Why does a VPN reduce throughput?

VPNs add encryption and extra header data to every packet (encapsulation), and encryption/decryption also adds processing time — both reduce the effective data throughput compared to an unencrypted connection.

What's a typical VPN overhead percentage?

It varies by protocol and configuration, but overhead in the 10-20% range is common for OpenVPN and similar protocols; WireGuard is often cited as having somewhat lower overhead.

VPN Overhead Calculator

Calculate your effective usable throughput after accounting for VPN protocol overhead, which reduces the raw available bandwidth due to additional encryption and encapsulation headers on every packet.

Inputs

Results

Effective Throughput: 88 Mbps
Throughput Lost to Overhead: 12 Mbps

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Formula

Effective Throughput = Raw Throughput × (1 − Overhead % / 100)

Learn How This Works

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