately every time.

Or use our free calculators and skip the math entirely. Both approaches work.

The important thing: accurate dosing means better results, fewer side effects, and optimized peptide use.

Calculate right. Dose right. Get results.

Related guides

• How to reconstitute peptides - Complete mixing guide before calculating doses

• BPC-157 vs TB-500 - Compare dosing protocols for both peptides

• Best peptides for injury recovery - Specific dosing by injury type

• Best peptides for weight loss - Calculate doses for GLP-1 and fat loss peptides

• Best peptides for muscle growth - Dosing for growth hormone peptides

In case I don’t see you, good afternoon, good evening, and good night. Cheers.