Goal Weight Calculator
Enter your starting weight and goal weight. We'll show you how long it takes on each GLP-1 medication and the total cost to reach your goal - sorted from fastest to slowest.
Your goal
Your goal at a glance
Some drugs may not reach this goal - drugs cap out at their phase 3 peak (e.g. Wegovy caps at 14.9% loss). The table below shows which drugs can get you there.
How long & how much to reach 180 lbs
Sorted by fastest to slowest. Drugs marked "Unreachable" cap out below your goal.
How this projection works
The time-to-goal column applies each drug's phase 3 trial primary endpoint as an exponential approach to plateau. Wegovy's STEP-1 trial reported a 14.9% mean weight loss at 68 weeks, Zepbound's SURMOUNT-1 reported 22.5% at 72 weeks, Mounjaro's SURPASS/off-label reported around 20.9%, oral Wegovy's OASIS-4 reported 13.6%, and Foundayo (orforglipron)'s ATTAIN-1 reported 12.4%. We model the loss curve as weight_loss_pct(t) = peak × (1 - exp(-t / tau)), which closely matches published trial-week weight-loss data. Solving that equation for time gives the number of months each drug needs to hit your target loss percentage. Total cost = monthly channel price from your calculator multiplied by months to goal.
Three important limits. First, this projects the trial mean. Real-world outcomes typically land at 60-80% of the trial peak because of adherence gaps, slow dose escalation, and lifestyle-consistency variance - budget for that. Second, we do not model the mid-treatment plateau most patients hit around months 6-9. Third, if your goal requires losing more than a drug's trial peak percentage, the drug is flagged "Unreachable" rather than extrapolated past the endpoint data.
Why the fastest drug isn't always the cheapest path
The table sorts by time, but the interesting column for most cash-pay patients is total cost. Consider a 220 → 190 lb goal (13.6% loss). Zepbound at 22.5% peak in ~72 weeks reaches that target in about 8 months. Wegovy at 14.9% peak in ~68 weeks reaches it in about 14 months. Zepbound is almost twice as fast - but if you are cash-pay via LillyDirect vials ($299/mo for the 2.5 mg starter, stepping up) versus Wegovy NovoCare ($349/mo standard, dropping to $199 for the first two months of promotional pricing), the total spent to reach the goal can actually be lower on Wegovy despite the longer timeline. The cost column captures that flip.
The pattern reverses when insurance covers one drug and not the other. If your plan covers Wegovy at a $25 copay but denies Zepbound entirely, the covered-Wegovy path is almost always cheapest even though Zepbound reaches the goal faster. Change the "Payment channel" dropdown above to see which drug wins under each scenario.
Frequently asked questions
Is this a medical recommendation?
No. This calculator projects the mathematical time-and-cost path implied by each drug's phase 3 trial primary endpoint - it is not a treatment recommendation, does not know your medical history, and does not model dose escalation timing, side effects, drug interactions, or contraindications. Decisions about starting, switching, or stopping a GLP-1 belong with a licensed prescriber who knows your full clinical picture.
Why does the projection say a drug is "Unreachable" for my goal?
Every GLP-1 has a mathematical ceiling equal to its phase 3 trial peak - Wegovy caps at 14.9% (STEP-1), Zepbound at 22.5% (SURMOUNT-1), Saxenda at 8.4% (SCALE), and so on. If your goal weight requires losing more than a drug's peak percentage of your starting weight, the projection returns "Unreachable" rather than extrapolating past the trial-endpoint data. In practice, some patients exceed trial averages with dose optimization, adjunct strategies, or longer-than-trial timeframes - but for a math-only projection we do not extrapolate beyond what the primary endpoint supports.
What if I plateau before reaching my goal?
This calculator does not model plateaus explicitly - it applies the same trial-derived per-week percentage until the goal is reached. In the real world, most patients experience a slowdown around months 6-9 driven by adaptive metabolic and appetite changes. If you are already on a GLP-1 and plateauing, the practical options are dose escalation (if you are not on the maximum dose), longer time on the current dose, switching to a higher-efficacy molecule, or accepting the plateau as a new baseline. Plateau management is a conversation to have with your prescriber, not a math problem for this widget.
Does insurance status change the time-to-goal number?
No - the time projection depends on the drug and dose, not on how you paid for it. What insurance changes is the TOTAL COST column. A patient with commercial insurance and the Wegovy Savings Card may reach a 15% weight loss for a couple of hundred dollars over 15 months; a self-pay patient on the same drug at the NovoCare reference price may spend $5,000+ over the same period. Same time-to-goal, radically different total-cost math.
What BMI cutoffs matter for insurance coverage?
Most commercial insurers that cover weight-loss GLP-1s require BMI ≥30, or BMI ≥27 with a weight-related comorbidity (hypertension, dyslipidemia, sleep apnea, prediabetes). If your calculated goal weight would drop you below BMI 27, some plans will discontinue coverage mid-treatment. That is a separate policy question from clinical outcomes - talk to your prescriber and check your plan's policy language before assuming coverage will continue at lower weights.
Why did my friend lose more weight than the trial average?
Phase 3 trial results are population averages with wide individual variance. STEP-1 reported a ~14.9% mean weight loss for Wegovy at 68 weeks, but the distribution runs from patients who lost under 5% to patients who lost over 25%. The mean is the honest expectation for a projection but is not a guarantee - some patients over-perform, others under-perform, and both outcomes are represented in the same trial data. This calculator projects the mean; your actual outcome depends on adherence, dose escalation, individual response, and lifestyle factors the widget cannot model.