Calculate how VPN encryption affects your network bandwidth. Compare protocols like WireGuard, IPsec, OpenVPN, and L2TP/IPsec to find the best balance of security and performance for your needs.
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VPN encryption provides essential security but adds overhead that reduces effective bandwidth. Understanding protocol overhead helps you choose the right VPN solution and properly size your network infrastructure. This calculator shows exactly how much bandwidth different VPN protocols consume.
VPN protocols add extra bytes to each packet for encryption headers, authentication, and encapsulation. This overhead reduces the available payload space, effectively lowering your throughput. Modern protocols like WireGuard minimize this overhead with efficient cryptographic primitives, while older protocols like L2TP/IPsec add more overhead due to double encapsulation.
VPN Throughput Formula
Effective BW = Base BW × (Payload / (Payload + Overhead))Accurately size your network connection when deploying VPN for remote workers. Know exactly how much bandwidth you'll lose to encryption overhead.
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WireGuard is generally the fastest VPN protocol with only ~32 bytes of overhead per packet. It uses modern cryptographic primitives (ChaCha20, Poly1305) that are optimized for modern CPUs. In benchmarks, WireGuard often achieves near-gigabit speeds on capable hardware.
Typically 2-10% speed reduction for modern protocols like WireGuard or IKEv2, and 10-20% for OpenVPN. The actual impact depends on protocol choice, encryption strength, server distance, and your CPU's ability to handle encryption.
OpenVPN runs in user space rather than kernel space, adding CPU overhead. It also uses TLS for its control channel and has higher packet overhead. OpenVPN TCP mode is particularly slow due to TCP-over-TCP issues when encapsulating TCP traffic.
UDP is almost always preferred for VPN connections. It has lower overhead and avoids the TCP meltdown problem where TCP retransmissions inside the tunnel conflict with outer TCP. Use TCP only when UDP is blocked by firewalls.
VPN overhead reduces the effective MTU, potentially causing packet fragmentation. If packets exceed the path MTU, they must be fragmented, adding latency and overhead. Most VPNs auto-adjust MTU, but manual tuning (typically 1400-1420 for VPN) can improve performance.
Yes, WireGuard uses modern, audited cryptography (ChaCha20, Poly1305, Curve25519). Its small codebase (~4,000 lines vs. 100,000+ for OpenVPN) makes it easier to audit. All three protocols provide strong security when properly configured.