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Redirect Impact Calculator

Estimate the traffic and ranking impact of a site migration’s redirects.

About Redirect Impact Calculator

Migrations almost always cause a temporary dip that recovers over one to three months. Permanent loss comes only from URLs that were never mapped, which is why a complete redirect map matters more than anything else. The cumulative loss during recovery is usually the acceptable cost; unmapped URLs are the avoidable one.

Formula

Redirect Impact

Permanent loss ≈ traffic × unmapped URL share; cumulative loss integrates the recovery curve

temporary loss
Dip while search engines reprocess the new URLs
permanent loss
Traffic to URLs that were never correctly redirected

Worked example

With the default values below, Redirect Impact Calculator returns Traffic During Migration of 40,800. Change any input above and every figure here is recalculated in your browser.

Inputs used

Current monthly organic trafficminimum 0
48,000
Share of URLs redirected correctlyaccepts 0–100 %
92 %
Expected temporary traffic lossaccepts 0–100 %
15 %
Expected recovery periodaccepts 1–52 weeks
8 weeks

Results

Traffic During Migration
40,800
Estimated Permanent Loss
3,072
Cumulative Traffic Lost During Recovery
6,628
Monthly Traffic Lost at the Trough
7,200
Verdict
Too many URLs unmapped — expect lasting traffic loss

Step by step

  1. 1Values used
  2. 2Redirect Impact
  3. 3Traffic During Migration= 40,800
  4. 4Estimated Permanent Loss= 3,072
  5. 5Cumulative Traffic Lost During Recovery= 6,628
  6. 6Monthly Traffic Lost at the Trough= 7,200
  7. 7Verdict= Too many URLs unmapped — expect lasting traffic loss

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Redirect Impact calculated?

Permanent loss ≈ traffic × unmapped URL share; cumulative loss integrates the recovery curve Migrations almost always cause a temporary dip that recovers over one to three months. Permanent loss comes only from URLs that were never mapped, which is why a complete redirect map matters more than anything else.

Why does Redirect Impact matter?

The cumulative loss during recovery is usually the acceptable cost; unmapped URLs are the avoidable one.

What values do I need to enter?

This calculator takes 4 inputs: Current monthly organic traffic, Share of URLs redirected correctly, Expected temporary traffic loss, Expected recovery period. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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