GLP-1 Cost Per Pound Lost Calculator

How the math works

Every brand-name GLP-1 obesity drug has a published mean weight loss percentage from its FDA pivotal trial. We use the FDA-label values:

• Wegovy 2.4 mg (semaglutide) — 14.9% mean weight loss over 68 weeks in STEP-1 [5].
• Zepbound 5 mg (tirzepatide) — 15.0% over 72 weeks in SURMOUNT-1 [2].
• Zepbound 10 mg (tirzepatide) — 19.5% over 72 weeks in SURMOUNT-1 [2].
• Zepbound 15 mg (tirzepatide) — 20.9% over 72 weeks in SURMOUNT-1 [2][6].
• Foundayo 17.2 mg (orforglipron) — 11.1% over 72 weeks per the FDA-approved Foundayo prescribing information (the labeled maximum dose) [3].
• Saxenda 3 mg (liraglutide) — 8.0% over 56 weeks in SCALE [4].

For time horizons shorter than the trial endpoint, the calculator scales linearly along an S-curve anchored to the published intra-trial milestones: month 1 = 25%, month 3 = 55%, month 6 = 80%, month 9 = 95%, month 12+ = 100% of the trial-endpoint loss. Most weight loss occurs in months 1-9 then plateaus, so this is a rough but reasonable approximation. Then: lbs lost = starting weight × (trial % × time factor) and $/lb = (monthly cost × months) ÷ lbs lost.

Reference table — $/lb lost at common weights (12 months, list price)

The table below assumes you stay on therapy for 12 months and pay the typical US brand cash list price (Wegovy and Saxenda at $1,349/mo, Zepbound at $1,086/mo, Foundayo at $999/mo). Plug your real out-of-pocket cost into the calculator above for an accurate personal number.

Pattern to notice: dollar-per-pound is essentially independent of starting weight at a fixed percentage — which is exactly why efficacy percentage matters more than starting weight when comparing drugs. A 150 lb patient and a 300 lb patient will see similar $/lb on the same drug; the heavier patient just sees a bigger absolute pound number.

Frequently asked questions

Why does cost per pound matter more than monthly cost?

Two drugs with the same monthly price can produce very different total weight loss. A $1,000/month drug that helps you lose 50 lbs is dramatically more efficient than an $800/month drug that helps you lose 20 lbs. Cost per pound lost normalizes for efficacy so you compare what you actually get for the spend.

Which GLP-1 has the lowest cost per pound lost?

At list price, Zepbound 15 mg (tirzepatide) is the most efficient brand-name option because its 20.9% trial weight loss is the highest of any FDA-approved obesity drug, and Lilly's monthly list price is similar to Wegovy. Compounded semaglutide and tirzepatide can be even cheaper per pound — see our cheapest compounded semaglutide guide — but compounding carries quality and supply risk.

Are these numbers accurate for me personally?

They are an honest projection based on trial averages, not a guarantee. Roughly half of trial participants lost more than the mean and half lost less. Adherence, dose escalation, diet, sleep, and biology all matter. Treat the calculator as a planning tool, not a prediction.

Why is tirzepatide cheaper per pound despite a similar monthly cost?

Because SURMOUNT-1 [6] showed tirzepatide 15 mg produced 20.9% mean weight loss versus 14.9% for semaglutide 2.4 mg in STEP-1 [5]. More pounds lost for the same monthly spend means a lower dollar-per-pound number, even when the sticker prices are close. This is the head-to-head efficacy gap covered in detail in our tirzepatide vs semaglutide head-to-head.

What about compounded versions?

Compounded semaglutide and tirzepatide can drop the monthly cost to $150 to $300, which collapses the cost per pound lost. The math changes dramatically. See our cheapest compounded semaglutide guide for current pricing and the supply and quality caveats you need to understand first.

Does insurance change the math?

Yes, dramatically. If your plan covers Wegovy or Zepbound at a $25 to $50 copay, the cost per pound drops by an order of magnitude. Plug your actual out-of-pocket monthly cost into the calculator above instead of the brand list price to see your real number. For coverage strategy, see our GLP-1 pricing index.

Important disclaimer

This tool is for educational purposes only and does not constitute medical advice. The projected weight loss values come from the published mean efficacy data in the FDA prescribing information for each drug and from the underlying NEJM trial publications. Individual results vary substantially. Pricing assumptions are list prices and will not match your real out-of-pocket cost. Weight Loss Rankings does not provide medical advice, diagnosis, or treatment recommendations.

Related tools and research

• Tirzepatide vs semaglutide head-to-head — why the SURMOUNT-1 efficacy edge drives the $/lb gap
• Foundayo vs Wegovy vs Zepbound comparison — the three-way GLP-1 obesity drug comparison
• GLP-1 pricing index — current cash and insurance prices across the brands
• Cheapest compounded semaglutide — how compounding changes the $/lb math
• GLP-1 weight loss calculator — week-by-week trial-curve weight loss predictor
• GLP-1 savings calculator — how much you save vs cash brand pricing