interactive · the three cfo numbers
The Mainframe Exit Calculator
Your run cost versus your exit cost, modeled in the open — three numbers and a seven-year curve, computed in your browser from assumptions you control.
client-side only · no data leaves this page · formulas below · july 2026
inputs
Every default is an assumption, not an observation. Overwrite each one with your own numbers.
the estate
the program
current annual run cost
—
fully loaded · year one
total exit cost
—
over the program
break-even
—
the month the exit turns cheaper
cumulative cost · 7 years
methodology · nothing up the sleeve
How the model works
Six formulas, written out. The chart plots the two cumulative lines month by month over 84 months.
+ hardware & facilities + (ftes × loaded cost per fte)
stay path, month m = software cost grown at the annual mips growth rate
(compounded monthly) + hardware and people held flat, ÷ 12
total exit cost = (program months ÷ 12) × (envelope % ÷ 100)
× current annual run cost
exit path, during the program = the stay-path month cost
+ total exit cost ÷ program months
(you keep paying full freight on the mainframe while you leave it)
exit path, after cutover = post-exit % × current annual run cost ÷ 12
break-even month = the first month the cumulative exit line
drops below the cumulative stay line
Assumptions the model makes
- nominal dollars — no inflation, no discounting, no NPV
- mips growth is applied to the software line only; hardware and people are held flat on the stay path
- program spend is spread evenly across the program months; real programs are lumpier
- savings start at cutover, in full, immediately; real ramps are slower
- post-exit run cost is held flat; growth on the target platform is not modeled
- the 7-year window is a chart choice, not a forecast horizon
This is a directional model, not a quote. PalmDigitalz publishes no pricing — the envelope default is your assumption to overwrite, not our rate card. Real numbers come from a scoped discovery of your actual estate, the inventory Palm Key produces — not from nine input boxes. When the direction looks interesting, scope a POC.
The model is the start of the argument, not the end.
Read the full cost anatomy behind the inputs, or take the procurement kit and put the hard questions to every vendor — including us.