How To Know Weight Without Weighing Machine

Sometimes you need to know your weight, but a scale just isn’t around. Learning how to know weight without weighing machine is a useful skill, and there are several simple ways to estimate it. This guide will walk you through practical methods you can use at home or on the go.

These techniques rely on common objects and basic math. They won’t give you a doctor’s-office precise number, but they’ll provide a good ballpark figure. This is helpful for tracking general trends or when you’re traveling.

Before we start, remember these are estimates. For medical purposes, always use a calibrated scale. But for a general idea, these methods work surprisingly well.

Method 1: The Water Displacement Trick (Bathtub Method)

This uses Archimedes’ principle. It sounds scientific, but it’s straightforward.

Fill your bathtub to the very brim. Sit in it carefully and get completely submerged. Water will overflow.
Step out carefully. The water level will now be lower.
Use a known container (like a gallon jug) to refill the tub exactly to the brim again. Count how many gallons it takes.
Multiply the number of gallons by 8.34 (the weight of one gallon of water in pounds). This number is a close estimate of your body weight in pounds.

For kilograms, remember one liter of water weighs one kilogram. If you measure in liters, that’s your weight in kg.

Method 2: Using a See-Saw or Homemade Lever

You can create a simple balance scale. You’ll need a long, sturdy board and a fulcrum (like a sawhorse or a log).

Place the board centered on the fulcrum so it balances like a see-saw.
Have a friend whose weight you know sit on one end.
You sit on the other end. Adjust your positions until the board balances perfectly.
Use the physics formula: (Your Distance from Fulcrum) x (Your Weight) = (Friend’s Distance) x (Friend’s Weight).
If your friend weighs 150 lbs and is 4 feet from the fulcrum, and you are 3 feet from the fulcrum when balanced, your weight is (150 x 4) / 3 = 200 lbs.

Method 3: Estimation by Body Measurements

This method uses your body’s dimensions. You’ll need a soft measuring tape.

For Men:

Measure your waist at the navel.
Measure your wrist at its smallest point.
Formula: (Waist in inches x 4.15) – (Wrist in inches / 0.082) = Approximate weight in pounds. Then divide by 2.2 for kg.

For Women:

Measure your waist at the smallest point.
Measure your wrist, hip, and forearm at their fullest points.
Formula: Multiply your wrist measurement by 0.732. Add 8.987. Divide your waist measurement by 3.140. Divide your hip measurement by 0.249. Divide your forearm measurement by 0.434. Add the first two results, then subtract the last three results. The answer is your lean body mass. You then need to calculate body fat percentage to add to it, which is more complex.

Because the women’s formula is tricky, online body fat calculators that use measurements are often easier.

Method 4: The Known Object Comparison

This is a relative method. Find an object with a known weight that you can lift comfortably.

Choose an item, like a 20-pound dumbbell or a 10-pound bag of flour.
Lift it with one hand. Now, lift yourself with the other hand on a sturdy bar or ledge (like a pull-up bar).
Compare the feels. How much heavier does your body feel? If your body feels about ten times heavier than the 10-pound bag, you might be around 100 pounds.
This requires some guesswork, but with practice, you can get decent at comparing relative weights.

Method 5: Using a Regular Tape Measure and Online Calculators

This is one of the most accessible methods. The U.S. Navy and other organizations have formulas based on measurements.

Take accurate measurements: Height, neck, and waist for men. Height, neck, waist, and hips for women.
Search for “U.S. Navy body fat calculator” online.
Input your measurements. The calculator will estimate your body fat percentage.
With your body fat percentage and your height, you can then use a second weight calculator to estimate your total weight. Many sites combine these steps.

This method’s accuracy depends on how correctly you take the measurements. Have someone help you for the best results.

Method 6: Smartphone Apps (Indirect Measurement)

Some modern smartphone apps claim to estimate weight using the phone’s sensors. They work by having you place the phone on a surface and perform movements.

The science behind these is often questionable. Their results can vary widely based on the phone model and how you perform the test. I wouldn’t rely on them for accuracy, but they can be a fun experiment. They’re better for tracking relative change over time if you use the same phone and method each time.

Why Clothes Fit is a Good Long-Term Indicator

While not a number, how your clothes fit is a fantastic daily indicator. Pick a pair of pants or a belt as your benchmark.

Is the belt notch moving? That shows change.
Are your jeans feeling looser or tighter? This reflects real-world changes in your body size and composition, which is often more meaningful than weight alone.

Muscle is denser than fat, so you might get leaner without the scale moving much. Your clothes will tell that story better than any number.

Tracking Progress Without a Scale

Weight is just one metric. Here are other ways to track your fitness journey:

Progress Photos: Take front, side, and back photos every two weeks in consistent lighting and clothing.
Measurement Tracking: Record your chest, waist, hip, arm, and thigh measurements every month.
Strength Gains: Can you lift heavier, do more push-ups, or walk further? That’s real progress.
Energy Levels: Do you have more stamina during the day? That’s a huge win.

These methods often give a more complete picture of your health than a scale ever could. They help you focus on performance and feel, not just a number.

Important Limitations and Safety Notes

Remember, these are estimation techniques. They have margins of error.

Do not use these methods for medical dosing or if precise weight is critical for health reasons.
Fluctuations are normal. Hydration, food intake, and sodium can change your weight by several pounds daily.
If you’re tracking for fitness, weigh yourself at the same time of day (morning, after bathroom, before eating) for the most consistent readings, even with a real scale.
Focus on long-term trends, not daily numbers. A general downward or stable trend over weeks is what matters.

FAQ

How can I find out my weight without a scale?
You can use the water displacement method, a homemade balance with a friend of known weight, or body measurement formulas. These provide a close estimate.

What is the most accurate way to guess your weight?
The water displacement (bathtub) method and the body measurement formulas (like the Navy method) tend to be the most accurate of the at-home, no-scale options, as they rely on physics and standardized calculations.

Can I use a tape measure to calculate weight?
Yes, but not directly. A tape measure gives you body dimensions. You then input those into an online body composition calculator, which estimates body fat and, subsequently, weight.

How did people weigh themselves in the old days?
They used balance scales with known counterweights. The principle is the same as the see-saw method—comparing an unknown weight to a series of known weights until balance is achieved.

Is there a app to check weight?
There are apps that claim to estimate weight using phone sensors, but their accuracy is generally poor and not reliable for serious tracking. They are more for novelty.

Why do my clothes feel tighter but the scale doesn’t change?
This is common! It often means you’re losing muscle (which is dense and takes up less space) and gaining fat (which is less dense and bulky). This is why tracking measurements and photos is so important alongside weight.

In conclusion, while a scale is a precise tool, you’re not completely without options when one isn’t available. By using principles of physics and simple math, you can get a reasonable idea of your weight. The key is to use consistent methods if you’re tracking over time. And remember, how you feel, how your clothes fit, and what you can do are ultimately the best measures of your health and fitness.