When I was still lingering in the corporate world, I was an accountant. So it never sit well with me when I learnt about the most common method crocheters/knitters are charging their commission.
You should have heard it or even use this formula yourself:
Cost of Materials × 3
While this is simple for everyone, there really is no correlation between how much your yarn cost and how much work you put in.
A more relatable way would be to charge the time put in. Some people charge how many hours they think they took or simply how many days/weeks they had spent.
As I may be a slow crocheter and I know that I wouldn’t sit through a full hour crocheting, I decided to be more precise. I timed myself for the different types of stitches and came out with a rate chart. I would work consistently on a full row or set of stitches and average the time out. I then multiple that rate with the number of stitches required.
If I had used the orthodox formula, I would have charged only $8.10 for a work with almost 4,000 stitches!
The same works the other way round if I had used really expensive or branded materials, it would result in a superfluous price.
Yarn & Parts
I keep an inventory spreadsheet listing all the prices, colour code and dye lot.
Even though we seek to get the best bargain we can, I suggest to charge based on the full or highest price you had paid for.
I personally would only do so if I see myself reordering the materials. For yarn bought specifically for a particular commission, I would charge as-is.
Keeping a list also help me see my usage and balance and also compare prices.
All these sounds like a lot of work, but they satisfy the accountability trait in me. You do you.
I’d created a Google sheet to show my formulas and example, you can save for your own use.