Logarithms Calculator with Steps

Solve logarithms, inverse forms, base changes, and equations step by step. Check domains and rules. Graph outputs, save work, and compare example results quickly.

Calculator

Example data table

Case Expression Result
Evaluate log_2(32) 5
Evaluate log_10(0.01) -2
Solve for x log_3(x) = 4 x = 81
Solve for base log_b(81) = 4 b = 3
Product rule log_2(8 × 4) log_2(8) + log_2(4) = 5
Quotient rule log_5(125 / 5) log_5(125) - log_5(5) = 2
Power rule log_10(100^2) 2 × log_10(100) = 4

Formula used

Change of base: log_b(x) = ln(x) / ln(b)
Inverse relation: If log_b(x) = y, then b^y = x
Product rule: log_b(MN) = log_b(M) + log_b(N)
Quotient rule: log_b(M / N) = log_b(M) - log_b(N)
Power rule: log_b(M^p) = p · log_b(M)

Domain rules: the base must be positive, the base cannot equal 1, and every logarithm input must stay greater than 0.

How to use this calculator

  1. Choose the calculation mode you need.
  2. Pick a base preset or enter a custom base.
  3. Enter the needed values for x, y, M, N, or p.
  4. Set decimal places and the graph range.
  5. Press Calculate to show the result above the form.
  6. Read the step list, review the graph, then export CSV or PDF.

FAQs

1. What does a logarithm mean?

A logarithm asks which exponent creates a number. In log_b(x) = y, the base b raised to y equals x. It reverses exponentiation.

2. Which bases are allowed?

A valid logarithm base must be greater than 0 and cannot equal 1. Negative bases and base 1 do not work in standard real logarithms.

3. Why must the input be positive?

Real logarithms are defined only for positive inputs. Zero and negative values fall outside the real-number domain for logarithmic evaluation.

4. When should I use natural or common logs?

Use natural logs for continuous growth and calculus work. Use common logs for powers of ten, scientific notation, and many school problems.

5. What is the change-of-base rule?

It converts any logarithm into a form using familiar logs. The rule is log_b(x) = ln(x) / ln(b), or the same idea with common logs.

6. Can this solve equations too?

Yes. It can evaluate a logarithm, solve for the input x, solve for the base, and expand expressions with product, quotient, or power rules.

7. Why is the graph useful?

The graph shows domain limits, slow growth, and where your solved point sits on the logarithmic curve. It also helps verify direction and scale.

8. What do the CSV and PDF downloads include?

The exports include the result summary and the step list. They are useful for assignments, revision notes, worksheets, and record keeping.

Related Calculators

Paver Sand Bedding Calculator (depth-based)Paver Edge Restraint Length & Cost CalculatorPaver Sealer Quantity & Cost CalculatorExcavation Hauling Loads Calculator (truck loads)Soil Disposal Fee CalculatorSite Leveling Cost CalculatorCompaction Passes Time & Cost CalculatorPlate Compactor Rental Cost CalculatorGravel Volume Calculator (yards/tons)Gravel Weight Calculator (by material type)

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.