=LOG10(number)

The directly retrieved official Zoho LOG10 function reference was checked on 2026-10-11. Its public article documents the function but does not provide a first-supported Zoho version or establish identical results across every historical web, mobile, Windows and macOS client. This guide does not assign an undocumented version number.

Download or import roots-logs-practice.csv from the review batch. Columns A–C contain a record ID, the input number and a descriptive label. Enter formulas into D. This shared dataset can be reused for SQRT, SQRTPI, EXP, LN and LOG10, but each function’s domain must be checked separately.

The expected values were calculated outside Zoho Sheet using Python’s math functions; they are not screenshots, copied Zoho results or a native engine validation. They are rounded mathematical expectations, so cell formatting may show fewer digits.

Step-by-step worksheet exercise

1. Import roots-logs-practice.csv beginning in A1. Use positive inputs in B2:B9 as the initial examples. The final two inputs intentionally test invalid domain values.
2. Enter Base-10 log in D1 and =LOG10(B2) in D2. Since B2 is 0.25, the independently calculated result is approximately -0.602059991.
3. Fill through D9. Check that B3=1 yields 0, B4=2 approximately 0.301029996, B6=10 exactly 1, and B8=100 exactly 2.
4. B9=0.001 gives -3. A negative result here is valid: it simply means the positive input is smaller than one.
5. Check Zoho’s official examples separately: LOG10(2) ≈ 0.301029996 and LOG10(0.3) ≈ -0.522878745. Their displayed precision is a reference, not evidence of identical formatting in every installation.
6. Do not include B10=-9 or B11=0 among the valid numerical expected outputs. Zoho specifically documents #NUM! for numbers less than or equal to zero.

Advanced: convert a power ratio to decibels

For a physical power ratio P2/P1 > 0, decibels are defined by 10×LOG10(P2/P1). If E2 contains 100 and F2 contains 1 in the same power unit:

=10*LOG10(E2/F2)

The result is 20 dB, because the power ratio is 100. If E2 is 1 and F2 is 100, the result is -20 dB. Negative decibels can represent a valid ratio below one; unlike a negative logarithm argument, a negative logarithm result is not an error.

The correct multiplier depends on what is being compared: for amplitude ratios under suitable equal-impedance assumptions, an expression using 20*LOG10(amplitude_ratio) is common. Do not use 10 and 20 interchangeably. A ratio of raw measurements can require calibration, baseline corrections or entirely different transformations.

LOG10 can also estimate decimal orders of magnitude. For a positive input of 12,500, =LOG10(12500) is approximately 4.096910013; the largest power of 10 not exceeding the number is 10⁴. =INT(LOG10(12500)) therefore gives 4 for that positive input. For values near exact powers of ten, numerical roundoff can affect integer-boundary decisions; test them before using this to generate scientific-notation bins.

• Domain: The official reference explicitly documents a #NUM! result for input ≤0. Guard the input upstream; an absolute value or arbitrary offset may conceal bad measurements.
• Small positives: Values such as 0.001 correctly return negative logs; the argument is positive even though the output is negative.
• Base: LOG10 always uses base 10. Zoho says this is equivalent to its LOG function with base 10, but the separate LOG help page was not fully retrievable in this run; avoid unverified details about LOG’s optional argument.
• Negative observations: If signs carry meaning, LOG10 cannot be applied directly in real arithmetic. Splitting sign and magnitude is a new model that must be justified explicitly.
• Rounding near powers: A decimal formatted as 1000 might be stored as 999.99999999999, so a computed log may be just below 3. Check raw values when classifying orders of magnitude.
• Text input: Scientific notation typed as text, thousands separators and locale-dependent decimals should be normalized, not assumed to coerce.
• Platform scope: The documented page does not give a complete historical release matrix or numeric-precision specification for every client.

Zoho’s function help pages list several common spreadsheet errors generically, including #N/A!; that is not proof that each error occurs for this specific arithmetic operation. Where the official function page gives a more specific domain error, the guide describes it above. For other domains, only a native Zoho test can confirm the exact engine response.

Microsoft’s Excel LOG10 reference documents the same one-argument, base-10 mathematical definition. It does not prove that Zoho reproduces all Excel text coercions or display/precision choices. The conceptual alternative =LN(B2)/LN(10) follows the logarithm change-of-base identity for positive inputs, but may differ slightly in the final floating-point digits. The separate Zoho LOG function may be a more direct alternative for arbitrary bases; its exact optional-argument syntax is not relied on here because its detailed page could not be freshly retrieved. Google Sheets execution was not tested.

• Zoho Sheet — function documentation

Verification status: Official documentation checked; example outcomes were independently reasoned or arithmetically checked where applicable. Not executed in Zoho Sheet.

• No genuine Zoho Sheet screenshots are included; this guide does not use mock application images.