Calculating GST at 15% - Excel

can someone tell me the excel formula for this, I have tried the web but cant work it out, thanks!

geek_racheal77, Oct 28, 9:17 pm

ROFL, tell me this is a wind up.

geek_lostdude, Oct 28, 9:18 pm

To find the GST on a gst ex price multiple by 0.15. To find the gst ex amount on a gst inc price, divide by 1.15. Why oh why peopl bother using meanless fractions is beyond me, at least the decimals make sense.

geek_rgtrading, Oct 28, 9:22 pm

What are you even doing using excel if you can't even comprehend such basic math? I'm not being sarcastic, that's a genuine question.

geek_ross1970, Oct 28, 9:28 pm

except if you use the decimals amount you suggest.

Price including GST = price x 1.15

geek_malachiman, Oct 28, 9:33 pm

+1on that one


geek_drcspy, Oct 28, 9:34 pm

xxx*1.15 to add on where xxx is the $ value
xxx/1.15 to take it off

geek_cursedone, Oct 28, 9:57 pm

Have you learned about the on/off button on the front of your computer yet?

geek_ngubb, Oct 28, 10:09 pm

^^ this is basic maths

geek_johnf_456, Oct 28, 10:12 pm

Here's the formula used to work out the GST content of a GST inclusive price when the GST content is 15%

Multiply the full GST inclusive price by 3 then divide that result by 23. The end result will be the GST amount.

geek_ilottl, Oct 28, 11:37 pm

Um no - x 0.15 WILL work out the GST on the GST ex amount - x 1.15 will work out the GST inc amount.

geek_rgtrading, Oct 29, 7:46 am

A meaningless fraction - how is the average Joe Blog supposed to relate 3/23 to 15%? Yes it works, but its a recipe for trouble. 0.15 = 15% so at least that makes sense.

geek_rgtrading, Oct 29, 7:48 am

The average Joe Blogs has been a failure of or a failure in the education system if they don't understand fractions.As must those who think percentages (a fraction out of 100) or mentally unwieldy and less accurate decimals are better and easier.

geek_cybertao, Oct 29, 8:01 am

All of this can be found out, there is many goggle calculators

geek_johnf_456, Oct 29, 8:14 am

Yes, fractions can be less accurate, but in this case, 0.15 is as accurate as you are going to get. Yes, 3/23 also works, but neither 3 nor 23 directly have anything to do with 15%, so you can guarantee a lot of people will get confused or just plain forget.

geek_rgtrading, Oct 29, 8:27 am

Really?What's 3/20?
GST adds 3/20ths to the price. To take it off you subtract 3/23rds or or just find 20/23rds.
Easy when you understand, percentages and decimals are just as hard to work with when you don't.

geek_cybertao, Oct 29, 8:39 am

3/23 is blooooody confusing. It might be the easiest answer but it's not obvious how it relates to 15% at all, much clearer if you express it as 15/115 that's the GST part (15%) of the total post-GST price (which is 115% of the pre-GST price)

geek_little_egypt, Oct 29, 8:40 am

15/115 is exactly the same as 3/23 and requires the same basic numeracy skills.If you don't have basic numeracy skills, get someone else to do your taxes.

geek_cybertao, Oct 29, 8:50 am

Had to happen. Knew this thread was going to end in the big 3, 20, 23 saga. Using fractions when gst was just 12.5 was relevant if you wanted being an easy 1/8th, it was "understandable". Anyone using fractional calculations now is just complicating things for the hell of it.

geek_ross1970, Oct 29, 8:51 am

Heh this is FUNNY. First the OP gets slagged for asking the question, but then an argument starts over what they've been told.....

