About the Antilog Calculator
The antilogarithm, or antilog, undoes a logarithm. If the log of a number to base 10 is 2.5, the antilog of 2.5 is the number itself, 10 raised to the power 2.5, which is about 316.23. This calculator finds the antilog for the three most common bases, 10 for common logs, e for natural logs and 2 for binary logs, or for any positive base you type in. It also shows the logarithm of the answer so that you can see the round trip, and the exponent form. It is handy for chemistry (pH), sound levels, earthquake scales and any place where logarithms compress large ranges.
Updated October 2026
How to use the Antilog Calculator
- 1Enter the logarithm value x.
- 2Choose base 10, e, 2 or your own base.
- 3Read the antilog in the result box.
- 4Check the log of the answer in the table.
- 5Copy the result.
Examples
- Antilog base 10 of 2.5 is about 316.23.
- Antilog base e of 1 is e, about 2.71828.
- Antilog base 2 of 10 is 1,024.
- Antilog base 10 of −3 is 0.001.
- Antilog base 5 of 2 is 25.
Where antilogs appear
Decibels turn a ratio of powers into a log scale, and the antilog turns it back: 30 dB is a power ratio of 10 to the power 3, or 1,000. The Richter scale is logarithmic, so each whole step is ten times the shaking amplitude. Chemistry uses antilogs to move from pH to concentration, and finance uses them to turn continuously compounded rates into growth factors.
Be careful about the base when you read formulas. A scientific calculator's log key is base 10, while ln is base e, and some programming languages use log to mean the natural logarithm. If a formula says x = log y and you are not sure which base it means, check the surrounding context or a worked example. Using the wrong base gives an answer that is off by a constant factor, since changing base multiplies the log by a fixed number, about 2.3026 between base 10 and base e.
Using log tables
Before calculators, people used log tables and antilog tables. The whole part of a log gave the power of ten and the decimal part, the mantissa, was looked up in the antilog table to give the digits. The calculator does this directly with no table needed.
Related tools
The Log Calculator finds logarithms, the Exponent Calculator raises numbers to powers, the Scientific Notation Converter writes large numbers in powers of ten, the Decibel Calculator and the pH Calculator apply logs to sound and chemistry.
Features
- Base 10, base e, base 2 and custom bases
- Shows the check by taking the log back
- Large and small answers in exponent form
- Clear errors for invalid bases
- Handles negative and decimal inputs
- Free and instant
Frequently asked questions
What is the antilog of a number?
The antilog of x in base b is b raised to the power x. For base 10 and x = 3, the antilog is 1,000. It is the reverse of finding a logarithm.
How do I find the antilog on a calculator?
Use the 10^x key for base 10, the e^x key for natural logs, or the y^x key for other bases. Here, type x, choose a base and read the answer.
What is the antilog of 2?
In base 10 it is 100. In base e it is about 7.389. In base 2 it is 4. The base changes the answer, so always state which log you are undoing.
What is the antilog of a negative number?
A small positive number. The base 10 antilog of −2 is 0.01, and the antilog of −1 is 0.1. Antilogs of real numbers are always positive.
How is antilog used in pH?
pH is the negative base-10 log of hydrogen ion concentration. To go from pH back to concentration, take the antilog of −pH. A pH of 3 means a concentration of 10⁻³, or 0.001 moles per litre.
What is the difference between antilog and exponent?
Nothing in practice. Antilog is the older name for raising the base to a power. The word exponential is more common for natural logs, written e^x.