Migration Parallel-Run Cost Calculator
See what paying for the old estate and the cloud at once costs, and the month savings start.
Each one fills in the fields below for a typical workload of that kind. You can change any of them.
The overlap
Optional
- Months both estates run
- 7
- Peak month
- $60,666.67
- Saving a month after
- $10,000.00
- Pays back
- Month 18
8 months from the first wave to the last decommission.
Month by month
- Month 1Old estate only$40,000.00
- Month 2Wave 1 cuts over$50,000.00
- Month 3$50,000.00
- Month 4Wave 2 cuts over$60,000.00
- Month 5$50,666.67
- Month 6Wave 3 cuts over$60,666.67
- Month 7$51,333.33
- Month 8$51,333.33
- Month 9Cloud only$30,000.00
The last row is the first month with the old estate gone. Download the CSV for the figures by estate.
What this means
- Pays back in month 18
After month 8 you pay $30,000.00 a month, $10,000.00 less than today. That repays the $94,000.00 the move cost above staying by month 18.
- Each month the old estate stays after cutover costs about $30,000.00
You keep each wave's servers for 2 months after it moves. A shorter rollback window, or notice given before cutover rather than after, brings the exit date forward by the same amount.
- Fixed costs run on for $48,000.00 after the first wave is gone
30% of today's bill (lease, power, support contracts, staff) does not shrink wave by wave. It ends with the last decommission, so the exit date is the number that moves it.
- Building each wave a month before cutover costs about $30,000.00
The environment is paid for while it is tested and idle. Worth it for a safe cutover; keep the window as short as the team can test in.
What this model assumes
Show
- Month 1 is the month the first wave starts, or the first month the cloud is built when the build lead is longer than the first wave’s slot. Waves are equal shares of the estate and cut over at even intervals along the timeline, each at the end of its month.
- The cloud is paid for from the build. Each wave’s share of the cloud bill starts the stated number of months before its cutover, at full size, and runs on after it.
- The old estate shrinks wave by wave, except its fixed share. Each wave’s share of today’s bill stops the stated number of months after its cutover; the fixed share stops when the last wave does.
- Payback counts savings against staying put, month by month, from month 1, until they cover the extra cost of the period and the one-time cost.
- Not counted: the transfer itself (the transfer cost comparator prices it), licenses that must be bought twice, hardware resale, and discounts that start later than the bill.
Planning the exit?
Cloud Cost Audit: We review the wave plan, the decommission dates and the target bill before the overlap starts, so the months of double running are the ones you planned. From $1,500, fixed. Nothing paid upfront.
Questions
What is parallel running in a cloud migration?
The months when the old estate and the new one are both paid for. Each wave's cloud environment is built and paid for before it cuts over, and its old servers are kept for a rollback window after. Lease, power and staff costs do not shrink wave by wave; they stop when the last wave is decommissioned.
How much does parallel running cost?
Add the old bill and the cloud bill for every month until the old estate is gone, then take off what staying put would have cost. A $40,000 a month estate moving to a $30,000 cloud bill in three waves over six months, built a month early and kept two months after, costs $94,000 more than staying over eight months.
When do cloud migration savings start?
Not at the first cutover. The monthly bill falls below today's only once enough of the old estate is switched off, and the overlap is repaid later still: in the example above the bill drops to $30,000 in month 9 and the move has paid for itself by month 18.
Why does the old bill not fall when the first servers leave?
Because part of it is fixed: the data center lease, the power contract, support agreements and the people who run it. Those costs end on the exit date, not when a rack empties, which is why the exit date moves the total more than the first cutover does.
How long should the old estate be kept after cutover?
As long as a rollback is realistic, and no longer. Every extra month costs that wave's share of today's bill. Give notice on contracts before cutover rather than after, and set a decommission date with an owner for each wave.
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OpenMore tools for: Compute and utilization
The overlap ends. The cloud bill does not.
Finitizer reads the new estate's bill from the first month, by workload, so the cloud figure in this plan is checked against what you are actually paying.
See how Finitizer works