LOG10 Function (OpenOffice Calc)
The LOG10 function in OpenOffice Calc returns the base‑10 logarithm of a number. Learn syntax, domain rules, examples, and best practices.
Verification status: Consult the documentation, examples and any stated test scope below. How formula examples are checked
Availability and version history
- Introduced: Documented by Apache OpenOffice 4.1.16; original introduction not established.
- Availability: Supported in Apache OpenOffice 4.1.16, verified against its function registry. This identifies a supported release, not a final working version.
- Scope: Desktop Calc, using the English function name. Availability in other spreadsheet applications is separate.
- Checked: 2026-10-14 — function reference; versioned support. Documentation/source check; not a new native test. Existing example-specific test claims below retain their stated scope.
The LOG10 function in OpenOffice Calc returns the base‑10 logarithm of a number. This is the “common logarithm” used in engineering, scientific notation, decibels, and scaling transformations.
What the LOG10 Function Does
- Computes the logarithm of a number using base 10
- Only accepts positive numbers
- Useful for scientific notation, decibels, scaling, and data normalization
- Works across sheets
- Equivalent to
LOG(number; 10)
LOG10 is ideal when you need common logarithmic scaling.
Syntax
LOG10(number)
Arguments:
- number — A positive numeric value
Domain Rules
| Input | Valid? | Notes |
|---|---|---|
| number > 0 | ✔ | Required |
| number = 0 | ✘ | Undefined |
| number < 0 | ✘ | Undefined |
| text | Check | Conversion-dependent; use numeric input |
Mathematically:
[ \log_{10}(x) \text{ is defined only for } x > 0 ]
Basic Examples
Log base 10 of a number
=LOG10(100)
Result: 2
Log base 10 of 1
=LOG10(1)
Result: 0
Log base 10 using a cell reference
=LOG10(A1)
Equivalent LOG expression
=LOG(A1; 10)
Advanced Examples
Convert scientific notation to exponent
=LOG10(A1)
Example:
If A1 = 1,000,000 → result = 6
Decibel (dB) calculations
Power ratio:
=10 * LOG10(P2 / P1)
Amplitude ratio:
=20 * LOG10(A2 / A1)
Normalize data on a log scale
=LOG10(A1 + 1)
Reverse a LOG10 transformation
=POWER(10; A1)
LOG10 across sheets
=LOG10(Sheet1.A1)
Logarithmic regression components
=LOG10(Y1:Y10)
Confirm with Ctrl+Shift+Enter.
Convert between log bases
[ \log_b(x) = \frac{\log_{10}(x)}{\log_{10}(b)} ]
Calc:
=LOG10(A1) / LOG10(B1)
Common Errors and Fixes
The scalar callback requires fVal>0 and then applies log10. Zero or negative input produces the illegal-argument path. A physically empty reference reads as zero and consequently fails that domain check. LOG10 does not ignore error values or scan a range looking only for acceptable values. The base is fixed: a second base argument is not part of the function signature. Upstream overflow or underflow is distinct from the logarithm of an already valid finite positive input.
For scalar numeric functions the checked reader distinguishes genuine empty references, strings, numeric values and errors. It can parse some numeric text, including ordinary integer text, and reads a physically empty referenced cell as zero. Therefore neither “all text is ignored” nor “all blanks always produce an invalid-argument error” is a safe general rule. A formula error propagates; it is not silently removed. Use explicit numeric cells in the reproducible tests, and inspect data types before changing a domain check.
Formula parsing errors are separate from mathematical domain errors. Check the function spelling, parentheses and the semicolon separator used in these examples. Number formatting affects display; the separate Calc precision-as-shown setting can also affect numeric reads, so the reference calculations assume ordinary stored-value precision. Dates and times are stored numeric values, but that does not make applying this mathematical operation physically meaningful to every date serial.
Best Practices
- Use LOG10 for engineering, scientific notation, and decibel math
- Use LOG for custom bases
- Use LN for natural logs
- Validate inputs to avoid negative or zero values
- Convert imported text numbers to real numbers
- Use named ranges for cleaner formulas
Reproducible numeric controls
| Formula | Independent reference result |
|---|---|
=LOG10(100) |
2 |
=LOG10(1) |
0 |
=LOG10(0.01) |
-2 |
=LOG10(1000000) |
6 |
=ROUND(LOG10(2);10) |
0.3010299957 |
=LOG10(0) |
ERROR |
=LOG10(-10) |
ERROR |
These are independent mathematical/source controls, not new native application or GUI observations. ERROR denotes an invalid or non-finite source path without inventing an observed localized message. Decimal expectations use the shown rounding precision; full stored results should be retained for subsequent arithmetic.
Complete worksheet and changed-input checks
Enter positive scales 0.01,0.1,1,10,1000 in A2:A6. In B2 enter =LOG10(A2) and fill down. The mathematical results are -2,-1,0,1,3. In C2 enter =POWER(10;B2) and fill down; these reconstruct the input scales mathematically. Each tenfold multiplication adds one to the logarithm.
A value that is not a power of ten does not have an integer logarithm. For A8=250, LOG10(A8) is approximately 2.3979400087. It lies between 2 and 3 because 250 lies between 100 and 1000; the logarithm is not a digit-count operation.
Advanced validation and model boundaries
Apply a defined ratio convention. For positive power ratio P2/P1=100, 10LOG10(100)=20 dB. For an amplitude ratio of 10 under a convention where power is proportional to squared amplitude, 20LOG10(10)=20 dB. The factor of 20 depends on that physical relationship and comparable conditions; the spreadsheet cannot establish it.
Check scientific notation. For 250=2.5*10^2, LOG10(250)=LOG10(2.5)+2. The original million example is the special case of mantissa 1. Preserve the mantissa when reconstructing a general value from its order of magnitude.
Treat shifted transforms as a model choice. LOG10(x+1) requires x>-1; it maps x=0 to zero. It is not the same as LOG10(x), and adding one changes the interpretation and units of a measured quantity. State why that shift is meaningful rather than using it only to hide zero-input errors.
Documentation and verification scope
The original useful examples, named-variable illustrations, shortcodes and design are retained; variables such as Radius, Rate, sd or Time must be defined as cells/names with the required units before those templates are executable. The earlier cross-sheet and Ctrl+Shift+Enter examples describe formula patterns, not a new GUI or array-entry test. Compatibility metadata does not certify identical coercion or boundary behavior in other products.
See the official LOG10 reference, 4.1.16 mathematics help, scalar elementary functions, SIGN and logarithm callbacks, POWER implementation, numeric argument reading, and non-finite result handling. The first help/core snapshots retain October 13 retrieval dates; POWER retains October 14. Numeric-reader and result-handler sources were retrieved October 15. Original introduction and final functioning version remain unknown; the supported 4.1.16 evidence above is separate.