How To Find Subtotal & What Sales Tax Amt From A Total?

If you know the sales   tax percentage, you can work out the subtotal and sales tax amount from the total. There's surely an actual formula for this somewhere, but this works.

Say the sales tax is 9.3 percent. You divide your grand total by 1.093 to get the sub total. ( .093 is 9.3% expressed as decimal number)

Example: \$7.10 is the grand total. Tax is 9.3%.
\$7.10 / 1.093 = \$6.4958828   (\$ 6.50)

This is your sub-total. To find the sales tax amount, simply subtract your sub from the grand.

\$7.10 - \$6.50 = \$0.6041172   ( \$0.61)

This is your sales tax amount.
thanked the writer.
If you know the sales tax percentage, you can work out the subtotal and sales tax amount from the total. There's surely an actual formula for this somewhere, but this works.

Say the sales tax is 9.3 percent. You would multiply the sub total by .093 to get the sales tax.
You want to take the grand total and multiply by .907 because .093 + .907 gives you 100%.

Example: \$7.10 is the grand total. Tax is 9.3%.
\$7.10 x 0.907 = \$6.44

This is your sub-total. To find the sales tax amount, simply subtract your sub from the grand.

\$7.10 - \$6.44 = \$0.66

This is your sales tax amount.
thanked the writer.
Anonymous commented
I'm trying to figure out the exact thing, but I believe something is wrong with your method. To check my work, if \$6.44 is the subtotal then you would multiply \$6.44 by the tax rate, and add it back to the sub. This should equal your total (\$7.10)... I did this but for some reason, it does not add up:
6.44 x .093 (tax rate) = .60
6.44 + .60 = 7.04, not the original amount of 7.10... I don't know any other method, so I can't poke holes in yours; maybe I'm not doing something right? 