How do I reconstitute a peptide vial?

Use bacteriostatic water — typically 1-3 mL depending on your target dose and how many doses you want per vial. Draw the BAC water with an 18-gauge reconstitution needle, then slowly inject it into the peptide vial down the side wall (do not squirt directly onto the lyophilized powder). Swirl until the powder dissolves fully (shaking won't damage the peptide). Let it dissolve completely (30-60 seconds) before drawing your first dose with an insulin syringe.

How many units on an insulin syringe equals one mg?

It depends on how you reconstituted the vial. If you have a 5mg vial reconstituted with 1 mL of BAC water, then 1 mg = 20 units on a standard 100-unit (1 mL) insulin syringe. If you used 2 mL, then 1 mg = 10 units. Our dose calculator handles this math for you — enter vial mg, mL of water, and target dose, and it returns the exact units.

How long does a reconstituted peptide vial stay good?

28 days at refrigerator temperature (2-8°C / 36-46°F) is the typical beyond-use date (BUD) for peptides reconstituted with bacteriostatic water (0.9% benzyl alcohol preservative). Mark the reconstitution date on the vial. Do not freeze a reconstituted vial — the freeze-thaw cycle can degrade the peptide.

What syringe should I use to inject peptides?

A 29-gauge or 30-gauge insulin syringe, 1 mL (100-unit) capacity, with a fixed needle (½ inch or 5/16 inch length). Use a separate 18-gauge needle ONLY for drawing the bacteriostatic water during reconstitution — never inject with the 18g.

Where do I inject peptides?

Most research peptides are administered subcutaneously into the abdomen (1-2 inches from the navel), thigh, or upper outer arm. Rotate injection sites to avoid lipohypertrophy (tissue thickening at repeated injection sites). Pinch the skin slightly, insert the needle at 45-90° depending on subcutaneous fat depth, push the plunger slowly, then withdraw and apply gentle pressure with an alcohol wipe.

Is the dosing calculator free?

Yes — completely free, no account required, no email signup. Works on any device. We built it because most peptide buyers do the math wrong the first time and either under-dose (no effect) or over-dose (waste a vial and risk side effects). Bookmark the page or save the protocol card we generate.

Dosing calculator — goodtides

Pick a peptide

We'll tell you exactly how much bacteriostatic water to mix with and how many units to draw for each common dose.

Pick a peptide above.

Once you do, we'll show you the exact mL of bacteriostatic water to add and the unit count for each common dose. No calculator math required.

Supplies you'll need

1× lyophilized peptide vial (the powder one — the dose calculator above tells you the size)
1× bacteriostatic (BAC) water vial
1× 18-gauge reconstitution needle (the bigger one — for mixing only)
1× 1mL insulin syringe with 29-gauge needle (the smaller one — for dosing)
2× alcohol prep wipes
1× sharps container for disposal

What is BAC water?

Bacteriostatic water is sterile water with 0.9% benzyl alcohol added — the alcohol keeps bacteria out of your vial for 28 days at refrigeration after you puncture it. NOT the same as tap water. NOT the same as plain sterile water. Use ONLY BAC water.

Vacuum check (this is a quality signal)

Peptide vials (the powdered ones) ship under vacuum. The BAC water vial does not. Here's the flow:

1. Draw the EXACT amount of BAC water you need into your recon syringe from the BAC water vial.

2. Insert the BAC-water-filled syringe into the peptide vial's rubber stopper.

3. The peptide vial's vacuum will suck the BAC water out of the syringe IN AUTOMATICALLY — you should not have to push the plunger.

✓ Strong auto-pull = peptide vial seal is intact. Proceed.

✗ No suction / you have to push it in = vacuum was broken before delivery. Possible contamination — do NOT use. Photo + email hello@goodtides.shop for replacement.

Because the vacuum pulls in ALL the BAC water in your syringe, draw the EXACT target volume BEFORE piercing the peptide vial. If you draw 4mL when you needed 3mL, the vacuum takes all 4mL and your peptide will be over-diluted.

Swirl gently. Never shake.

Tilt the syringe so the BAC water runs DOWN THE SIDE WALL of the vial — never directly onto the powder cake. Fluid force from direct injection can shear delicate peptide molecules. Once mixed, rotate the vial slowly in your hand for ~15 seconds. Shaking creates foam and damages the peptide.

How to inject (subcutaneous)

Switch to the SMALL 1mL insulin syringe (29-gauge). Wipe the rubber stopper with alcohol again. Draw to the unit-line shown above (e.g. 15 units).

Pick a site: abdomen (avoid 2-inch radius around belly button), outer thigh, or upper arm. Pinch a fold of skin. Insert needle at a 45-degree angle (subcutaneous = under skin, not into muscle). Inject slowly. Withdraw. Discard the needle in your sharps container — never reuse.

Common mistakes

Using tap water or plain sterile water — neither is preserved. Use ONLY BAC water.
Shaking the vial — gentle swirl only.
Reusing needles — single-use, every dose. They cost $0.15.
Skipping the alcohol wipe — the preservative protects contents, not the stopper.
Drawing the wrong volume of BAC water before piercing — vacuum will pull all of it in.
Storing peptides in the freezer — refrigerate only (2–8°C), never freeze.

Reconstitute

Mix with 2 mL of bacteriostatic water

For a clean, stable solution that lines up with the doses below.

Draw your dose

Then on a 1 mL insulin syringe, draw:

Tap any dose to see it filled on the syringe below.

Custom peptide amount, water, or dose

Peptide in the vial

Milligrams of peptide powder in the vial — from the label, not the bottle's mL size.

BAC water added

Override what we recommended in step 01 above.

Target dose

A custom amount per injection.

Syringe size

Most people use 1mL / 100-unit insulin syringes (29-31G).

How this is calculated

Concentration = vial mg ÷ BAC water mL = mg per mL.

Volume needed = target dose ÷ concentration, then converted to syringe units (1 mL = 100 units on a standard insulin syringe).

Always verify against the COA's specific guidance and your physician's prescription. This is a math tool, not medical advice.

Dosing recommendations are general guidance based on commonly cited protocols — not medical advice or a prescription. Peptide therapy at goodtides requires a valid physician evaluation. Talk to your physician before starting, adjusting, or combining any peptide protocol, especially if you have underlying conditions or take other medications.

Exactly how many units.

Mix with 2 mL of bacteriostatic water

Then on a 1 mL insulin syringe, draw:

Take your dose:

2–8°C, protected from light.

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