A weight cut is the process fighters use to drop water weight before a weigh-in, then rehydrate before competition to gain a size and strength advantage. Done correctly, it can be a safe competitive strategy. Done incorrectly, it becomes dangerous — cuts over 8% of body weight significantly increase risk of kidney failure, cardiac events, and performance impairment.
Weight Cut Planner
UFC & Boxing Weight Class Reference
| Weight Class | Lbs Limit | Kg Limit | Sport |
|---|---|---|---|
| Strawweight | 115 | 52.2 | UFC |
| Flyweight | 125 | 56.7 | UFC |
| Bantamweight | 135 | 61.2 | UFC / Boxing |
| Featherweight | 145–126 | 65.8–57.2 | UFC / Boxing |
| Lightweight | 155–135 | 70.3–61.2 | UFC / Boxing |
| Welterweight | 170–147 | 77.1–66.7 | UFC / Boxing |
| Middleweight | 185–160 | 83.9–72.6 | UFC / Boxing |
| Light Heavyweight | 205–175 | 93.0–79.4 | UFC / Boxing |
| Cruiserweight | 200 | 90.7 | Boxing |
| Heavyweight | 265+ | 120.2+ | UFC / Boxing |
How to Use the MMA Weight Cut Calculator
Weight cutting is one of the most debated and potentially dangerous practices in combat sports. Our free MMA weight cut calculator helps fighters plan a structured, evidence-based approach to reaching their target weight class while staying within safe physiological boundaries. Whether you are competing in MMA, boxing, wrestling, or BJJ, the principles here apply across all weight-class sports.
Step 1: Enter Your Current Weight
Use the unit toggle to switch between kilograms and pounds. Enter your current walk-around weight — your weight as measured in the morning after using the bathroom, without clothing. This is your baseline from which the cut is calculated.
Step 2: Select Your Target Weight Class
Choose your target division from the dropdown, which includes all UFC MMA divisions and major boxing weight classes. The calculator converts the class limit to your selected unit system so you always see relevant numbers. If your cut exceeds 10% of body weight, the tool will recommend moving up a weight class.
Step 3: Enter Days Until Weigh-In
How much time you have determines the pace of your cut. With more days, you can use slower, safer methods like diet and controlled water intake. With fewer days (less than 3), you will rely more on acute dehydration methods, which carry higher risk. The calculator adjusts daily targets based on your timeline.
Step 4: Review Your Safety Rating
The MMA weight cut calculator categorizes your cut as Safe (under 5%), Moderate (5–8%), or Dangerous (over 8%). Research published in sports medicine journals consistently shows that cuts over 8% of body weight significantly impair athletic performance even after rehydration, and cuts over 10% have been associated with fatalities in combat sports.
Step 5: Follow the Water Loading Schedule
Water loading (drinking 4–8 liters per day for several days before reducing intake) trains your kidneys to excrete water rapidly. When you reduce intake 24–48 hours before weigh-in, the body continues shedding water at an elevated rate, accelerating the cut. The schedule adapts based on your available days.
Step 6: Plan Your Post Weigh-In Rehydration
The rehydration plan targets replacing 150% of weight lost, spread over the hours between weigh-in and competition. Prioritize electrolyte-rich fluids — sodium, potassium, and magnesium help water enter cells faster. Avoid plain water only, as it can cause hyponatremia if consumed rapidly in large amounts. A staged approach with sports drinks, coconut water, and whole foods produces better results than water alone.
Frequently Asked Questions
Is this MMA weight cut calculator free?
Yes, completely free with no limits or signup required. All calculations run in your browser — your data is never sent to a server.
What is a safe weight cut percentage?
Most sports medicine experts consider cutting up to 5% of body weight relatively safe when done over several days with proper hydration strategy. Cuts between 5-8% carry moderate risk, and anything above 8% is considered dangerous and has been linked to serious health complications including kidney failure and death.
How does water loading work before a weight cut?
Water loading involves drinking significantly more water than normal (4-8 liters/day) for 3-5 days before reducing intake. This trains your kidneys to excrete water at a high rate. When you suddenly reduce water intake 24-36 hours before weigh-in, your body continues excreting water rapidly, leading to faster dehydration and weight loss.
How much water should I drink after weigh-in?
A general guideline is to rehydrate with approximately 1.5 times the weight lost during the cut. For example, if you cut 4 kg, aim to drink 6 liters of fluid (ideally with electrolytes) in the hours between weigh-in and competition. Avoid drinking all at once — spread it over 12-24 hours.
What weight class should I compete at?
The ideal weight class is one where your natural, well-hydrated walking weight is within 5-8% above the limit. This allows a moderate cut while leaving room to rehydrate fully before competition. If your walk-around weight exceeds 10% above a class limit, consider moving up a weight class.
What is the difference between UFC and boxing weight classes?
UFC and boxing share similar weight divisions but with slight differences. UFC uses divisions from Strawweight (115 lbs) to Heavyweight (265 lbs). Boxing has more divisions and historically different names. This calculator shows both UFC MMA and boxing weight classes for reference.
Can I use this calculator for wrestling or judo weight cuts?
Yes, the weight cut principles and safety thresholds apply to any combat sport with weigh-ins, including wrestling, judo, BJJ, and kickboxing. The rehydration and water loading schedules are based on general sports science principles applicable across all weight-class sports.
Is my data private?
Yes. All calculations happen entirely in your browser. Your weight, body composition, and cut plan data are never transmitted to any server or stored anywhere outside your device.