How many 1st class stamps to use on heavy letters?

In our office, we buy Royal Mail stamps in ready to use denominations of “1st Class”, “2nd Class”, “Large 1st Class” and “Large 2nd Class”. However, these are only useful for 100g weight letters.

For heavy letters, we can use multiples of these stamps. I noticed I was routinely having to do the calculation in my head as to what is the optimum combination of stamps. For example, what to stick on a 500g 2nd class large letter. I know that’s £1.58, I know the stamps represent the 100g values, so 1st=65p 2nd=56p Large_1st=98p and Large_2nd=76p.

It’s not too hard to work out, but it takes time and gets harder with bigger letters and parcels.

For a coding challenge, I wrote “Stampulator“. It’s a single web page that tells us which combinations of stamps to use, so for the 500g 2nd Class large letter, £1.58 example, we need 1 x 1st class and 1x Large 1st class. That’s over by 5p, but it’s the nearest value to the cost.

I also made it so that if I have different value stamps or a different target value to reach (say; special offer or I’ve been slow to update the values when Royal Mail prices change) I can input those and get an instant result.

I then printed the page and stuck it buy our post box.  Stampulator is on my web server and free to use – it works well from a mobile phone too.

Post a comment here if it’s useful and that’ll encourage me to keep it up to date.

Google Chrome ” Failed – Network Error.” on downloading files greater than 5MB (ish) – solution for me = Disable QUIC

For the last few weeks I’ve had trouble downloading from Google Photos files. It only happened on large files; videos & zip files of multiple images. The problem only affected Chrome – the files would download fine using Firefox. For single images the download would work so I decided it must be something related to the files size. A lot of googling and it seemed to only affect me so I removed and fully reinstalled chrome, that didn’t fix it.

I found similar problems in the help forum but none of them had solutions (technically, one did by changing the download folder location but that didn’t work for me).

I used developer console to see what happened on the page and try and get more of an error message. I found “load resource: net::ERR_QUIC_PROTOCOL_ERROR”. I then googled that and found a page on stack overflow suggesting that disabling QUIC would help, and to disable it here: chrome://flags/#enable-quic

What is QUIC? It appears to be a protocol to improve performance of pages of the network using UDP. There were mentions that some networks/routers/devices don’t work properly with this format. I don’t know which part of the network between me and Google Photos is at fault, but once I disabled QUIC the downloads completed perfectly. If you want to know more, you’ll need to research it from here yourself. Sorry, I have work to do 🙂

Margins and Markups: how to handle multiple discounts/rebates

Following on from an old blog post about Margins and markups What everyone in business needs to know a reader posted this question in the comments

If you’re not sure how to calculate margins, read that first.

Hi, how do you do multiple rebates % to give a true value of what the total discount would be.
I.e. 3% + 6% + 8%, is this 17%

TL;DR … probably not 17% but it depends on how your supplier intended you to do it, more likely
100*0.97*0.94*0.92 = 83.8856 remaining, so
100 – ( 100*0.97*0.94*0.92 ) = 16.1144%

The answer is a blog post in it’s own right, but the short version is: It depends.

The most common use I’ve seen in my industry (UK businesses supplying other businesses with kitchen furniture and appliances) is to Apply each discount in turn, using the last result with the next discount value. The only way to be certain is to ask. Even then, you need to make sure you ask the right person. It seems to get confusing to sales reps and accounts departments alike. In once case, I only figured out by checking past supply invoices.

Simple example:
Supplier gives terms of:

  • 30% off retail price to all customers
  • 10% for displaying 1 product
  • 5% for displaying 3 products

This is typical of the ambiguous wording we see.

Note: I’m using the decimal form to calculate the margin – see how and why on the original blog post
In my own industry;
£100 * 0.3 = £30 discount, £70 cost.
The next 10% is 10% off the remaining COST, not 10% off the original retail price
£70 * 0.1 = £7 = £63 cost
The next 5% is in addition to the prior two discounts and also taken off the remaining Cost, not the original retail price
£63 * 0.05 = £3.15 = £59.85

Therefore, the margin for this supplier is: 40.15%
If you only have one location to put the margin, then use 40.15.

However…. it’s not always this simple, which is why you NEED TO CHECK YOUR SOURCE.

Here’s another example of what I’ve seen.
Supplier gives terms of:

  • 30% off retail price to all customers
  • 10% for displaying 1 product
  • 5% for displaying 3 products

This is typical of the ambiguous wording we see.
Wait, that’s the same example….. That’s right. But this time the supplier thinks it’s obvious everyone knows that the first 30% is given to everyone and that the extra for displaying 10% is 10% off the cost and that the extra extra 5% makes it 15% for displaying 3 products.

£100 * 0.3 = £30 discount, £70 cost.
The next 10% is 10% off the remaining COST, not 10% off the original retail price
£70 * 0.1 = £7
The next 5% is off the remaining cost before we got our earlier discount.
£70 * 0.05 = £3.50
Or, we could just say, 15% off the remaining cost in this case, £70 * 0.15 = £10.50
Total cost: £59.50
Margin: 40.50%

These small differences add up and can get confusing quickly.

Why isn’t there one system? It depends on why the extra margins are being applied and used. I’ve seen it deliberately used to make the discount appear bigger. A sales rep will incorrectly say: “We’ll give you 40% off for displaying this product, and if you display another product too we’ll give you an extra 20% off, that’s 60% discount!”…. no, it’s 100-(100*0.6*0.8)= 52% discount.