Mum still calls it the 100 watt bulb.
It is a LED now, maybe 9 watt, but the sentence stayed.
The search I get is the old one.
100 watt, how many units in a month.
I do not need a board tariff for that first step.
I need watts, hours, days.
Then divide by 1,000.
A 100 W bulb is small until you leave it on.
Then it is not tiny.
Then it is a habit with a meter.
The school formula I still use
Watts times hours per day times days.
Divide by 1,000.
That answer is units, kWh.
100 times 8 times 30 is 24,000.
Divide by 1,000, 24 units.
At ₹8 a unit, ₹192.
That is the neat story.
If the bulb is on 4 hours, units become 12.
Money ₹96.
If it is on 16 hours, because the passage light never dies, 48 units.
₹384.
Same 100 W.
Hours did the crime.
24 hours, 30 days, 72 units.
₹576 at 8.
I have seen a store room light do that.
Nobody walked in.
Meter still counted.
I open power consumption calculator and type 100, 8, 30, 8.
Units 24.
Rupee 192.
I send the screenshot.
I also say, check the sticker.
If it is LED written 9 W, type 9, not 100.
9 times 8 times 30 / 1000 is 2.16 units.
About ₹17.
That is why people fight.
One person remembers the old filament.
One person bought a LED pack last Diwali.
The word bulb stayed.
The watts did not.
Hours are the part everyone lies about
I lie too.
I say the bathroom light is 10 minutes.
It is not.
Kids leave it.
Guest leave it.
I put 1 hour for bathroom to be less of a fool.
Hall tube, I put 6 in winter, 8 in summer because we sit later.
Study lamp, exam month, 5 hours.
After exam, 0.5, then I forget and it stays in my head as 5.
Next estimate goes wrong.
So I walk the house once.
I write hours like a boring list.
One appliance a time on this tool.
Add the units on paper.
Ten small things can beat one 100 W story.
Two 9 W LEDs all night can still be less than one forgotten 100 W.
I dont romanticise LED.
I just type the sticker.
CFL leftover in a store, maybe 18 W, still not 100.
Tube 36 W, older fat tube 40.
Fan 75 W, some 50.
TV 80 to 120 depending how big and how loud the backlight.
The 100 W search is a teacher.
Once you can do 100, you can do the fridge, with a caveat.
Fridge compressor is not on 24 hours even if the plug is.
People type 150 W and 24 hours and cry.
I type 8 to 12 hours equivalent, or I look at a old bill when only the fridge was home.
Not perfect.
Better than 24.
AC is a different page, 1.5 ton AC for 8 hours.
Dont put 1500 W in this bulb article and mix the moods.
Picture is 100 W, 8 hours, 30 days, rate 8.
24 units.
₹192.
I like that picture because the formula is visible.
No slab.
No city name.
Just the multiply.
If your month is 31 days, type 31.
24 becomes 24.8.
I dont fight over 0.8 units.
I fight over 24 versus 72.
Money needs a rate, units do not
Units come first.
Rate comes from last bill.
If you dont have a rate, read I dont know my unit rate.
Then type it.
24 units at 5 rupee is ₹120.
At 10 rupee is ₹240.
The bulb did not change.
The city rate did.
I still will not paste a DISCOM card.
This tool asks you for the rate.
Fair.
If you only want units, ignore the rupee line.
Landlord who bills per unit still wants units.
24 is the sentence.
If the house has 6 of these old 100 W, and they really are 100, 8 hours each, 144 units.
That is a AC-sized slice.
I ask, are they really 100.
Usually they are not, thank god.
Halogen, some fancy lamp, can be 50 or 75.
Type what is printed.
If nothing is printed, I look at the glass size and still guess low if it is LED shaped.
Guessing high is safer for a budget.
Guessing low is how you get surprised.
I budget high, I sleep.
kW versus W, the box is watts.
1.5 kW means 1500.
If you type 1.5 thinking it is 1.5 kW, the tool thinks 1.5 W, a Christmas fairy.
Result looks free.
It is a unit error.
I did it once with a kettle.
Kettle is 1500 to 2000 W, few minutes a day.
100 W bulb 8 hours can beat a kettle you use twice for tea.
Time on is the hidden boss.
What I add after the one bulb
Standby TV, 2 to 5 W, 24 hours, maybe 2 to 4 units a month.
I add it if I am in a mood.
Wifi router, 8 to 12 W, 24 hours, around 7 units.
Small, until you count three of them.
Laptop 40 to 60 W, office hours at home.
Iron, 1000 W, 15 minutes, not much monthly unless you iron for a army.
Geyser 2000 W, 30 minutes, that one hurts.
2000 times 0.5 times 30 / 1000 is 30 units.
More than the 100 W bulb at 8 hours.
So the bulb article is also a warning.
Dont only hunt the visible lamp.
Hunt the minutes on a fat watt.
I still start people on 100 W because the multiply is clean.
Then I migrate them to the ugly list.
Two meters, run the list per meter.
Paying guest, each room a bulb, add.
Solar, this is consumption, not export.
The meter net is a later story.
I put the monthly units into electricity bill calculator if I want slabs and fixed charge.
24 units alone will not look like a full house bill.
Add the rest.
If the only question is, will one bulb ruin me.
At 8 hours, 24 units, no.
At 24 hours, 72 units, it is a lazy tax.
Switch it off.
Or put a LED and type 9 W.
I am not selling bulbs.
I am showing why the old 100 W sentence still has math.
Watts times hours times days, divide by 1000.
That is the post.
The rest is me stopping you from typing 100 when the sticker says 9, and from typing 24 hours when you dont live in a lighthouse.
Estimate, not official.
Meter wins.
This box only multiplies what you admit.