this post was submitted on 02 Nov 2025
50 points (90.3% liked)

Life Pro Tips

3174 readers
1 users here now

Unlocking the Secrets to Success and Fulfillment!

Rules

  1. Share valuable life pro tips.
  2. Keep it concise and clear.
  3. Stay on-topic.
  4. Respect fellow members.
  5. No self-promotion.
  6. Verify information before sharing.
  7. Avoid illegal or unethical advice.
  8. Report rule violations.

Join us and share your best life pro tips!

founded 2 years ago
MODERATORS
sabbah@lemmy.world
HonoraryMancunian@lemmy.world
50
LPT: Easy way to convert Celsius to Fahrenheit (lemmy.world)
submitted 3 weeks ago by xylogx@lemmy.world to c/lifeprotips@lemmy.world
17 comments fedilink hide all child comments
 

Double the number, then reduce by one-tenth the doubled number, then add 32

Example: To convert 25 C double it to 50, reduce by 5 to get 45, then add 32 to get 77 F.

The reason this works is because 9/5 = 10/5 - 1/5. And the nice thing about this is that it is an exact conversion not an estimation.

top 17 comments
sorted by: hot top controversial new old
[–] ook@discuss.tchncs.de 31 points 3 weeks ago (1 children)

"Easy"

[–] xylogx@lemmy.world 10 points 3 weeks ago (1 children)

Ok maybe a bit of a stretch, but definitely easier than directly calculating 9/5ths.

[–] panda_abyss@lemmy.ca 11 points 3 weeks ago (1 children)

9/5 is easy though, you double then subtract a tenth

[–] MoreZombies@quokk.au 18 points 3 weeks ago

Why would I want to convert TO Fahrenheit? =/

[–] hypeerror@sh.itjust.works 11 points 3 weeks ago

every 10 degrees Celcius is 18 Fahrenheit.

0c is 32

10 c is 32 + 18 or 50f

20c is 50 + 18 or 68f

30c is 68 + 18 or 86f

40c is 86 + 18 or 104f

Congrats you can now dress comfortably when you travel.

[–] iAmTheTot@sh.itjust.works 8 points 3 weeks ago* (last edited 3 weeks ago)

It's even easier to skip the "reduce by 1/10" step and you still get close. It gets less and less accurate the larger the number becomes, but most people are doing this for day-to-day outdoor temps and it's more than good enough for that to get close. Maybe don't rely on it for baking, though.

edited to add, also instead of "adding 32" it's often easier to think about just adding 30.

[–] bdonvr@thelemmy.club 4 points 3 weeks ago (1 children)

That's neat but I definitely won't remember

[–] xylogx@lemmy.world 2 points 3 weeks ago

If you do not need this often, it is hard to remember. I work with many foreign countries, so I need this often.

[–] BeigeAgenda@lemmy.ca 4 points 3 weeks ago

Is searching for "25 C in F" considered cheating?

[–] BlueberryWalnut@sopuli.xyz 3 points 3 weeks ago

Just double it

[–] bdonvr@thelemmy.club 2 points 3 weeks ago (1 children)

What about negative numbers

[–] xylogx@lemmy.world 2 points 3 weeks ago (1 children)

Works just the same:

-10 C doubles to -20, reduce by -2 to -18, and add 32 to get 14 F.

[–] bdonvr@thelemmy.club 2 points 3 weeks ago

I think I was getting confused with the "reducing" a negative number. But yeah reducing a negative negatively moves it positively

[–] InvestBurnout@fedia.io 2 points 3 weeks ago (1 children)

I always multiply by 2 and add 30

[–] SanctimoniousApe@lemmings.world 2 points 3 weeks ago

Good enough for estimating, but not accuracy.

[–] sin_free_for_00_days@sopuli.xyz 2 points 3 weeks ago

I rarely care about the actual number. "Cold", "Not bad", "Warm", and "Hot" cover 99% of my weather related temperature interactions. I have also memorized 3 easy conversion points to estimate from if I care. If I really care...well I don't think that I ever have. Maybe cooking instructions, then I might care, but even that is usually just by feel. I'm not a baker.

10C = 50F 
28C = 82F
40C = 104F