By far the best solution is to get a FAS-DPD chlorine test, which comes in the better test kits.
However you can get a vague idea of your current FC level by diluting one part of pool water with three parts of distilled water (or other water without any chlorine in it), test that, and multiply the result by four. You lose a substantial amount of precision, with dilution the result is +-6 or worse, but you can get some idea of what your current level is.