# Left 4 Dead 2 How to Change Interpolation & Rates – Config Bind Guide

a quick config bind to change your interp and rates at the press of one button

# What is interp and why does it matter?

interp is short for interpolation, it is a mathematical term, all the explanations on the internet are too long. Basically interp calculates a medium value between your client and the server of where your character is and when you’re shooting. It affects how “direct” your shots and hitboxes feel. That’s all you need to know, for more math, check out wikipedia:

https://en.wikipedia.org/wiki/Interpolation – [wikipedia.org]

# Isn’t it “sort of” cheating to change it?

In Left 4 dead 2, servers use two different tick rates. Official valve servers have 30 ticks (per second) and some modded t1 servers have 100 ticks. On a 100 tick server, you’ll lag very badly with 0.1 (100ms) interp. It’s recommended and sometimes even required to change your interp and rates.

You could consider playing with 0 interp on a valve server cheating, but it is not bannable, however for your own convenience, and for the sake of fair play, I recommend against it.

Having a low interp on a valve server, especially 0, makes you lag aswell and does not yield the desired result. Other players will have more trouble hitting you, but you will also have more trouble hitting them. Many friends groups playing on valve servers will not tolerate people with 0 interp in their game.

# What to add to your config and where to find it

If it’s not there, you might wanna create or download it, or if it’s not working, edit the autoexec.cfg aswell. I have the bind in both of them just to be safe.

bind "o" "cl_interp_ratio 2; cl_interp 0.1; cl_updaterate 20; cl_cmdrate 30; rate 30000"
bind "p" "cl_interp_ratio -1; cl_interp 0.0; cl_updaterate 100; cl_cmdrate 100; rate 100000"


The order is important. Ratio 1st, interp 2nd.

P is for 100 tick modded servers, O is for valve servers.

You can replace o and p with any other buttons you like, I found it to be practical because you will rarely hit it by accident. Typing in chat will not trigger the changes.

I’m using net_graph 1 at all times so I can see what my interp is and how laggy the server is. Your interp will appear yellow if it’s the wrong one.

You could also do this, if you don’t want the numbers on your screen at all times:

bind "L" "net_graph 1"
bind "K" "net_graph 0"


# Q & A

Q: “Why is interp ratio -1?”

A: “I have no Idea, someone told me to do -1 rather than 0 and it’s better with -1”