Ever wondered how to know weight without weight machine? It’s a common situation, whether you’re traveling, at home without a scale, or just curious. You can get a surprisingly good estimate using simple methods and common objects.
These techniques rely on physics principles like displacement and leverage. They won’t give you a doctor’s-office precise number, but they’ll provide a useful ballpark figure. Let’s look at several ways you can try.
How To Know Weight Without Weight Machine
This main method uses water to measure your volume, which we then convert to weight. It’s science you can do at home. You’ll need a bathtub, a large, see-through container if your tub isn’t marked, and a marker.
The Water Displacement Method
This works because it measures your body’s volume. Since the density of the human body is close to that of water, we can make a close calculation.
- Fill your bathtub until it’s about halfway full.
- Carefully get into the tub and submerge yourself completely. Have a friend mark the new water level on the side of the tub with a waterproof marker or tape.
- Get out of the tub carefully, trying not to splash water over the mark.
- Now, use a large measuring jug or bucket with known volumes (like gallons or liters). Fill it and add water to the tub until it reaches the mark you made. Count how many jugs it takes.
Now for the math. One liter of water equals one kilogram in weight. So, if you displaced 70 liters of water, your approximate mass is 70 kilograms. To get pounds, multiply the kilograms by 2.2. So 70 kg x 2.2 = approximately 154 pounds.
Using a Seesaw or Homemade Lever
This classic physics experiment uses a known weight to find an unknown one. You’ll need a long, sturdy board (like a 2×4), a fulcrum (a saw horse or a log), and an object you know the weight of.
- Place the board balanced on the fulcrum, exactly at its center point.
- Have the person of unknown weight sit on one end. The board will tip down on their side.
- Now, slowly add your known weights (like bags of flour, books with known weight, or gym dumbbells) to the other end untill the board balances level.
- Add up the total known weight on that end. That total is roughly equal to the person’s weight, assuming the board is perfectly balanced and even.
For more accuracy, you can adjust the fulcrum’s position. This is similar to how a traditional scale with sliding weights works.
Finding Known Weights Around the House
You need reference objects. Here are common items with standard weights:
- A standard bag of all-purpose flour or sugar: 5 lbs (2.26 kg).
- A gallon of milk or water: 8.34 lbs (3.78 kg).
- A standard ream of printer paper (500 sheets): 5 lbs (2.26 kg).
- A 10-lb or 5-kg dumbbell or weight plate.
- A liter of soda or water: 2.2 lbs (1 kg).
Estimating with Body Measurements
This method uses formulas based on your body’s circumferences. You’ll need a soft measuring tape. Accuracy varies based on body composition, but it gives an estimate.
- For men: Measure your waist at the navel.
- Use this formula: (Waist in inches x 4.15) – 98.42 = Approximate weight in pounds.
- For women: Measure your waist, wrist, hip, and forearm at their fullest points.
- Use this formula: (Waist x 4.15) + (Hip x 2.54) – (Wrist x 2.71) – 98.42 = Approximate weight in pounds.
Remember, muscle is denser than fat, so a very muscular person might weigh more than this formula suggests. It’s just one data point.
Using Clothing Fit as a Guide
While not numerical, your clothes offer consistent feedback. Pick a few key peices, like a pair of jeans or a fitted jacket, that fit you well at a known weight.
- Try them on periodically. How they fit—tight, loose, or just right—can indicate weight change.
- This is best for tracking loss or gain rather than finding an exact number.
- Different brands fit differently, so stick to the same brand for comparison if you can.
The Phone App Alternative
Several smartphone apps claim to estimate weight using your phone’s sensors. The method is often questionable, but some use pictures or measurements.
- Photo-based apps: You take a picture of yourself against a reference object. Their accuracy is generally low and depends on lighting and angle.
- Measurement-based apps: You input your height and body circumferences, and they use a formula similar to the one above. These can be slightly more reliable.
- Be skeptical of any app that claims to use your phone’s accelerometer or screen to measure weight directly—this is not physically possible.
Comparing to a Known Person’s Weight
This is a very rough method, but it can work in a pinch. If you have a friend who’s weight you know and who has a similar build, you can do a simple comparison.
- Stand next to each other in front of a mirror.
- Look at differences in frame size, muscle definition, and overall size.
- You could also gently lift similar objects, then lift each other to feel the difference in effort required. This is highly subjective though.
It’s easy to misjudge, so don’t rely on this for any serious assessment. Body composition makes a huge difference here.
For Weighing Objects, Not People
Need to weigh a package or a suitcase? Here’s a simple trick with a ruler and a known weight.
- Place a ruler on a table, with about 2 inches hanging over the edge.
- Place your known weight (e.g., a 1-lb can of food) on the short end that’s on the table.
- Hook the object you want to weigh (like a small bag) on the end hanging off the table.
- Adjust the position of the ruler on the table until it balances.
- Measure the distance from the fulcrum (table edge) to each object. The formula is: (Known Weight x Distance from Fulcrum) = (Unknown Weight x Its Distance from Fulcrum). Solve for the unknown weight.
Why These Methods Aren’t Perfect
It’s important to understand the limitations. Human body density isn’t always exactly like water’s—bone and muscle density vary. Lever methods assume perfect balance, and household items aren’t always precisely the weight stated. These methods are for estimation, not medical diagnosis. For clinical accuracy, a calibrated scale is nessecary.
Tracking Progress Without Numbers
If you’re focused on fitness, weight is just one metric. Consider these non-scale victories:
- How your clothes fit and feel throughout the day.
- Increased energy levels and endurance during activity.
- Improved strength, like lifting heavier groceries or climbing stairs easier.
- Better sleep quality and general mood.
- Body measurements with a tape showing inches lost.
These signs are often more meaningful than a number on a scale. They reflect overall health better sometimes.
Frequently Asked Questions (FAQ)
Can I really measure my weight with water?
Yes, the water displacement method provides a good estimate. It measures your volume, and because the human body’s density is close to water’s, you can convert liters to kilograms directly. Just be precise with the water level marking.
What is the easiest way to guess my weight?
The easiest way is to use the body measurement formula (for men: waist in inches x 4.15 minus 98.42). It only requires a measuring tape. The lever method is more accurate but requires more setup and a known weight to compare against.
How can I find out how much I weigh for free?
All the methods described here are free. Use items you already have at home: a bathtub, a board, bags of flour, or a measuring tape. Public places like gyms, drugstores, or doctor’s offices sometimes have scales you can use for free as well, if you ask politely.
Is there a way to measure weight with your phone?
Your phone cannot directly measure weight. Some apps use photos or inputted measurements to estimate, but they are not very accurate. Be wary of any app that claims otherwise; it’s likely not truthful about its methods.
How did people weigh themselves in the old days?
Historically, balance scales with stones or standardized metal weights were used. The lever principle has been understood for thousands of years. People would also compare goods against known standards, like bags of grain, much like the homemade lever method described.
Can I use a regular tape measure to estimate weight?
Absolutely. The formulas that use waist, hip, and wrist measurements rely on a regular soft measuring tape. Make sure you measure at the correct points and keep the tape snug but not tight for the most consistent result. Write the numbers down so you don’t forget them.
In conclusion, while not as convienient as a digital scale, these methods show you can get a reasonable idea of your weight using creativity and basic physics. Whether you choose water displacement, a homemade balance, or a simple formula, you now have options next time you’re without a scale. Remember, these are estimates, and for most general purposes, they provide enough information to be helpful.