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Calculate the antilogarithm of any value using base e, 2, or 10. Instantly restore the original number
Calculation Formula:
x = antilog_b(y) = b^y
10^2
Exponential Function Curve y = b^x
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
An antilogarithm reverses a logarithm. If logb(x)=y, then x=by: raise the same base b to the known logarithm value y to recover x. For example, log10(100)=2, so the antilog of 2 in base 10 is 102=100. The base matters; a value of 2 gives 4 in base 2 and about 7.389 in base e.
Enter a logarithm value and any valid numeric base greater than zero and not equal to one. The main result uses the base you enter. Additional results show ey, 10y, and 2y for comparison. A logarithm value by itself does not determine one answer unless its base is known.
Reference: NIST Digital Library of Mathematical Functions, §4.2 — exponential and logarithm definitions and relationships; checked 2026-09-28.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Find the base used in the original logarithm. Use 10 for log10, 2 for log2, or the value e (about 2.71828) for a natural logarithm ln.
Type that base in the base field. Other bases also work if they are positive and not 1.
Enter the logarithm value y. Zero and negative values are valid inputs.
Read the main result by. Compare the listed base- e, base-10, and base-2 values if useful; these are reference calculations, not replacements for the selected base.
Adjust displayed decimal places if needed. The field accepts 0–15, with 0 using the default of six places.
Use cases
See how the tool fits into real work and everyday tasks.
For log2(x)=5, enter base 2 and value 5. The result is 25=32; substituting gives log2(32)=5.
If a worksheet or analysis records a quantity as a logarithm, use the same base to convert that value back to its exponential-scale number. Keep the original units and formula with the result.
With base 10 and y=−2, the result is 10−2=0.01, still positive. When the base is greater than 1, a negative exponent gives a value between 0 and 1. For a base between 0 and 1, the direction reverses: 0.5−1=2.
Q&A
Find concise answers to common questions and confusing cases.
No. It means raising the logarithm base to the input power, by; it is not 1/y.
Yes. For example, 10−1=0.1. The result remains positive for the valid positive bases used here.
The base is the number being raised to the exponent. For y=2, 22=4 while 102=100. Match the base from the original logarithm.
Notes
Review scope, result limitations, and important precautions before use.
The base must be numeric, greater than zero, and different from one. Very large or very small outputs may be shown in scientific notation; values beyond ordinary floating-point range can overflow or underflow. Decimal places change formatting, not calculation precision.
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