12 T speed and KM/Mile calculation

Hey,
I am new here, and i own my first WR for 2 weeks now :)
The previews owner change the frot sprocket to 12T.
I have noticed that the speed is shows in the Speedometer is not accurate, i dont have problems with that :), my question is if its impact the KMs/miles calculation ?

Thanks Nicolas

Yes, you can get a speedohealer or simular to correct it.

*Waiting for warnings regarding 12t front sprocket*

Thanks, Can you recommend for speedohealer ? (I mean if you have a link for buy that ship to IL)
Thanks

http://shop.12oclocklabs.com/index.php?route=product/product&product_id=59  (also see links at the bottom of this linked page for setup calculator, video, and user manual etc.)

Save a few bucks and get free shipping if you have Amazon Prime:
https://www.amazon.com/12-oClock-Labs-SDRD-Y1-Speedometer/dp/B00BI1U8VQ

Thanks :)

I have order 12 oClock Labs SpeedoDRD, and some one told me that it cant fix odometer and speed, and that I need to decide which one do I want to fix.
Can some one explain how do I decide?
And how to calculate it? (using KMs)

Thanks

Theres about 8% difference between odo and speedo, this will always exist.

You cab have the odo 4% low, and speedo 4%, getting pretty close.

Or choose which one is most important, and set that right, and have the other 8% out.