Prices, interest and costs
Index increase calculator
To work out an index-linked increase, divide the index value of the review month by the value of the base month and subtract one. Choose the index, enter both months and, optionally, the current amount, a cap and a floor. The calculator uses published values, applies the limits and shows the new amount step by step.
- Free to use
- Shows every step
- Embeddable on your site
General information, not legal advice. Check the result against your contract and the law that applies to it.
When to use it
Use it when a lease or supply contract ties the price to an inflation index and the review date comes up, or to check an increase a supplier has invoiced.
How to get a reliable answer
Step 1
Take the figures from the contract
Use the dates, periods and amounts the signed contract states, not a summary or an old spreadsheet.
Step 2
Check the working
Every result shows its steps, its assumptions and the data it used, so you can see where each number comes from.
Step 3
Keep it on the contract
In Pactinel the same calculation runs for every contract you hold and reminds the owner in time.
Frequently asked questions
Which month's index value should I use?
The one the clause names. Clauses often refer to a month before the review date, because index figures are published with a delay. Apply the same rule to the base month.
What do the cap and the floor do?
A cap limits how far the price can rise in one review and a floor how far it can fall. The calculator applies them to the index change before it works out the new amount.
Embed this calculator
Paste this code into your page. The calculator runs inside the frame and links back to this page.
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