which model to determine the magnetic declination is more accurate WMM (2014-2019) or IGRF (1590-2019)? I just wanted to determine the magnetic declination for calibration TruPulse Laser Rangefinder. I did not know which model would give me greater precision measurements (Azimuth+Distance)+(GPS+GIS)
Essentially, it doesn't matter.
The IGRF and WMM are both estimated from the most recent data and are of comparable quality.
It does state that WMM is a 'predictive model only', and IGRF is 'retrospectively updated' which I take to mean IGRF allows for historic use (showing what it was) whereas WMM is only valid for the period of the model. Since you're looking for a current setting, either will serve. I note the sample I put in on their calculator is the same or within margin of error for both. WMM returns 8 degrees 39 minutes plus or minus 21 minutes, while IGRF returns 8 degrees 40 minutes (no plus or minus). Both say it moves west at 6 minutes per year.