The world’s best peptide dosage calculator
No email. No signup. No paywall. Just the dosage, across 30+ research compounds.
Featured this month.
The two compounds we’re getting the most calculator queries for. Both available as 3 ml / 300-click pens — no vial mixing, no syringe drawing.
Retatrutide
3ml pen · 10 / 20 / 30 / 40mg · 300 clicks
The most-searched GLP-1 of 2026. Triple-receptor agonist (GLP-1 + GIP + glucagon) — the strongest fat-loss data in the GLP-1 class so far. Pen format means click-counting, not vial drawing.
Open the Retatrutide calculator →KLOW Stack
3ml pen · 80mg blend · 300 clicks
Pre-mixed BPC-157 + TB-500 + GHK-Cu + KPV in a single pen. The complete healing-plus-skin-plus-immune stack without the faff of mixing four separate vials. Most popular blend at our partner.
Open the KLOW calculator →What are you researching?
Pick the category that matches your research focus. Each category has a dedicated landing page + multiple compound pages, each with the calculator embedded.
🩹 Healing
Tissue repair and recovery research.
BPC-157, TB-500, IGF-1 LR3, LL-37, Thymosin Alpha 1.
💪 Growth
GH secretagogue research.
Ipamorelin + CJC-1295, MOTS-c, HGH, Tesamorelin, AOD 9604.
🧠 Cognitive
Brain-active peptides and nootropics.
Selank, Semax, Adrafinil, Lion’s Mane.
😴 Sleep
Sleep-architecture research compounds.
DSIP.
🍽️ Metabolic
GLP-1 research compounds (UK prescription-only — info only).
Retatrutide, Semaglutide, Tirzepatide, Cagrilintide.
🧴 Skin
Skin, hair and ECM research compounds.
GHK-Cu, Melanotan II.
❤️ Specialty
Longevity, libido and hormonal research.
NAD+, FOXO4-DRI, PT-141, Kisspeptin, Oxytocin.
🔗 Stacks
Pre-mixed research stacks.
Wolverine (BPC + TB-500), GLOW (+ GHK-Cu), KLOW (+ KPV).
Four calculations. One tool.
Mix your vial
Work out exactly how much bacteriostatic water to add to your vial, and the concentration you end up with.
Dose accurately
Enter your target dose. Get back the exact volume to draw, the syringe-unit mark to draw to, and a visual breakdown of the maths.
Stack compounds
Calculate per-compound doses for named blends like the Wolverine, GLOW, and KLOW stacks — or build your own.
Plan a protocol
Build a week-by-week cycle for any compound or stack. Drag in dose × frequency, see the pharmacokinetic concentration plot live, get a shareable URL — no sign-up.
Why Stackcalc?
The peptide and nootropic dose calculator built by researchers, for researchers.
Free forever
No signup, no paywall, no upsell to a paid version. The maths stays free, full stop.
Pen-format aware
Handles the 3 ml / 300-click pens properly — Retatrutide, GLOW, KLOW, Wolverine. Most calculators get pen maths wrong.
Independent
We don’t sell peptides, so the maths is honest. No incentive to fudge dosages to move stock.
What this is, and what it isn’t.
Stackcalc is a free peptide calculator. It does the reconstitution and dosage maths you’d otherwise be doing in your head with a syringe in one hand and a vial in the other.
We do not sell peptides or nootropics. We do not recommend doses. We do not provide medical advice. Every calculation on this site is for research and educational purposes — the volumes and concentrations we return are the mathematical results of the numbers you enter, nothing more.
We do, however, point you in the right direction. Each compound page has a “Where to source” section linking to our trusted UK supplier — independently verified, UK-based, and operating under the same research-only framing as this site.
🇬🇧 Built in the UK. Designed and operated in Glasgow.
🔬 Research-grade language. Every compound page uses research-only framing.
🔒 No tracking of inputs. Calculator inputs stay in your browser.
Compliance: Stackcalc.co.uk provides calculator tools and information for research and educational purposes only. We do not sell, supply, or recommend peptides, nootropics, or any other compounds. Content on this site does not constitute medical advice. Compounds discussed are not licensed as medicines for human use unless explicitly stated. Several compounds are prescription-only medicines in the United Kingdom — refer to each compound page for specific regulatory status. Always consult a qualified healthcare professional. Not for human consumption.