Comparing compounds by price per milligram feels like the obvious move. It's the unit the whole market prices in. But for tirzepatide and retatrutide, that comparison points you the wrong way entirely. You've probably assumed retatrutide carries a steep price premium. Current vendor data says otherwise.
This isn't just trivia. If price has been the thing holding you back from retatrutide, you need to be doing this math on a weekly dose basis, not a per-milligram basis. The picture shifts considerably once you do.
How the dosing actually works
Both compounds use the same slow titration approach: start low, increase incrementally over weeks to months, let your body adjust as you go. Where they differ is the ceiling.
Tirzepatide follows the protocol from its own clinical trials, the SURMOUNT and SURPASS series. It starts at 2.5 mg per week and climbs by 2.5 mg every four weeks as tolerated, with a studied maximum of 15 mg per week. In practice, most research protocols land somewhere between 5 and 10 mg weekly for maintenance, which means a single maintenance week runs through 7.5 to 10 mg of compound.
Retatrutide was studied at meaningfully lower doses. Phase 2 trial starting doses were 0.5 to 1 mg per week, titrating up to 2, 4, and 8 mg over several months. The highest dose arm hit 12 mg weekly, but the 4 and 8 mg groups already showed substantial weight loss with an easier side effect profile. For context, the 8 mg group in the main Phase 2 trial showed mean weight loss exceeding 17% at 24 weeks and around 24% at 48 weeks. A weekly maintenance dose of 4 to 8 mg captures most of what the research actually documented.
Here's the upshot. A week of tirzepatide at maintenance doses runs through roughly two to three times more milligrams than a week of retatrutide at comparable research doses.
The weekly cost, side by side
Using current median vendor pricing across tracked research suppliers, here's what a week of each compound actually costs at typical maintenance doses.
| Compound | Weekly Dose | At Median Price | Monthly (approx.) |
|---|---|---|---|
| Tirzepatide | 5 mg/week | $48/week | ~$192 |
| Tirzepatide | 10 mg/week | $96/week | ~$385 |
| Retatrutide | 4 mg/week | $40/week | ~$161 |
| Retatrutide | 8 mg/week | $81/week | ~$323 |
Median price per mg is pulled from our live vendor tracking ($9.62/mg tirzepatide across 4 vendors; $10.09/mg retatrutide across 5 vendors) and updates automatically as prices change. Compare current prices in the pricing tool.
The per-milligram prices in our live tracking are nearly identical for both compounds. The weekly cost gap you see in the table above comes almost entirely from the dosing difference, not from any real price premium on retatrutide. At lower maintenance doses, retatrutide comes out comparable to, or actually cheaper than, tirzepatide per week.
Vendor pricing still swings substantially at the low end for both compounds. Check current vendor ranges in the pricing tool before you commit to a source.
Why retatrutide gets away with lower doses
The dose difference isn't arbitrary and it isn't a marketing trick. It reflects a real difference in potency and mechanism.
Tirzepatide works through two receptors, GLP-1 and GIP, both contributing to appetite suppression and better insulin response. It needs to be present in a large enough quantity to meaningfully drive both pathways, which is why doses climb into the 5 to 15 mg range.
Retatrutide works through three, GLP-1, GIP, and glucagon. That glucagon piece adds a metabolic dimension the dual agonists simply don't have. It increases energy expenditure, not just appetite suppression. That third pathway appears to amplify the whole effect, which is part of why the compound produces outsized weight loss at relatively modest doses. You're not just eating less, your metabolic rate is being pushed in a way tirzepatide doesn't directly touch.
If you're in perimenopause or postmenopause, that metabolic piece is worth understanding on its own. Metabolic rate tends to slow with the hormonal shifts of midlife, and that's a direct physiological effect, not a verdict on your caloric intake or exercise habits. A compound that addresses energy expenditure alongside appetite speaks to that picture in a way a GLP-1-only or dual agonist doesn't. That doesn't make it the right choice for everyone, but it's why researchers and clinicians are paying close attention to the triple agonist approach for this exact population.
What you're actually paying for
Since weekly costs at current market prices land in a similar range, the real question isn't "can I afford retatrutide." It's "what does retatrutide offer that tirzepatide doesn't."
Here's what the trial data shows so far. Tirzepatide produced average weight loss around 20 to 22% of body weight in its Phase 3 trials. Retatrutide's Phase 2 data showed 24% or more at 48 weeks. Those trials weren't run under identical conditions, so a direct comparison only goes so far, but the directional signal, that retatrutide may outperform tirzepatide on total weight outcomes, has held up across everything published so far.
What isn't settled yet: the full side effect profile, the long-term safety picture, and how retatrutide performs in larger, more diverse Phase 3 populations. Tirzepatide has years of post-approval real-world data behind it. Retatrutide doesn't, not yet. That's not a reason to write it off, but it is a real difference in how much confidence the evidence can currently support.
At current market prices, retatrutide doesn't carry a meaningful cost premium over tirzepatide in the research market. The per-milligram number that scared a lot of researchers away simply doesn't hold up anymore. The real decision points are mechanism, evidence quality, and regulatory status, not a price gap that puts one compound out of reach.
A note on approval status
Tirzepatide is FDA-approved as Mounjaro (type 2 diabetes) and Zepbound (obesity), so a prescription path actually exists. Retatrutide is still in Phase 3 trials as of mid-2026 with no FDA approval. Both show up in research markets, but the regulatory picture is genuinely different, and that affects how each one can realistically be accessed and used.
For the full research notes on each compound, including mechanism detail, trial citations, and current vendor pricing, see the Tirzepatide research note and the Retatrutide research note. To compare current prices across vendors, use the Peptide Price Lab pricing tool.
Citations for the clinical trial data referenced here are listed in the Tirzepatide and Retatrutide research notes. To compare current prices across vendors, see the Vendor Directory. For more on GLP-1 compounds and weight research, see the Weight Research and Metabolic Health tag pages.