"No such thing as a stupid question, only stupid answers" springs to mind.....

geek_smac, Oct 29, 10:35 am

errmmmmmmmmm really ?

geek_drcspy, Oct 29, 10:52 am


anyone who has such a poor undertanding of maths that they cant calculate the price of something either including gst or excluding it or the gst proportion of a price............needs their head read...........and when they need to ask well maybe it's not necessarily a 'stupid question' - just a question from stupid person ?

geek_drcspy, Oct 29, 10:53 am

LOL, yeah it will be confusing to those that don't even know year 3 maths but for the rest of us, it's not that hard to derive that 3/23 is the reduced fraction of 15/115. I must agree with cyber on this one. I sometimes wonder how people get their jobs...

geek_lostdude, Oct 29, 11:27 am

15/115 - two extra keystrokes make it a 'self documented' formula.

geek_r.g.nixon, Oct 29, 11:30 am

...for someone who understands what it is for and how it works...someone with basic numeracy skills.

geek_cybertao, Oct 29, 11:47 am

What rg says; leave the fraction as 15/115 or 15/100 and it's immediately obvious. Reduce it to 3/23 or 3/20 and most people will be scratching their head for a few minutes trying to figure out where that ratio comes from. Remember that half the population have below-average skills in maths.. and I don't think the average is all that high either.

geek_little_egypt, Oct 29, 11:56 am

I think the OP was asking for the EXCEL formula, something like this =A1 * (1 + .15)?

geek_cherise11, Oct 29, 12:15 pm

It wouldn't surprise me if there were people who don't realise that you can use a pen and paper (or your head) to do Math. "You mean you can do this without a calculator or a computer ?!?"

geek_badcam, Oct 29, 12:26 pm

yep stillbloody simple tho

geek_drcspy, Oct 29, 12:40 pm

racheal77 IRD have a free downloadable cashbook here here select Record Keeping/Other Books/Cash Book/Sample Cah Book (you will need a flash player). In Excel click on the Formulas ribbon, highlight GST Received or GST Paid then in the Formula Auditing section click Show Formulas. I hope this helps.

geek_cherise11, Oct 29, 12:46 pm

I'm using MS Office 2007 btw

geek_cherise11, Oct 29, 12:48 pm

wtf ? Decimals can't represent a third as accurately as 1/3

geek_damon3, Oct 29, 2:00 pm

Yeah.Some people have problems with basic maths.Others struggle with basic English!

geek_radiowaves, Oct 29, 2:15 pm

I see what you're getting at but they can:3?¹

geek_ross1970, Oct 29, 2:20 pm

Hi there.I have been reading some of the feedback you have been getting, and I am a little annoyed to be honest.Don't we have this community message board for a reason??Who are all these people that feel they can judge your question?I am assuming they know everything there is to know.It would be a sad day when they needed to ask a question they thought was difficult and got shot down by someone who knew the answer.Chill out people.

geek_mumz31, Oct 29, 2:25 pm

# 36- welcome to the internet...

geek_damon3, Oct 29, 2:29 pm


geek_ross1970, Oct 29, 2:37 pm

+1 , times 1.15

geek_johnf_456, Oct 29, 2:40 pm

Are you digging at me?

geek_johnf_456, Oct 29, 3:22 pm

Fixed that for you.

geek_cybertao, Oct 29, 3:25 pm

LOL my calculation is right, depends what you want to calculate in gst. Add on, gst amount...

geek_johnf_456, Oct 29, 3:27 pm

talk about turning a simple question in to a bun fight.
poster 1:
If you want to extract the GST amount in excel - just divide by
eg 115.00divided by 7.66666 = 15.00 which is the gst content of

geek_honeybean, Oct 29, 3:39 pm

That's what they said.

geek_biker_69, Oct 29, 3:48 pm

Anyone who wants to confuse themselves with 3/23 or 1/9 or 8/9 is welcome to do so. But I do percentages the proper way using decimals. 15.23568% of $80 = 0.1523568 x 80. Simple and accurate.

geek_biker_69, Oct 29, 3:50 pm

+1 Easy peasy.

geek_johnf_456, Oct 29, 3:53 pm

Racheal Its quite common to get your head bitten off by the wankers on here. Sorry it had to be you this time. Hope you can get your head backon straight.

geek_biggal, Oct 29, 4:24 pm

hahahaha definitely some funny s^%$@! going on here!!!
The initial question reads like a Certificate in Business Administration & Computing Course question...hmmm

geek_widoolz, Oct 29, 4:29 pm

Incorrect.The IRD stipulate that you must use a minimum of 8 decimal places.

geek_radiowaves, Oct 29, 4:29 pm

typo, I meant decimals. However, 0.15 and 1.15 are a lot easier to remember for most people than 3/23 surely.

geek_rgtrading, Oct 29, 6:04 pm


geek_biker_69, Oct 29, 6:55 pm