VPN Bandwidth Calculator

Multiply the bandwidth one user needs by the number of concurrent users, then multiply by an overhead factor to account for VPN encapsulation and encryption. For example, 50 users each needing 2 Mbps with 10 percent overhead is 50 x 2 x 1.10 = 110 Mbps of aggregate throughput at the VPN gateway.

A VPN wraps each packet in an additional header and often encrypts the payload, which adds bytes that travel over the link without carrying user data. The exact percentage depends on the protocol (such as IPsec, WireGuard or OpenVPN), the cipher, and the packet size. Enter the figure your protocol documentation states; this calculator applies it as a multiplier.

Overhead varies widely with the protocol, encryption cipher, and average packet size, so there is no single correct number. Rather than hardcode an estimate, the calculator lets you enter the overhead percentage from your VPN software's own documentation, keeping the result accurate for your setup.

Sustained throughput in megabits per second multiplied by the seconds in a month gives megabits per month; divide by 8 for megabytes and by 8,000 for gigabytes. This calculator reports monthly gigabytes assuming the link runs at the calculated rate for the hours per day and days per month you enter.

Size to the realistic concurrent peak, not the theoretical maximum of every user at once, unless your application demands it. Estimate the highest number of users likely to be active at the same time and the bandwidth each genuinely needs. Over-provisioning wastes money; under-provisioning causes congestion at peak.