Simply B

I wrote a Pocket PC utility to convert between WGS84 and OS formats and then show them on the map in TomTom or Ozi. This would do what you want, without the mental arithmetic. It's free to download from here: http://www.freenetpages.co.uk/hp/barrydavies/osgps.htm

A bold claim indeed - do you have documentary evidence to hush the outraged cries of the remaining 0.01% of computer users, who think they're better at it than you too? Sorry, couldn't resist it.

Wow, thanks for all the replies - and I'll take on board all the advice. And I'm reassured to see that my two (5 and 3) aren't the only little ones fascinated by anything dead.

Hi again "I was hoping for better than 100m accuracy" A 6 digit OS grid ref like this one only defines a point to the nearest 100m - you need 8 digits for 10m, or 10 digits for 1m. "I'm not sure how the additional 4 works either" The two letters define a 100kmx100km square within the national grid. SZ is the square that starts 400km (=400000m) east and 0km north of the grid origin. The 405 and 867 add the next 3 digits of accuracy to those starting values, so 400000m becomes 440500m and 000000m becomes 086700m. Taking your lat / long as input, my utility gives an OS grid ref, which should be good to within about 5m, of: SZ 40353 86796 which is indeed by a building on the nearby road. Hope this helps. The OS web site is a great source of information of this kind.

Hi there There's a mistake in your eastings figure - it should be 440500 for SZ 405 ... Putting that in InQuest gives ETRS89 of: N 50° 40.71282056' W 001° 25.68880185' and in my utility (which will be slightly less accurate) gives: N 50° 40.7134' W 001° 25.6894' and the Streetmap website gives the same as mine - see its map here All of these are very close to what your Garmin is telling you. Whenever I get conversions that are about 100m out, my first suspicion is a datum issue, for example entering a lat and long in what I think is WGS84 datum but is actually OSGB36, or vice versa. On my second cache hunt I did that, and my Pocket PC was telling me "it's another 20m that way" as I stood on the edge of a sheer drop. I went home and did some studying that night!

If you want to do it on a Pocket PC, my OS GPS Convertor utility converts either way and can then show the position on a map in TomTom Navigator or OziExplorer (from where it's easy to navigate to, create a waypoint, etc).

Greetings from four recent converts to geocaching. The kids and I love it, my wife considers it further proof that I am mad but will hopefully warm to it once the weather gets better. I've taken onboard advice about reaching double figures before starting to look at where to place my first cache. Eight being double figures, I've now spotted what I think would be a great site, and have been a few times to take positional readings without anyone noticing me. My only concern is that it is near (obviously not within) a rabbit warren, and while taking today's reading I nearly trod on the freshly half eaten remains of one, so presumably it's also a popular spot with foxes. So what is the general advice - is a tupperware box covered up on the ground (hey, I didn't claim to be original) either a risk to or at risk from the local wildlife? Best wishes Barry The B in BandMandAandA

You can search the PDF file - in the current Adobe Reader 7 there's a button with a pair of binoculars and the label "Search" that does it. In earlier versions it may have been called Find, if I remember right, but was definitely there if you "searched" for it!