Advertising pays for this site. There is no other revenue and no plan for one — no accounts to upsell, no premium tier, no data to sell. That makes the ad layout a design decision worth explaining, because the obvious layout and the right one are different.
The obvious layout puts an ad at the top of the page, where it is seen first and paid best. Every incumbent in this category does it, which is why using them feels like tunnelling through a billboard to reach a calculator.
The rule and the price
Our rule is simple: no ad above the tool, ever, and the tool usable without scrolling on a phone. Each page carries a fixed, small inventory — one small banner below the tool, one rectangle after the supporting content, and a tall unit beside it on desktop. Every slot reserves its exact height in advance, so nothing on the page moves when an ad arrives.
The rule costs money in the obvious way and earns it back in the less obvious one: pages that do not shift rank better, and visitors who are not ambushed come back. A site meant to outlast the incumbents can afford the patient version of this trade.