Softonic

Antilog Calculator

Step 1 / 3 Antilogarithm

The antilogarithm reverses a logarithm: if log_b(x) = y, then the antilog of y is x = b^y. Enter the value (your exponent), pick the base — 10, e, 2 or a custom base — and the calculator raises that base to your value. It is handy for reading log tables backwards, converting pH or decibels back to linear units, and checking exponent homework without a scientific calculator.

How to find an antilogarithm

  1. 1

    Enter the value

    Type the exponent y — the logarithm whose antilog you want. It can be negative or a decimal.

  2. 2

    Pick the base

    Choose base 10 (common antilog), e (natural), 2 (binary) or a custom base b > 0.

  3. 3

    Read the antilog

    The tool returns b^y, switching to scientific notation when the number is very large or very small.

Definition

The antilogarithm is simply the inverse of the logarithm:

antilog_b(y) = b^y

So if log_b(x) = y, then x = antilog_b(y) = b^y. The “value” you enter is the logarithm y, and the “base” is the same base b you would have used for the original log.

Worked example

Suppose a log table gives you log₁₀(x) = 2.5 and you want x.

x = antilog₁₀(2.5) = 10^2.5 = 10^2 · 10^0.5 ≈ 100 · 3.1623 ≈ 316.23

So the original number was about 316.23. You can verify it: log₁₀(316.23) ≈ 2.5.

Antilog of common values

Base Value (y) Antilog (b^y)
10 0 1
10 1 10
10 2.5 316.2278
e 1 2.7183
e 0 1
2 10 1024
2 0.5 1.4142

Common pitfalls

  • Mixing up the base. The antilog must use the same base as the original log. An antilog with base 10 of a natural-log value gives the wrong number.
  • Sign of the exponent. A negative value gives a result between 0 and 1 (for bases above 1), never a negative number — b^y is always positive for a positive base.
  • Custom base ≤ 0. A base of zero or a negative base is not defined for general real exponents; keep b > 0. Base 1 is allowed but always returns 1.
  • Huge or tiny outputs. Large exponents (for example 10^40) overflow ordinary display, so the result is shown in scientific notation rather than rounded to zero or infinity.

Frequently Asked Questions

It is the inverse of a logarithm. If you took the log of a number to get y, the antilog of y gives back the original number: antilog_b(y) = b^y.

A logarithm asks “what exponent gives this number?” while an antilog asks “what number does this exponent produce?” They undo each other for the same base.

No. For any positive base, b^y is always positive. A negative value of y just produces a small positive fraction between 0 and 1.

No. The calculation runs in your browser as you type and nothing you enter is uploaded, saved or shared.

Related Tools

BMI Calculator

Calculate body mass index from height and weight. Shows WHO category, healthy-weight range and limitations of BMI.

Rising Sign Calculator

Estimate your rising sign from birth date and birth time. This quick astrology calculator uses a simple two-hour block method, not a full birth chart.

Scientific Calculator

Full scientific calculator with trig, log, exponents, factorial, memory, parentheses and DEG/RAD toggle. Runs in your browser.

Running Pace Calculator

Enter distance and finish time to calculate pace per km, pace per mile, average speed and projected 5K, 10K, half marathon and marathon finish times.

Pregnancy Due Date Calculator

Estimate your baby's due date from the first day of your last period or a known conception date. Uses Naegele's rule, cycle-length adjustment and standard obstetric timing.

Standard Deviation Calculator

Compute mean, variance, and standard deviation (sample n-1 or population n) for any dataset. Shows coefficient of variation and z-scores.