Tool
Enter backlog, arrivals, and capacity
Core formulas: Finished per day = passes × (1 − rework); Days to clear = backlog / (finished − arrivals); Wait = backlog / finished
Calculator Library / Public Service
Service Backlog and Cycle-Time Analyzer
Find out how long a service backlog will really take to clear and how long a new case waits, and see how much cutting rework or adding capacity would change it.
Burn-down
Backlog over time: now versus target rework
Scenarios
What each change does
| Scenario | Rework | Passes / day | Finished / day | Net / day | Days to clear | Wait for a new case (days) |
|---|
Instructions
How to use this app
- Count the cases currently waiting, and the average number arriving each day over a representative period.
- Enter how many case passes your team completes per day, including passes that end in a return for more information.
- Enter the share of passes that come back for correction or missing information.
- Set a target rework rate to see how much a better front end would change the time to clear the backlog.
- Check the scenarios table to compare cutting rework with adding capacity.
What This Backlog and Cycle-Time Analyzer Helps You Decide
This analyzer answers a question most service offices cannot: how long will it really take to clear our backlog, and how long does a new case wait? It combines the number of waiting cases, the arrival rate, and the team's capacity, and it adjusts capacity for rework, because a pass that sends a case back does not finish it.
Use it to compare options such as reducing rework, adding capacity, or both, and to explain to leaders why fixing the front end of a process can beat hiring.
Core Formulas
| Measure | Formula | Meaning |
|---|---|---|
| Cases finished per day | Passes per day × (1 − rework rate) | Only passes that do not return actually finish a case. |
| Net change per day | Finished per day − arrivals per day | Positive means the backlog shrinks. |
| Days to clear | Backlog / net change | Working days until the backlog reaches zero, if arrivals and capacity stay constant. |
| Wait for a new case | Backlog / finished per day | Little's Law: work in process divided by throughput. |
Worked Example: A Benefits Claims Office
The pre-loaded values show 1,200 waiting claims, 55 arriving per day, 80 passes per day, and 25% rework. Finished cases are 80 × 0.75 = 60 a day, so the net is 5 a day and the backlog takes 1,200 / 5 = 240 days to clear. A new claim waits about 1,200 / 60 = 20 days.
With rework cut to 12.5%, finished cases become 70 a day, the net is 15, and the backlog clears in 80 days. A 10% capacity increase without touching rework clears it in 1,200 / (66 − 55) = about 109 days, so halving rework beats adding 10% capacity in this example.
Assumptions and Limits
- Arrivals and capacity are treated as constant. Seasonal peaks, staff absence, and policy changes will move both, so re-run the analysis regularly.
- Each returned case is assumed to re-enter the process, taking capacity, and rework is measured per pass. Define "pass" and "rework" the same way each time.
- The wait for a new case is an average from Little's Law and assumes a stable process. Also look at the age of the oldest case.
- The tool ignores case complexity and priorities. Treat the results as a planning estimate and check them against real data.
Service Backlog and Cycle-Time Analyzer Frequently Asked Questions
How is the time to clear the backlog calculated?
The tool subtracts the arrival rate from the number of cases finished per day, after removing passes that return for rework, and divides the backlog by that net figure. If arrivals equal or exceed finished cases, the backlog never clears at the current rate.
What counts as rework?
Rework is any pass that sends a case back instead of finishing it, such as a request for missing information, a correction, or a re-review. Define it consistently and measure it as a share of case passes, not as a share of cases.
Does adding staff or cutting rework help more?
It depends on the numbers, and the scenarios table shows both. When rework is high, reducing it often frees more capacity than a modest increase in staff, and it improves the resident's experience as well. Adding staff to a process with high rework can simply add more rework.
Why does the wait for a new case differ from the days to clear?
The wait is the average time a case spends in the system while the backlog exists, from Little's Law. The days to clear is how long it takes to eliminate the backlog. A backlog can be stable and still cause long waits, because the wait depends on how large it is compared with the rate of finished cases.