Apple’s bumper latest profits are being explained partly by the old saw that Macs are expensive. Old assumptions are worth kicking and this one is not true, at least for laptops: a Mac is up to 18% cheaper on a like-for-like comparison.

Let’s compare a business-spec Mac laptop with a Windows one. We’ll include Exchange support, as it’s the dominant e-mail and calendaring system of choice for most businesses, but also look at the cost for a Google Apps user.

My starting point is my own business laptop: a 13″ MacBook Pro. For comparison, the 13.3″ Dell Latitude E4300. I’m giving Windows the benefit here – Dells aren’t as well made as Macs but they’re good enough.

I chose the faster 2.53GHz processor for each, to get an exact match. To match the high specs of the MacBook Pro, I had to add many of the Dell’s optional extras (Dell specialise in low headline prices for barebones configurations): MS Office Small Business (£179), screen camera, 4GB RAM, 250GB 5200rpm hard drive, larger battery, backlit keyboard and Bluetooth. To match the Mac’s lack of antivirus, I downgraded Dell’s to a 30-day trial.

The warranty and support options are difficult to match. Dell includes a 3-year next business day warranty service that is sufficient if you also have an IT support company on hand – Dell’s telephone support is notoriously ‘offshore’. Apple includes only a 1-year warranty by default so you really need to pay another £170 for AppleCare – but you then get a very high quality telephone support service as well as a 3-year warranty. To keep things equal, I upgraded Dell’s support to ProSupport (+£112) to match the quality of AppleCare and added the latter to the Mac. To match Office, I added iWork (£47) to the Mac.

The prices for the key options are (excluding VAT, including delivery):

Exchange & Office apps, full support: £1486 (Dell E4300)/£1216 (Apple MacBook Pro)

Exchange & Office apps, 3-year warranty: £1374 (Dell E4300)/£1216 (Apple MacBook Pro)

Google Apps users, 3-year warranty: £1195 (Dell E4300)/£1169 (Apple MacBook Pro)

If you are an Exchange and Office user with an IT department, the Mac is £158 cheaper. If you need full telephone support, the Mac is £270 less – 18%. These gaps are partly because Macs now have Exchange support built in so you can use the much cheaper iWork for editing documents, whilst Windows users still have to buy MS Office to get Outlook.

However if you moved to Web-based services such as Google Apps and drop Office/iWork, the gap narrows to just £26 in favour of the Mac. But as a bonus, this Mac price also includes better telephone support and build quality (aluminium casing, etc).

Is that the end of Macs being more expensive than Windows? No – if you’re on a tight budget you can get a low-spec Windows laptop far cheaper than the most basic MacBook. But if you’re comparing like for like, a Mac laptop is cheaper.

The new MacBook (released Oct 20) has a better LED screen, more power, a 7-hour battery and the fabulous multi-touch trackpad. It’s still in a plastic body, but it looks more than suitable for a frugal business. The closest Dell Latitude to this is the E4300 with the 2.4GHz processor; although slightly more than this MacBook’s 2.26GHz, it’s near enough. The Dell, configured to match, costs £1103 (net); the MacBook with superior warranty and support costs £864 – more than 20% cheaper. If you need Exchange support, the gap could double.

Can this be right? I’ve had to add luxuries such as a camera, backlit keyboard, Bluetooth and larger battery to the Dell to match the typically well-spec’d Mac; removing these saves £94. The Mac is still much cheaper (and you get the incomparable multi-touch trackpad).