Permeable Paver Runoff Calculator

Estimate runoff reduction using permeable paver area and rainfall.

sq ft
in
in/hr
hrs
%

Quick Facts

Pavers
Permeable
Permeable pavers reduce runoff
Infiltration
Rate
Rate drives capacity
Coefficient
Runoff
Runoff coefficient sets baseline
Decision Metric
Reduction
Reduction percent

Your Results

Calculated
Runoff Volume
-
Total runoff
Infiltration Capacity
-
Capacity per event
Reduction Percent
-
Runoff reduction
Overflow Risk
-
Overflow percent

Paver Plan

Your defaults show strong runoff reduction.

What This Calculator Measures

Estimate runoff reduction using permeable paver area, rainfall, and infiltration rate.

By combining practical inputs into a structured model, this calculator helps you move from vague estimation to clear planning actions you can execute consistently.

This calculator estimates runoff reduction with permeable pavers.

How to Use This Well

  1. Enter paver area and rainfall.
  2. Add infiltration rate and drain hours.
  3. Set runoff coefficient and overflow percent.
  4. Review runoff reduction.
  5. Adjust area or drainage.

Formula Breakdown

Runoff = area x rainfall x 0.623 x coeff
Capacity: area x rate x hours x 0.623.
Reduction: min(capacity, runoff) / runoff.
Overflow: runoff - capacity.

Worked Example

  • 450 sq ft at 1 in rain = 252 gal runoff.
  • Capacity about 117 gal.
  • Reduction around 46%.

Interpretation Guide

RangeMeaningAction
70%+High.Great reduction.
40-70%Good.Solid impact.
20-40%Moderate.Increase area.
Below 20%Low.Consider upgrades.

Optimization Playbook

  • Increase area: improve reduction.
  • Improve base: increase infiltration rate.
  • Reduce runoff coeff: use more permeable surfaces.
  • Plan overflow: direct overflow safely.

Scenario Planning

  • Baseline: current paver area.
  • More area: add 100 sq ft.
  • Higher rain: add 0.5 in.
  • Decision rule: keep reduction above 40%.

Common Mistakes to Avoid

  • Ignoring runoff coefficient.
  • Overestimating infiltration rate.
  • Skipping drain hours.
  • Not planning overflow.

Implementation Checklist

  1. Measure paver area.
  2. Estimate rainfall events.
  3. Test infiltration.
  4. Review reduction.

Measurement Notes

Treat this calculator as a directional planning instrument. Output quality improves when your inputs are anchored to recent real data instead of one-off assumptions.

Run multiple scenarios, document what changed, and keep the decision tied to trends, not a single result snapshot.

FAQ

What is runoff coefficient?

It represents how much rain becomes runoff.

How do I estimate infiltration?

Use soil tests or local guidance.

Should I include overflow?

Yes, overflow planning protects drainage.

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