Friday evening he sent a maps screenshot.
240 km.
One way.
He wanted petrol money before he promised the weekend.
I did not open a oil company circular.
I asked three things.
Distance you will actually drive.
Mileage the car gives you, not the brochure.
Pump price on the board today.
Distance over mileage times price.
That is the whole kitchen formula.
Wrong mileage is how this number goes crazy.
I have a separate rant on typing 1.6 instead of 16.
This page is the 240 km story with honest boxes.
The three numbers, in the order I ask
Distance first.
240 km if it is one way and he is not coming back the same wallet.
480 if it is return on the same trip budget.
People send 240 and then also come back.
They under-save by half.
I ask, are you sleeping there.
If yes, still 480 of road unless someone else drives the return in their car.
I add a bit for city roam, hotel to fort, 20 km extra, sometimes 40.
Maps is the highway.
Weekend is not only the highway.
So I might type 260 one way, 520 return, if I know this cousin.
Mileage second.
Brochure 22 km per litre.
His city mix 14.
Highway maybe 17, 18 if the right foot is calm.
I ask what the last full tank did.
Trip meter, litres filled, simple divide.
If he never tracked, I put 16 for a small petrol car as a middle.
Not a lab.
16 is a peace number.
If it is a thirsty older petrol, 12.
If it is a careful diesel highway, maybe 20, but then the price box is diesel price, not petrol.
CNG is km per kg and price per kg.
Same shape.
Price third.
I tell him to look at the pump board, not last month memory.
Petrol moves.
₹100 a litre is a easy teaching price.
Your city might be 96 or 104 the week you travel.
Type that.
I dont freeze a India-wide petrol rate on this site.
The fuel cost calculator waits for your pump number.
240 divided by 16 is 15 litres.
15 times 100 is ₹1,500.
That is the WhatsApp reply I like.
15 times 104 is ₹1,560.
Still the same 15 litres.
Price changed, litres did not.
If mileage is 12, litres become 20.
20 times 100 is ₹2,000.
Same 240 km.
See why I nag about mileage.
If mileage is 20, litres 12, money ₹1,200 at 100.
The trip did not shrink.
The engine story did.
Worked 240, and the return I keep repeating
I put 240, 16, 100 in the tool.
Fuel 15 L.
Money ₹1,500.
I say, this is one way.
He says, obviously return.
I say, then type 480, or run twice.
480 / 16 is 30 litres.
₹3,000 at 100.
That jump shocks people who planned 1,500 for the whole outing.
I would rather shock on Friday than on Sunday night at a empty pump.
Toll is not in this box.
Parking not in this box.
One chai stop not in this box.
Add those in the head.
I add ₹400 toll if I know that stretch, sometimes more.
The tool stays fuel only.
Two people splitting fuel, do the fuel first, then split bill.
₹1,500 split two ways is 750 each, if they agreed fuel only.
If one guy ate the toll, write that down before the fight.
The picture is 240 km, 16 km/l, ₹100.
15 litres.
₹1,500.
I like teaching with 100 because the money equals litres times 100, easy check.
If your pump is 98.4, type 98.4.
Dont round to 100 and then argue 24 rupees.
24 rupees is a snack.
Unless the group is the type that argues snacks.
Then type exact.
Highway mileage better than city, yes often.
If 240 is almost all highway, I might put 18 instead of 16.
240 / 18 is 13.33 litres.
About ₹1,333 at 100.
If 240 is ghat plus AC plus boot full of bags, I put 14.
About 17.1 litres, ₹1,714.
I would rather carry ₹2,000 cash or a card limit than land short.
Spare 5 litres in the head.
This is still estimate, not a oil company receipt.
Where the result explodes, I have seen it
Mileage 1.6 instead of 16.
240 / 1.6 is 150 litres.
Times 100 is ₹15,000.
He called me thinking the car is broken.
Decimal.
I wrote I put wrong mileage and trip cost went crazy after the third time.
Price 1000 instead of 100, extra zero, same horror.
Distance 2400, extra zero, ten times fuel.
Distance 24, missing zero, looks like a free trip.
I check those three boxes like a airport dad.
AC on, four people, roof carrier, mileage drops.
I drop the km/l by 1 or 2.
I dont have a weather slider.
Tyres low, I nag about safety, then I still drop mileage a bit.
Bike 240 km, mileage maybe 40, litres 6, money ₹600 at 100.
Different machine, same formula.
I dont want bike people using 16.
16 is a car peace number, not a law.
Company car, if fuel is billed to office, this math is still useful to see if the claim looks sane.
If claim is 40 litres for 240 km, someone is dreaming or taking a longer road.
240 / 40 = 6 km per litre, a truck mood.
Ask.
Empty tank start, you may buy more than the trip burns, because you also fill what was missing.
The trip burn is still 15 litres in the 16 km/l story.
The receipt can be 25 if the tank was low.
Dont confuse fill amount with trip amount.
I explain that slowly because it causes 80 percent of the family arguments.
How I use the boxes on this site
I open fuel cost calculator.
Distance, 240 or 480.
Mileage, honest.
Fuel price, today.
Calculate.
I read litres and money.
I say estimate.
Pump meter will differ a little, rounding, temperature, how full is full.
A 3 percent gap I ignore.
A 30 percent gap, mileage was fantasy or distance was one way.
If he wants diesel vs petrol, I run twice with two prices and two mileages.
I dont keep a official price table.
If he wants to see the dinner after the drive, that is dinner 2,860 split, different wallet.
Fuel first.
Food later.
I pack a extra 200 rupee in my head for the last town pump being dearer.
Border towns do that.
Tool cannot see the border.
I still use 240 as the teaching distance because maps love that number on a Saturday.
Your trip might be 187.
Type 187.
The formula does not need a round number.
Distance over mileage times pump price.
I will say it till it sticks.
And I will not pretend I know your car better than your last tank.
Last tank is the adult.
This page is the preview so you dont leave home with ₹500 and a optimistic brochure.