I'm assuming an IQ distribuition with a mean of 100 and a standard deviation of 15 (μ=100, σ=15). That's what most modern IQ tests use. If your test is based on a different distribution, subtract the mean of your test (this will probably still be 100), divide by the σ of your test, multiply by 15 and add 100.

E.g., if your test uses μ=100, σ=12 and your score is 140, do:

140 − 100 = 40
  40 / 12 = 3.33
3.33 × 15 = 50
 50 + 100 = 150

In this case, 150 would be your score translated to μ=100, σ=15.

Here you can go back to the calculator, but use the "back" button if you want to preserve your entries.