When to use this calculator
Estimate posts for a straight open fence run with equal maximum spacing. Includes two end posts for an open run; gates and corners can need additional posts.
Explore the slopes, layouts & dimensions calculators for other questions in this topic. For a related calculation, use the Ramp Length Calculator: Calculate inclined ramp length from vertical rise and horizontal run.
PUTTING IT INTO PRACTICE
Fence Post: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Fence length (m) | 30 |
| Maximum spacing (m) | 2.4 |
| Result | 14 posts |
- Check the input labels and enter the example values above.
- Apply the relationship: Posts = ceiling(length ÷ maximum spacing) + 1.
- The result is 14 posts, rounded for display.
How to interpret your result
Includes two end posts for an open run; gates and corners can need additional posts.
Use horizontal run for a slope calculation and perpendicular rise for height. A slope percentage is not an angle in degrees. These geometric tools do not establish compliance with local design or building requirements.
Frequently asked questions
Is a 10% slope the same as a 10° angle?
No. A 10% slope has a rise/run ratio of 0.10. Its angle is the arctangent of that ratio.
How do I use the fence post calculator?
Enter fence length (m), maximum spacing (m). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Posts = ceiling(length ÷ maximum spacing) + 1.
What should I check before using the result?
Includes two end posts for an open run; gates and corners can need additional posts.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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