Compare metered and unlimited ExpressRoute circuits, find the break-even traffic volume and add the gateway cost.
An ExpressRoute circuit is billed as a fixed fee for the reserved bandwidth plus, on the metered plan, a per-GB charge for outbound traffic only — inbound is always free. Dividing the fixed-fee difference by the per-GB rate gives the volume at which the unlimited plan wins, which is why heavy-egress workloads like offsite backup almost always belong on unlimited. Two circuits at different sites, the ExpressRoute gateway in each VNet and the Premium add-on are all separate meters, so the circuit fee alone understates the real cost; the connectivity provider's own charge sits on top of everything Azure bills, so confirm both with the Azure pricing calculator and your carrier.
Azure ExpressRoute
break-even outbound GB = (unlimited fee − metered fee) ÷ metered per-GB price; monthly = circuit fee + premium add-on + metered outbound GB × price + gateway rate × 730.
break-even outbound GB = (unlimited fee − metered fee) ÷ metered per-GB price; monthly = circuit fee + premium add-on + metered outbound GB × price + gateway rate × 730. An ExpressRoute circuit is billed as a fixed fee for the reserved bandwidth plus, on the metered plan, a per-GB charge for outbound traffic only — inbound is always free. Dividing the fixed-fee difference by the per-GB rate gives the volume at which the unlimited plan wins, which is why heavy-egress workloads like offsite backup almost always belong on unlimited.
Two circuits at different sites, the ExpressRoute gateway in each VNet and the Premium add-on are all separate meters, so the circuit fee alone understates the real cost; the connectivity provider's own charge sits on top of everything Azure bills, so confirm both with the Azure pricing calculator and your carrier.
This calculator takes 9 inputs: Billing plan, Circuit bandwidth, Metered circuit fee, Unlimited circuit fee, Outbound data, Metered outbound price per GB, Premium add-on, ExpressRoute gateway rate, Billed hours per month. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.