Gaining weight on purpose sounds simple — eat more — until you try to do it well. Most people either gain too fast and add mostly fat, or eat big for a week, see the scale barely move, and give up. A plan turns “eat more” into numbers you can actually follow.

The Feedee Weight Gain Calculator builds that plan from three numbers: your current weight, your target weight, and your weekly pace. From those it works out your total gain, how many weeks the journey takes, the daily calorie surplus you need, and your projected goal date.

What Does the Feedee Weight Gain Calculator Do?

This calculator turns a weight goal into a weekly schedule. You enter your current weight in pounds, the weight you want to reach, and your chosen pace in pounds per week. It returns your total gain, the weeks required, the daily calorie surplus, the total surplus calories, and your projected goal date.

The engine is the classic energy-balance rule: roughly 3,500 extra calories build one pound. Multiply your weekly pace by 500 to get the daily surplus, since 3,500 divided by 7 is 500. One pound per week therefore needs about 500 extra calories a day.

How to Use the Feedee Weight Gain Calculator

Start with your current weight. Weigh yourself first thing in the morning for the most consistent number. Day-to-day swings of a pound or two are normal, so use a recent average rather than your lightest-ever reading.

Next enter your target weight — higher than your current weight. Pick a target tied to something real: a weight class, a doctor’s recommendation, or the size where your strength felt right.

Finally choose your weekly gain goal, between 0.25 and 3 pounds per week. Half a pound weekly is gentle, one pound is the classic moderate pace, and anything above two is aggressive and best kept short. Press Calculate and read your timeline.

The 3,500-Calorie Rule Explained

The 3,500-calorie figure comes from the energy stored in a pound of body tissue. Eat 3,500 calories beyond what your body burns, and the surplus gets stored — mostly as fat, partly as muscle if you are training. The calculator uses this rule because it is simple, well-tested, and close enough for planning.

It is still an approximation. Treat the calculator’s surplus as your starting prescription, then adjust after two or three weeks based on what the scale actually does.

Choosing a Sensible Weekly Pace

Pace is the most important decision in the whole plan. Gain too fast and a larger share of each pound is fat; gain too slowly and motivation fades before the goal date. For most healthy adults, 0.5 to 1 pound per week is the sweet spot where a good share of the gain can be muscle — provided you train with resistance and eat enough protein.

Faster paces have their place. Someone rebuilding after being underweight might aim for 1.5 to 2 pounds weekly for a limited stretch. Above 2 pounds a week, fat gain dominates and eating gets uncomfortable. The calculator allows up to 3, but treat the aggressive end as a short-term tool.

Why Your Starting Weight Matters

Two people with the same 20-pound goal can need very different plans. A 130-pound person gaining to 150 adds about 15% of their body weight; a 200-pound person gaining to 220 adds 10%. The lighter person’s surplus is a bigger relative change to their eating, which is why hard gainers often feel like they are force-feeding.

Your starting weight also sets your maintenance calories. The calculator gives you the surplus above maintenance, not total intake. If your maintenance is 2,400 and your pace needs 500 extra, your real target is about 2,900 a day. You will need to know or estimate your maintenance separately.

Worked Example: Gaining 20 Pounds at One Pound Per Week

First: note the inputs. Current weight 140 lb, target weight 160 lb, pace 1 lb per week.

Then: find the total gain. 160 minus 140 equals 20 lb.

Then: divide by the pace. 20 lb divided by 1 lb per week equals 20 weeks.

Then: compute the daily surplus. 1 lb per week times 500 equals 500 kcal per day.

Answer: about 20 weeks, 500 extra calories daily, roughly 70,000 surplus calories in total. A steady, classic muscle-building pace.

Worked Example: A Gentle Half-Pound Weekly Pace

First: note the inputs. Current weight 155 lb, target weight 165 lb, pace 0.5 lb per week.

Then: total gain is 165 minus 155, which equals 10 lb.

Then: weeks needed are 10 divided by 0.5, which equals 20 weeks.

Then: daily surplus is 0.5 times 500, which equals 250 kcal per day.

Answer: 20 weeks at just 250 extra calories a day — about one large snack. This is the “lean gain” approach lifters use to keep fat gain minimal.

Worked Example: A Short Aggressive Push

First: note the inputs. Current weight 175 lb, target weight 187 lb, pace 2 lb per week.

Then: total gain is 187 minus 175, which equals 12 lb.

Then: weeks needed are 12 divided by 2, which equals 6 weeks.

Then: daily surplus is 2 times 500, which equals 1,000 kcal per day.

Answer: 6 weeks at a 1,000-calorie daily surplus. Effective for a short burst, but expect more of the gain to be fat, and do not stay at this pace longer than planned.

What Counts Toward Your Surplus

A surplus is food beyond maintenance, and protein decides what the gain becomes. Aim for roughly 0.7 to 1 gram of protein per pound of body weight daily if you want muscle in the mix. Without training stimulus and protein, extra calories default to fat storage.

Liquid calories are the hard gainer’s best friend: milk, smoothies, and shakes add hundreds of calories without the fullness of solid food. Calorie-dense staples — nuts, peanut butter, olive oil, rice, oats — raise intake without heroic portions. Track for at least two weeks; most people who “eat tons” discover they eat big one day and tiny the next.

The Difference Between Scale Weight and Real Gain

The scale lies in the short term. When you raise calories, especially carbohydrates, your muscles store extra glycogen and each gram of glycogen holds about 3 grams of water. The first week of a gaining plan can show a 2- to 4-pound jump that is mostly water — encouraging, but not tissue.

Judge the plan on weekly averages, not daily readings. Weigh daily if you like, but compare this week’s average to last week’s. If the trend matches your chosen pace within a quarter pound, the plan is working.

Plateaus: When the Math Stops Working

A plan that worked for six weeks often stalls in week seven. As you get heavier, maintenance calories rise: the 500-calorie surplus that moved the scale at 140 lb may be only a 300-calorie surplus at 150 lb, because a bigger body burns more.

The fix is a small bump, not an overhaul. Add 150 to 250 calories a day, wait two weeks, and reassess. Re-enter your new current weight in the calculator and it rebuilds the timeline from where you actually are.

Common Weight Gain Mistakes

The classic mistake is dirty bulking — treating the surplus as permission to eat anything. You will gain weight, but body composition and energy suffer, and the cut afterward is miserable. A surplus built on mostly whole foods beats a junk-food free-for-all every time.

Two more errors are common. First, skipping the tracking: “eating more” without numbers drifts back to maintenance within days. Second, gaining fast with no training: without resistance exercise, fast weight gain is overwhelmingly fat. Surplus plus stimulus plus protein is the complete formula.

Where Weight Gain Planning Is Useful

Athletes use gain plans to move up a weight class with control instead of panic-eating. People rebuilding after illness or appetite loss use them to recover safely with a doctor’s guidance. Hard gainers — light eaters with fast metabolisms — use them because intuition alone never reached the goal.

Coaches of young athletes benefit too, since a written plan with a goal date beats vague advice to “eat more.” In every case the value is the same: the goal stops being a wish and becomes a schedule with a daily calorie number attached.

How to Interpret Your Result Correctly

Read the headline first: the weeks and the goal date. That date assumes you hit your surplus nearly every day — consistency matters more than perfection, but a plan followed four days a week is not the plan the calculator priced.

The daily surplus is the number to memorize; it is your actual job each day. The projected date is a finish line to aim at, not a promise. Re-run the calculator monthly with your fresh weight and it stays honest as your body changes.

Frequently Asked Questions

1. How many extra calories do I need to gain one pound per week?

About 500 per day above maintenance. One pound of body weight stores roughly 3,500 kcal, and spreading that over 7 days gives 500 a day. The calculator uses exactly this math: daily surplus = weekly pace × 500.

2. Is gaining 2 pounds per week too fast?

For most people, yes, as an ongoing pace. Above about 1 lb per week, a growing share of the gain is fat rather than muscle. Paces of 1.5–2 lb weekly suit short, deliberate pushes — such as recovering lost weight — not months-long plans.

3. Why am I not gaining weight even though I eat a lot?

Almost always, the surplus is smaller or less consistent than it feels. Big meals followed by tiny ones average out near maintenance. Track everything for two weeks; the numbers usually reveal the gap, and then the calculator tells you the daily target to hit.

4. Do I need to exercise to gain weight?

Not to gain weight — a surplus alone adds pounds. But without resistance training, most of the gain is fat. If you want the gain to include muscle, lift weights 3–4 times weekly and eat enough protein alongside your surplus.

5. How much protein should I eat while gaining?

Roughly 0.7–1 gram per pound of body weight daily. A 150 lb person aims for about 105–150 g. Protein does not replace the surplus — you need both — but it directs the gain toward muscle instead of fat.

6. What if my target weight is lower than my current weight?

The calculator will ask for a higher target, since it plans gains only. For fat loss you need a deficit plan instead — the same 3,500-calorie rule in reverse, usually at 0.5–1 lb per week.

7. Can I gain weight without counting calories?

Some people can, by adding consistent calorie-dense habits: a daily shake, bigger portions, an extra meal. But counting — at least for the first few weeks — is how you learn what your surplus actually looks like. Most successful gainers track until the habits are automatic.

8. Why did I gain 4 pounds in the first week?

Mostly water and glycogen, not tissue. Extra carbs refill muscle glycogen, and each gram binds about 3 grams of water, plus extra food volume in your gut. Do not celebrate or panic — judge the plan on multi-week trends.

9. Should I keep gaining if I feel too full all the time?

Constant discomfort is a signal to adjust, not quit. Switch some solid food for calorie-dense liquids, spread intake over more meals, and consider dropping the pace to 0.5 lb per week. A plan you cannot eat is not a plan.

10. Does the goal date account for missed days?

No — it assumes you hit your surplus consistently. Missed days push the real date later. When life interrupts, re-run the calculator with your current weight and it will rebuild an honest timeline from where you are.

11. Is it normal for weight gain to slow down over time?

Yes. A heavier body burns more calories, so a fixed surplus shrinks in effect as you grow. When the scale stalls for 2–3 weeks, add 150–250 calories a day and reassess after another two weeks.

12. What foods are best for a clean calorie surplus?

Nuts, nut butters, olive oil, whole milk, eggs, rice, oats, potatoes, and fatty fish give the most calories per bite with solid nutrition. Shakes and smoothies add calories without much fullness.

13. How often should I weigh myself?

Daily weighing with weekly averaging works best. Step on each morning under the same conditions, then compare weekly averages. Single readings swing with water, salt, and meal timing; averages reveal the true trend.

14. Can teenagers use this calculator?

The math works, but growing teens have moving targets — growth spurts change maintenance constantly. Teens should involve a parent and, ideally, a doctor or dietitian rather than chasing a number alone.

15. When should I stop gaining?

When you hit the target you set for a real reason — a weight class, a health recommendation, a performance goal — or when further gain is clearly adding fat, not function.