Book movement calculator · Free tool
Calculate your book movement.
See how much of your book’s premium change came from customers arriving or leaving, and how much came from customers who stayed. Enter four annual in-force premium figures to build the bridge.
What changed in the Book?
Opening bookAnnual in-force premium at the first snapshot
−
Lost customersOpening premium that departed with customers
+
Gained customersClosing premium that arrived with customers
±
Change on retained customersDerived remainder across rate, exposure, coverage and mix
=
Closing bookAnnual in-force premium at the second snapshot
Fill in all four figures to build the bridge.
Read the result
Separate customer flow from retained-book change.
What changed overall?
Read the opening-to-closing change alongside customer arrivals and departures. A bigger book does not by itself show that the agency gained more customers.
opening − lost + gained + retained change = closing
Which customers arrived or left?
Classify by customer presence at the two dates. A policy rewrite or carrier remarket for a customer who stayed is neither a lost customer nor a gained customer.
customer present at only one endpoint
What changed on customers who stayed?
This calculator derives retained-customer change as the remainder from your four inputs. The arithmetic ties by construction; it does not independently verify the source records. More detail is needed to separate rate, exposure, coverage and mix.
closing − opening + lost − gained
Are we comparing like with like?
Use the same agency scope and annual in-force premium basis at both dates. Written premium, commission and other bases answer different questions and should not be mixed into this bridge.
annual premium at both endpoints
Before drawing a conclusion.
- Classify arrivals before calling them genuine new business. A gained customer may be an organic arrival, a reactivation or part of an acquired book.
- Investigate retained-book change before assigning a cause. The remainder combines rate, exposure, coverage changes and account mix.
- Check the reason with the agency. Customer presence at two dates shows what moved; it does not establish why a customer left or why the retained book changed.
Related questions
Asked alongside this one.
Did my insurance agency grow because of new customers or rate increases?
Compare lost and gained customer premium with the change on retained customers. If customer flow is flat or negative while retained-customer premium rises, existing accounts drove the increase. Standard Book snapshots still cannot separate carrier rate from exposure, coverage, and mix without additional evidence.
Read the note →How do you calculate movement in an insurance book of business?
Begin with annual in-force premium at the opening snapshot. Subtract the opening premium attached to customers who departed, add the closing premium attached to customers who arrived, and add or subtract the premium change on customers present at both dates. The result should equal closing annual in-force premium.
What is change on retained customers?
It is the difference between opening and closing premium for customers present at both snapshots. This combined figure can reflect rate, exposure, coverage, and mix. It should not be attributed entirely to employee sales activity or carrier pricing.
Does gained premium mean new business?
Not automatically. A customer absent at the opening snapshot and present at close is gained on a point-to-point book comparison, but the arrival could be organic new business, reactivation, or acquired business. Those classifications require additional evidence.
From a calculation to the management review
The bridge is easy. Building the inputs is the work.
See how Keelridge carries the same analysis into a recurring management review. Supported AMS Book reports become dated movement evidence after validation and confirmation, so management can investigate a change without assembling the picture again.