How to Calculate IGF-1 LR3 Dosage (+ Calculator)

Every IGF-1 LR3 dose calculation reduces to one equation. Your concentration is the vial amount in mcg divided by the water you add in mL. Your injection volume is your target dose in mcg divided by that concentration.

Concentration (mcg/mL) = total mcg in vial ÷ mL of bacteriostatic water added

Injection volume (mL) = target dose (mcg) ÷ concentration (mcg/mL)

The only conversion to memorize is that 1 mg equals 1000 mcg. A 1 mg vial holds 1000 mcg of peptide. The third number you need is how a U-100 insulin syringe reads, because that is what you actually measure with.

Reconstitution sets your concentration before you ever calculate a dose. Use bacteriostatic water, not sterile water, because the benzyl alcohol preservative lets a reconstituted vial last in the refrigerator for weeks rather than one use. See bacteriostatic water vs sterile water for why the preservative matters.

This table shows the concentration produced by common 1 mg vial and water combinations, plus the syringe units for a reference 40 mcg dose.

Aim the water stream down the inside wall of the vial, not directly onto the powder, then swirl gently until clear. Do not shake. For step-by-step reconstitution technique, see how to reconstitute peptides. Reconstituted IGF-1 LR3 holds potency in the refrigerator for roughly 2 to 4 weeks; details in how long reconstituted peptides last.

Common research-context protocols run 20 to 120 mcg per day, with cycle lengths held to 4 to 6 weeks because of receptor downregulation concerns. IGF-1 LR3 carries an extended biological half-life of roughly 20 to 30 hours, compared with about 12 to 15 hours for native IGF-1, because the Arg3 substitution and N-terminal extension cut its binding to IGF binding proteins by over 100-fold and keep it circulating in the active free form (Buckway et al., 2001, Journal of Clinical Endocrinology & Metabolism). That long half-life is why daily single doses are typical rather than multiple injections.

Start at the low end and hold it for at least the first week. IGF-1 is the primary mediator of growth hormone's anabolic signal, driving skeletal muscle protein synthesis through the PI3K/Akt/mTOR pathway and stimulating satellite cell proliferation (Florini et al.; Velloso, 2008, British Journal of Pharmacology), so higher doses do not linearly produce better outcomes and raise hypoglycemia risk.

Cycle length matters as much as daily dose. Most research-context protocols cap a run at 4 to 6 weeks rather than running continuously, on the reasoning that sustained IGF-1 receptor stimulation can blunt receptor sensitivity over time. A common pattern is 4 weeks on followed by an equal or longer break before any subsequent cycle. Track your starting dose, daily units, and cycle dates so you can reproduce or adjust the protocol on a later run instead of guessing. For how IGF-1 LR3 fits a broader training stack, see peptides for bodybuilding, and for outcome expectations see IGF-1 LR3 results.

Two injection strategies exist, and they change where you place the needle, not the calculation. Systemic dosing puts the full daily dose into a single subcutaneous site, usually the abdomen, to raise circulating IGF-1 LR3 throughout the body. Localized dosing splits the dose into the specific muscles trained that day, based on the unproven theory that local concentration favors growth in those fibers.

For localized work, divide the daily dose across target muscles. A 40 mcg daily dose split bilaterally across biceps becomes 20 mcg (2 units) per arm. Localized injection is intramuscular into the worked muscle belly rather than subcutaneous.

The evidence for site-specific hypertrophy from localized IGF-1 LR3 in humans is anecdotal. Systemic IGF-1 still reaches local muscle and activates satellite cells through the IGF-1 receptor (Velloso, 2008, British Journal of Pharmacology). Whichever route you choose, review sterile injection technique in how to inject peptides.

The most common timing places the dose immediately after training, within 15 to 30 minutes of finishing. The rationale is that exercise increases blood flow and IGF-1 receptor sensitivity in the worked tissue, so a post-workout injection meets a primed receptor environment.

On rest days, users running systemic protocols typically dose at a fixed morning or pre-meal time to keep daily exposure consistent. Because the half-life spans 20 to 30 hours, a single daily injection maintains steady levels without splitting the dose across the day.

For bilateral muscles trained the same session, split the localized dose evenly left and right. A 30 mcg post-workout dose for a leg day becomes 15 mcg (1.5 units at 1000 mcg/mL) into each quad. Keep injection sites rotated to avoid local tissue irritation.

Most IGF-1 LR3 dosing errors are measurement errors, not protocol errors. A single misread of the syringe can deliver ten times the intended dose.

Confusing units with mcg. A syringe "unit" is a volume mark, not a microgram. At 1000 mcg/mL, 1 unit equals 10 mcg, but at 500 mcg/mL, 1 unit equals 5 mcg. Always recompute units against your actual concentration after every reconstitution.

Ignoring the syringe scale. A U-40 insulin syringe is not a U-100. On a U-40 syringe, 40 units equals 1 mL, so the same volume reads at a different number. Verify your syringe is U-100 before applying any unit figure in this guide.

Decimal-point overdoses. Reading 0.30 mL as 30 units instead of 0.03 mL as 3 units is a tenfold error. Because IGF-1 LR3 lowers blood glucose, a tenfold overdose carries real hypoglycemia risk: shakiness, sweating, confusion, and in severe cases loss of consciousness. Keep fast-acting carbohydrate on hand.

Reusing stale math. When you change vial size or water volume, your entire unit table changes. Recalculate from scratch. A 1 mg vial in 1 mL gives 10 mcg per unit, but the same vial in 2 mL gives 5 mcg per unit, so an old 3-unit habit silently halves or doubles your dose.

Skipping the syringe-volume check. Some insulin syringes hold only 0.3 mL (30 units) or 0.5 mL (50 units) total. If your calculated dose exceeds the barrel capacity, you cannot draw it in one pull. Confirm the barrel size covers your largest planned dose before you reconstitute. General precautions are covered in the peptide safety guide.