How To Measure Weight Without Weighing Machine

Have you ever wondered how to measure weight without weighing machine? Maybe your scale broke, you’re traveling, or you’re just curious. It’s a common question, and the good news is you can get a reasonable estimate using common items you already have at home.

This guide will walk you through several simple household object methods. These techniques use basic physics principles, like leverage and water displacement. They won’t give you a precise digital readout, but they will provide a useful ballpark figure for your weight or the weight of other objects.

The core idea here is to use a known weight to find an unknown one. You’ll be creating a simple balance or using water to find volume. Accuracy depends on your carefulness, but it’s a fun and educational project.

The Core Principle: Using Known Weights

All these methods rely on comparing an unknown weight to something you know. First, you need to find a good reference object. Look for items with a clear weight printed on them.

Bags of flour, sugar, or rice (e.g., 1kg, 5lbs).
Dumbbells or canned goods with the net weight listed.
Full water bottles (1 liter of water weighs 1 kilogram, or 2.2 pounds).

Once you have a known weight, you can use it as your standard. This is the first step in most of the following methods.

Method 1: The Homemade Seesaw Balance

This classic method uses the principle of leverage. You’ll need a long, sturdy object as your lever and a fulcrum (the pivot point).

Find a long, straight board or a broom handle. A 1×4 piece of wood works great.
Place a cylindrical object underneath it as the fulcrum. A soup can, rolling pin, or a round bottle on its side will do.
Position the fulcrum so it’s exactly at the center of the board. Mark this center point.
Place your known weight (like a 2kg bag of sugar) on one end of the board.
Slowly sit or place the object you want to weigh on the other end.
Adjust the position of the known weight or the object until the board balances perfectly level.
Now, measure the distances from the fulcrum to both weights. If the board is balanced, the weight is inversely proportional to the distance.

For example, if your 2kg weight is 30cm from the fulcrum and you are 40cm from the fulcrum, your weight is (2kg * 30cm) / 40cm = 1.5kg. This is a simplified calculation, but it shows the idea. Remember to convert for accurate results.

Method 2: The Water Displacement Tub

This method is best for measuring the weight of solid, non-porous objects. It uses Archimedes’ principle to find volume, which you then convert to weight if you know the material’s density.

Fill a large, deep container (like a plastic storage tub) to the very brim with water. Place it inside an empty larger tub or in the bathtub to catch overflow.
Slowly and carefully submerge the object you want to weigh completely in the full container. Catch all the water that overflows.
Collect the overflow water in a measuring jug. The volume of water displaced (in liters or gallons) equals the volume of your object.
Now, you need to know the density of the object’s material. For example, pure water has a density of 1 kg per liter. Many common materials have known densities you can look up online.
Calculate weight: Volume (in liters) x Density (kg/liter) = Weight in kg. Then convert to pounds if needed (1 kg ≈ 2.2 lbs).

This method is less direct for body weight but excellent for things like a piece of metal or a rock. For body weight, it’s very impractical due to the large volume of water needed.

Finding Density for Common Materials

Water: 1 kg/L
Human Body (approx.): 0.985 kg/L (we float slightly!)
Wood (Oak): ~0.75 kg/L
Steel: ~7.8 kg/L

Method 3: The Bottle and Ruler Scale

This is a more compact version of the balance scale. You’ll create a simple spring scale using a plastic bottle’s elasticity.

Take a clean, empty 1 or 2-liter plastic bottle. A soda bottle with uniform sides is perfect.
Attach a string or wire handle to the bottle’s neck so you can hang it.
Hang the bottle from a fixed point, like a cupboard handle or a rod.
Attach a ruler vertically to the wall behind the bottle, or tape one to the bottle itself for reference.
Mark the bottle’s bottom position on the ruler with no weight. This is your zero point.
Now, hang a known weight (like a 1kg bag) from the bottle’s handle. Mark the new bottom position on the ruler.
Remove the known weight and hang your unknown object. See where the bottom lines up on the ruler.

If the 1kg weight stretched the bottle down 5cm, and your object stretches it 7.5cm, then your object weighs approximately 1.5kg. This method assumes the bottle’s stretch is linear, which is roughly true for small weights.

Method 4: Using Your Own Bathroom Scale (Indirectly)

If you have a bathroom scale but it has a low maximum weight, you can use a clever trick to weigh heavier objects, including yourself with a helper.

Place a strong, flat board (like a piece of plywood) on top of your bathroom scale. This distributes weight evenly.
Step onto the board and note your weight. Let’s say it’s 70kg.
Step off. Now, pick up the object you want to weigh (or have your helper hold it).
Step back onto the board while holding the object. Note the new combined weight. Let’s say it’s 85kg.
Subtract your solo weight from the combined weight: 85kg – 70kg = 15kg. That’s the weight of the object.

This works great for weighing luggage, pets, or large packages. Just ensure the scale and board can handle the total weight safely.

Important Considerations and Safety

These methods are for estimation, not medical or precise measurement. Always prioritize safety.

Check the strength of chairs, boards, and hanging points before use. Don’t overload them.
Be cautious with water to avoid slips and spills.
For the balance methods, ensure the fulcrum is stable and won’t roll away suddenly.
Densities can vary. A wet piece of wood or a hollow metal object will throw off your water displacement calculation.
Accept that there will be a margin of error. Don’t rely on these figures for strict dieting or medical purposes.

Quick Comparison of Methods

Seesaw Balance: Good for medium to larger weights. Requires some math and space.
Water Displacement: Best for small, dense objects. Can be messy and requires density knowledge.
Bottle Scale: Good for light objects. Quick to set up but less accurate.
Scale & Board Trick: Most accurate if you have a working scale. Simple math involved.

FAQ: Common Questions Answered

Can I really measure my body weight with these?

Yes, the Seesaw Balance method or the Scale & Board trick (with a helper) can give you a reasonable estimate of your body weight. The water displacement method is not practical for a person.

What household item is exactly 1 pound?

A full 16-ounce (473ml) water bottle weighs about 1 pound. A standard brick often weighs close to 5 pounds, so one-fifth of that would be tricky, but a pint of water (16 fluid ounces) is a reliable standard.

How can I measure small weights, like for food?

For small weights, use a ruler and a rubber band. Hang the rubber band, mark its length, then hang a known small weight (like a 100g candy bar). Mark the stretch. Compare the stretch when hanging your unknown item. This is a small-scale version of the bottle method.

Why is knowing density important for the water method?

Water displacement only gives you volume. Two objects with the same size (volume) can have very different weights if one is lead and one is wood. Density (mass per unit volume) is the missing link to convert that volume into a weight.

Are these methods accurate for tracking fitness progress?

They can show significant changes (like a loss of 5+ kg) but are not precise enough for tracking small, daily, or weekly fluctuations. For fitness, a consistent method (even an imperfect one) is better than none, but a proper scale is recommended for detailed progress tracking.

While not as convienient as a digital scale, these household methods are a great way to solve a practical problem and understand basic physics. Next time you’re without a scale, try the seesaw balance with a bag of flour. You might be surprised by how close you can get. Remember, the key is using a known weight carefully and double-checking your measurements for the best result.