Free tool

Website Migration Risk Calculator

Score your migration out of 100 before you agree a launch date, and see which three variables are driving the risk.

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What it outputs

Risk score

A single number from 0 to 100

Status

Green, amber or red verdict

Top three risks

The variables driving your score

Traffic loss band

Typical loss for this migration type

What this tool does

Triage a Migration Before the Launch Date Is Set

This calculator converts a migration plan into a single risk score out of 100, then names the three variables contributing most to it. It is the same pre-launch scoring we run on every Visionary migration, and it exists because most migration disasters are governance failures rather than technical mysteries.

It takes seven inputs: migration type, the percentage of URLs changing, one to one redirect coverage, schema parity, content parity, whether a pre-launch test environment exists, and the launch timeline. It returns the score, a green, amber or red verdict, your top three risk drivers, and the typical short-term traffic loss band for that migration type drawn from our client portfolio.

It is built for in-house marketing leads and development teams who have a replatform, CMS swap, rebrand or redesign in the pipeline and need an honest read before committing to a date. The full method, phased rollout model and 47 point checklist sit on our SEO migration page, alongside the technical SEO work that follows a launch.

The calculator

Score Your Migration Out of 100

Migration type
Pre-launch test environment
Launch timeline

Risk score

55/100

Amber

Amber - close the top-3 gaps before launch.

Top-3 highest-risk variables

  1. 01Migration type: CMS swap
  2. 02URL changes (60%)
  3. 03Redirect coverage gap (20%)

Estimated traffic-loss band

5-15%

Typical for CMS swap given inputs

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How to use the results

Four Checks on the Score

01

Read the score against the three thresholds

Below 25 is a green light, and you can proceed with the plan you have. Between 25 and 65 is amber, which means close the top three gaps before you launch rather than after. Above 65 is red: a single day cutover at that score is how sites lose a third of their organic traffic, so the plan needs rebuilding before a date is agreed.

02

Fix redirect coverage first, because it is weighted hardest

Redirect coverage carries the heaviest weight in the score, and rightly so. A gap here means live URLs with equity pointing at 404s on launch day. Getting to a genuine one to one map for every indexed URL, validated for chains, moves the score further than any other single action.

03

Use the top three list as your pre-launch backlog

The three variables listed are ranked by contribution to your score, so work them in that order. Change one input at a time and rerun. If a change barely moves the number, it was not the constraint, and you have just saved your development team a sprint.

04

Buy down risk with timeline before you buy it with scope

Moving from a single day cutover to a phased four week rollout, and adding a full pre-launch test environment, together remove up to thirty points. That is usually cheaper and faster than cutting features from the new build, so try the timeline levers before you start negotiating scope away.

Worked example

A CMS Swap That Started Red and Launched Green

A CMS swap with 60% of URLs changing, 80% redirect coverage, partial schema parity and a single day cutover scores in the red band. Lifting redirect coverage to 100%, closing schema parity, adding a full test environment and moving to a phased four week rollout drops the same migration into the green band without changing a single feature of the new build.Same build, same team, thirty fewer risk points.

Redirect coverage

80% to 100%

Launch model

Cutover to phased

Verdict

Red to green

FAQ

Website Migration Risk Questions

It starts from a base risk for the migration type, then adds weighted penalties for URL change percentage, redirect coverage gaps, schema parity gaps and content parity gaps. It subtracts credit for a pre-launch test environment and for a phased launch timeline. The result is clamped to a 0 to 100 range.

Below 25 out of 100 is a green light to proceed. Between 25 and 65 is amber, so close the top three gaps first. Above 65 is a hold-and-rebuild, and a single-day cutover is not safe at that score.

It depends on the type. An HTTPS-only swap typically loses 1 to 3%, a CMS swap on the same domain 5 to 15%, a full replatform 10 to 30%, a domain swap 15 to 40%, and a redesign that preserves URLs 0 to 5%. Losing more than the top of your band means something went wrong rather than something normal.

No. A low score means the known structural risks are controlled, which is most of the battle, but it cannot see your specific templates, your server configuration or your internal linking. Treat the score as a pre-launch triage tool and pair it with a full crawl of the test environment before any change goes live.

Next step

Get a Real Migration Plan

Send us the migration you are planning and we will crawl the test environment, build the redirect map and give you a phased launch plan with the risks scored properly.

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Tell us about your business and we'll show you exactly where the opportunities are - no obligation, no sales pitch.

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■ Free audit included

📞 0191 607 6707✉ chris@visionary-marketing.co.uk