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Choose a mainstream provider model, then use Advanced for exact regional or contract rates.
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{{ hours_per_month }} h
Use 730 for a planning month or reduce it for scheduled dev/test gateways.
TB and PB are decimal; TiB and PiB use 1,024-based factors.
Choose the substitute path used for traffic removed from NAT.
{{ offload_percent }}%
Estimate the endpoint/private-path share from flow logs, NAT metrics, billing exports, or service-destination shares.
{{ internet_percent }}%
Set lower when most remaining traffic stays on provider or private networks.
{{ cross_zone_percent }}%
Model the share of NAT-processed traffic crossing an availability-zone boundary.
Count only addresses attributable to this NAT design.
addresses
Enter zero to omit the budget-pressure comparison.
$/ month
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Changing a loaded profile rate switches the profile to Custom.
$/ unit-hour
USD per provider-billed GB or GiB-equivalent processed through NAT.
$/ GB
Effective USD per internet-bound GB after provider tiers and allowances.
$/ GB
USD per GB per charged direction.
$/ GB-direction
Count 0, 1, or 2 charged cross-zone directions according to the workload-to-NAT and NAT-to-destination path.
USD per attributable address-hour.
$/ address-hour
Used only for the endpoint substitute cost.
endpoints
USD per endpoint-hour.
$/ endpoint-hour
USD per offloaded GB.
$/ GB
Optional monthly appliance/operations cost used only in the optimization plan.
$/ month
Cost componentUsage basisMonthly costPlanning noteCopy
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ScenarioModeled changeMonthly totalImpactNext checkCopy
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Managed network address translation (NAT) gives private cloud workloads outbound connectivity without assigning each workload a public address. The network design is often simple to draw, but its bill is split across time, traffic, public IPv4 addresses, data transfer, and sometimes cross-zone or endpoint charges.

Traffic volume usually drives the largest cost changes. A gateway can incur a processing charge for every gigabyte that passes through it, while internet-bound bytes may also attract ordinary data-transfer charges. If a workload crosses an availability-zone boundary to reach the gateway, both network placement and the provider's charging direction can add another transfer component.

QuestionWhy it changes the estimate
How many billable NAT units run?Hourly charges may apply per gateway, active zone, or assigned VM, depending on the provider profile.
How much traffic remains NAT-bound?Private service paths and endpoints can remove eligible traffic from NAT processing, but paid endpoints have their own hourly and per-GB costs.
Where does traffic go?Internet egress and cross-zone transfer are separate from the NAT processing charge.
Are rates current?Region, offer, contract, tier, and provider price changes can make a preset differ from the invoice.

A cost comparison is meaningful only when every route uses the same traffic window and the same assumptions about egress. Endpoint offload is not automatically a saving, and a self-managed alternative is not complete unless its compute, operations, resilience, and remaining transfer costs are represented. Treat the result as a planning model and reconcile it against flow logs, billing exports, and the current regional rate card.

How to Use This Tool:

Map one billing month from observed traffic and the rate card that actually applies to the deployment.

  1. Choose the Pricing profile closest to the architecture. Set the billable gateway, active-zone, or assigned-VM count and the number of active hours.
  2. Enter monthly NAT-bound traffic and its unit. Estimate the shares removed through an endpoint or private path, sent to the internet, and hairpinned across zones from flow logs or billing data.
  3. Count public IPv4 addresses attributable to the NAT design. For a paid endpoint, enter its count, hourly rate, and processing rate; otherwise keep those charges at zero.
  4. Replace every loaded rate with the current regional or contract rate, then compare Monthly total, Effective cost per input GB, budget variance, and the optimization scenarios.

Interpreting Results:

Read the cost breakdown before acting on the total. A large processing line points to NAT-bound volume, a large internet line points to destination mix, and a large cross-zone line points to route placement. Endpoint cost must be compared with the NAT processing and transfer charges it replaces, not with zero.

Scenario differences are estimates under one changed assumption. No offload removes endpoint cost and sends all input traffic through NAT. No cross-zone sets the cross-zone share to zero. Schedule to 240 hours reduces active hours only when the current value exceeds 240. Add 15 points of offload caps the new share at 100%. Verify that each scenario is operationally possible before treating its difference as savings.

Technical Details:

The model converts the selected traffic quantity to gigabytes, removes the offloaded share, and applies each rate to the traffic or time base it bills. Percentages are independent planning inputs: internet-bound and cross-zone shares are both applied to the traffic that remains on NAT.

Formula Core:

Monthly cost is the sum of gateway time, NAT processing, internet egress, cross-zone transfer, public IPv4 time, and endpoint charges.

Go =Gp100 Gn =G-Go C =NHrh+Gnrp+Gne100re+Gnz100rzd+IHri+EHreh+Gorep

G is total input traffic in GB; p is offload percent; Go and Gn are offloaded and NAT-processed GB. N is billable NAT units, H is active hours, e is internet share, z is cross-zone share, d is charged cross-zone directions, I is public IPv4 count, and E is paid endpoint count. The r terms are the matching hourly or per-GB rates.

Lookup Core:

Built-in pricing profiles load the following planning rates. Values are USD per hour or per GB as shown and remain editable.

ProfileHourlyProcessing/GBInternet/GBCross-zone/GBIPv4/hour
AWS zonal or regional, US East$0.045$0.045$0.090$0.010$0.005
Google Public NAT, up to 32 VMs$0.0014 per VM$0.045$0.120$0$0.005
Google Public NAT, over 32 VMs$0.044 per gateway$0.045$0.120$0$0.005
Google Private NAT$0.045$0.045$0$0$0
Azure editable baseline$0.045$0.045$0.087$0$0.005
Input unitGB factorConvention
GB1Base unit
TB1,000Decimal
TiB1,024Binary
PB1,000,000Decimal
PiB1,048,576Binary

Annual cost is monthly cost multiplied by 12. Effective cost per input GB is monthly cost divided by total input GB, or zero when traffic is zero. Budget variance is budget minus monthly cost, so a negative value means the estimate exceeds the budget.

With the default AWS US East-style plan, 12 TB becomes 12,000 GB. A 25% offload leaves 9,000 GB on NAT; 70% internet share produces 6,300 egress GB and 20% cross-zone share produces 1,800 cross-zone GB. At the loaded rates, the components are $98.55 gateway time, $405 processing, $567 internet transfer, $36 cross-zone transfer, and $10.95 public IPv4, for $1,117.50 per month.

Accuracy and Pricing Notes:

Provider prices and billing definitions can change by region, date, currency, offer, tier, and contract. The built-in profiles are editable planning baselines reviewed on August 12, 2026; they are not live price feeds.

  • Confirm whether the provider bills decimal GB or binary GiB. The model labels its canonical traffic unit GB and converts TB/PB with decimal factors and TiB/PiB with 1,024-based factors.
  • Internet egress, cross-zone transfer, endpoints, logging, VPN, Interconnect, support, taxes, and discounts may follow separate rate cards.
  • The self-managed comparison adds the entered monthly self-managed amount to modeled internet, cross-zone, IPv4, and endpoint charges. It omits managed NAT hourly and processing charges, so the entered amount must cover the replacement's compute and operating cost.

References: