After a long time absent, I just tumbled on this thread. I think that some of the prices here are rather high.
Ceramics - starting at £18 psm. Bathroom last week, 4 walls and floor, 25sq m; one window recess, 3.5m of pipe boxing. Walls using 600x300 ceramics in brickbond, and floor 600x300 straightbond. Charged £450 labour (£18 psm) and completed in 3 days - i.e. £150/day.
Porcelain floor - usually about £20 psm. Last month completed 54 sq m floor in 4 days. Priced at £20 psm, £1056, which earns me £264/day.
Natural stone - very hit and miss, price structure usually starts at £30 psm, and rises to £60, depending on work required. In June I completed 26 sq m of 22mm thick tumbled limestone in grand opus pattern and 28 sq m of 400x600 limestone on bathroom walls. Priced at £25 psm for a builder who agreed to do all prep work and seal tiles after. Total £1350, 7 days in total, or about £190/day. However, last month I tiled 600x300 limestone tiles in an en suite bathroom on third floor of a terraced house in Bristol, with all tile cutting three floors down at rear, no skip, garden the size of the bathroom, which had 22 sq m of tiling required. It took me 7 days and was charged at £38psm or just £120 per day. That was an expensive error on my part but we all learn from our mistakes!
Materials. Usually priced per sq m when supplied - so rsf grey adhesive for porcelain floor with 5mm x 9mm grout gap - £8 psm. Stone tiling with rsf white adhesive, and 7x15mm grout gap would be £16 psm.
Day rate - Bath and Bristol £175/day (must include free parking), elsewhere £150. I class a lot of jobs up to 12 sq m as "tile in a day" jobs; i.e. in, set out, prime, fix and grout in one day - as long at tiles are fixed by 2pm, this is achievable. These are excellent jobs to fill in odd day gaps from larger commissions.
Discounts - Friends and family are charged less - not telling you by how much. Quiet periods bring lower prices to keep monthly costs paid. Larger tiling may attract price discounts, depending on what incentives I am given.
Windows/boxing-in/hole cutting. These are all standard problems for tilers - come on guys you cannot charge to drill a hole. I usually accept one window recess and up to a metre of boxing without increasing the price, but actually they are not that difficult, and the extra time taken is balanced by clean walls - a 6 sq m wall with no holes or obstructions should take me about 3 hours at the most, whilst a (metal) trimmed uneven window recess can take about the same amount of time.
Kitchen worktop splashbacks. A tricky one sometimes. I can expect to complete 4 sq m tiled, grouted and siliconed in a day, but sometimes there is a lot of fiddling around fittings, and differing socket heights and window recesses may require some lateral thinking on planning the height of the tiles. I always now charge this on a day rate. I have even tiled a curved wall with metro tiles in a brickbond pattern - again lateral thinking on running break lines like you have to in some wet room floors - customer thought it looked fantastic though.
Additional work: Ditra mat - I usually price to supply Ditra, adhesive and fix as a single price. It allows me to make a decent profit on obtaining Ditra at special prices whilst customers can rarely source the material below £12 psm. e.g. 44 sq m of Ditra supplied and fitted at £18 psm. Just like carpet and vinyl suppliers do! Levelling depends on depth, but again it makes sense to try to supply and fit at a psm price (but beware of any serious depth differences). To provide a 3-5mm level using a flexible self levelling compound I charge around £12 psm.
Competition - there are still guys in my area tiling for £80/day. I suspect some work on site Monday to Friday, but its very difficult in price conscious times to compete with that, so I don't try. Customer service alone makes my prices competitive. Timeliness, keeping promises, politeness, quality work, cleanliness, and accurate pricing seems to give me the edge. We all have off days too, but I try to keep a professional face on my work, and I try to give the customer the result they want - I have even removed and replaced natural stone tiles because the "pattern on the tile does not match the ones around it" - in fact on one floor I allowed the customer to direct where the (6 different) patterns of the porcelain tiles went just so that they were happy with the finished result (and yes some customers are that picky!)
The final word on pricing - I make a site visit on 95% of all jobs. I price according to what needs to be done, and site visits reduce pricing errors. Tiles sizes are only an issue when the surface to be tiled is an issue - if the surface is perfectly flat and sound, even small tiles can be applied quickly, although a 600x600 tile installation will always be quicker than a 100x100 tile. I am more likely to increase the price for facility issues - parking, access and loading, cutting area restrictions, height of tiling, waste, traffic jams (it takes me less time to travel to Swindon - 50 miles - than to Clifton in Bristol - 17 miles) than for tiling problems.