Read incremental savings, not headlines
A 55 percent three-year CUD sounds decisive until you subtract the 30 percent SUD you already get for free. The number that matters is the gap between those two lines on the same uptime assumption.
GCP · Free tool
GCP committed use savings calculator
Sustained use discounts are free. Committed use discounts are a bet on uptime. Put your monthly compute spend and average uptime in, and see on-demand, SUD, one-year CUD, and three-year CUD side by side.
Monthly cost comparison
| Option | Monthly cost | Savings | vs SUD |
|---|---|---|---|
| On-demand (no credits) | $0 | — | — |
| Sustained use only auto | $0 | $0 | — |
| 1-year committed use | $0 | $0 | $0 |
| 3-year committed use | $0 | $0 | $0 |
SUD rate: 0%
Frequently asked
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What is the difference between SUD and CUD?
Sustained use discounts apply automatically as instances run more hours in the month, capping around 30 percent. Committed use discounts require a one- or three-year spend pledge and push toward 37 to 57 percent depending on term and machine class.
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Should I buy a CUD if I already get SUD?
Compare incremental savings, not headline CUD percentage. If one-year CUD saves less than five percent beyond SUD at your actual uptime, fix rightsizing first. Three-year CUDs pay on stable baselines above 90 percent monthly uptime.
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Can I override the discount rates?
Yes. CUD percentages vary by region and machine family. Enter rates from your billing export or the GCP pricing calculator when precision matters.