Give the planner a goal weight and a pace and it returns a date, a daily calorie gap and a sanity check on whether the target makes sense for your height.
Weight Loss Planner
Set a goal weight and a pace, and see the date, the deficit and whether the target is sensible.
Method: about 7,700 kcal per kilogram (3,500 per pound) of fat. That rule is a decent guide over weeks and increasingly optimistic over months, because energy needs fall as bodyweight does. The planner will not build a timeline to a goal below a BMI of 18.5.
Estimates only — general education, not medical advice. Talk with your doctor before changing how you eat or train. More tools at whatshouldiweigh.com.
How the maths works, and where it breaks
A pound of body fat stores roughly 3,500 calories, so a 500-calorie daily deficit should produce about a pound a week. That's the rule behind every projection you'll see, including this one.
It's a decent guide over weeks and increasingly optimistic over months.
The problem is that it treats your metabolism as fixed. It isn't. As you lose weight three things happen at once:
You get smaller. A lighter body costs less to maintain and less to move. Dropping 20 pounds might reduce your daily maintenance by 100–150 calories on its own — so the deficit you set at the start has partly closed itself.
You move less without deciding to. Non-exercise activity falls during sustained restriction. You sit sooner, fidget less, take the lift.
Resting metabolism dips slightly beyond what the tissue loss predicts.
Net effect: real weight loss curves flatten. The linear projection this planner gives you is a best case, and treating a slowdown at month three as failure is the most common reason people quit something that was working.
The fix is to recalculate every 10–15 pounds rather than running one figure to the end.
Choosing a pace
The planner offers four, and slower is usually better than it feels.
| Pace | Daily deficit | Suits |
|---|---|---|
| 0.5 lb / week | ~250 kcal | Already lean, or protecting performance |
| 1 lb / week | ~500 kcal | Most people, most situations |
| 1.5 lb / week | ~750 kcal | Higher starting bodyweight |
| 2 lb / week | ~1,000 kcal | Higher bodyweight, short term only |
The useful guideline is no more than about 1% of your bodyweight per week. For a 200-pound person that's two pounds; for a 140-pound person it's under one and a half. Beyond that, the share of loss coming from muscle rises sharply, and so does the chance of abandoning the whole thing.
Faster is not better. Losing 30 pounds in three months and regaining 25 is worse than losing 30 in six months and keeping it.
Why the planner won't chart every goal
If your goal weight would put you below a BMI of 18.5, the planner declines to build a timeline and suggests talking to a doctor or dietitian instead.
That isn't a technical limitation. Below the healthy range, the costs are real — reduced bone density, disrupted hormonal function in both sexes, impaired immune response, loss of muscle including cardiac muscle. Those aren't trade-offs an online calculator is equipped to help anyone weigh.
If your target sits below that line, the conversation worth having is with a professional who can look at the whole picture.
What makes the difference over months
The planner gives you a number. Keeping to it is the actual work, and a few things move the needle more than pace selection does.
Protein high, resistance training regular. This is what determines whether you lose fat or lose weight. Same deficit, very different outcome.
Weekly averages, not daily readings. Bodyweight swings two to four pounds a day on food volume, sodium, hydration and glycogen. Weigh daily if you like, but judge only the weekly average — otherwise you're reading noise and reacting to it.
Expect flat weeks. Fat loss is not linear even when adherence is perfect. Two or three weeks of no movement followed by a sudden drop is normal, particularly for women across the menstrual cycle.
Add movement before cutting further. When progress stalls, more steps generally beats fewer calories. It doesn't compound the metabolic adaptation, and it's easier to sustain.
Common questions
How long to lose 20 pounds? At one pound a week, about 20 weeks. Expect longer in practice — the last stretch runs slower as your maintenance falls.
Is 2 pounds a week safe? For someone at a higher starting weight, short term, yes. For someone already close to a healthy weight it's too aggressive and will cost muscle.
Why have I stopped losing? Usually maintenance has fallen with your bodyweight, or intake has crept up without being noticed. Recalculate your target and check your logging honestly for a week before assuming something is wrong.
Should I do cardio or lift? Lift, and add walking. Resistance training protects the muscle you want to keep; walking adds burn without spiking appetite the way hard cardio can.
Does the scale weight matter most? No. Body composition matters more, and the tape often shows progress when the scale doesn't — particularly early on, when people are gaining muscle and losing fat at similar rates.
The calculators on this site are educational estimates, not medical advice. Talk with your doctor or a registered dietitian before starting a weight-loss plan, particularly if you have a medical condition or take medication affecting appetite or blood sugar. If food or your weight is occupying more of your thoughts than you'd like, that's worth raising with someone too.