This basic calculator was built specifically for people training to lift the Dinnie Stones using rings with weight-loadable pins. It calculates the weight for each pin using the weight ratio of the original Dinnie Stones.
The total weight of the Dinnie Stones is 332.49kg. The large stone is 188.02kg, and the smaller stone is 144.47kg - a ratio of about 1:0.7684. This calculator rounds to 2 decimal places.
There are a few alternative calculation methods that might be useful to know if you need to figure out the weights to use, but don't have access to this calculator.
Firstly, you can calculate the small weight as 75% of the large weight. For example: 75% of a 160kg large weight would be 120kg.
With a 188kg large weight, the small weight will be 141kg instead of 144.5kg. Only a 3.5kg difference using the simple 75% method.
Depending on the plates you have access to, you can also use an easier 75% rule trick: For every 20kg (or 45lbs) plate you use on the large pin, add a 15kg (35lbs) plate to the small pin. Space on the pin can be an issue however.
Another common method is to use 'the 40kg gap' where you simply keep 40kg (or 90lbs) between the large weight and the small weight.
The 40kg gap is easy to remember and calculate. But the downside is that it is less accurate at lower weights. Using the calculator, 180kg would be 101.79kg and 78.21kg - a difference of ~23kg. Using the 40kg gap you would use 110kg and 70kg which is a much larger imbalance.