Field Boost is a configurable BM25F weight that makes a term match in one page zone — such as the title or headings — count for more (or less) than the same match appearing in body text.
| Term | Field Boost |
|---|---|
| Category | Statistics and Evidence |
| Also known as | BM25F Boost |
| Where it appears | Settings → Factors |
What it means in RankGear
BM25F scores a page as a set of weighted fields — title, headings, body copy, anchor text — rather than one flat bag of words. Field Boost is the multiplier RankGear applies to a given field before those fields are combined into a single relevance score. You set it under Settings → Factors, where it controls how much a keyword match in a structurally prominent zone, like the page title, is worth relative to the same match buried deep in body text.
How to interpret it
Read Field Boost as a lever you control, not a measurement RankGear reports back. A boost above 1 amplifies that field’s contribution to the score; a boost of 1 is neutral; a boost below 1 dampens it. Because BM25F saturates term frequency, the effect is not linear — doubling a field’s boost does not double its influence, and a heavily boosted short field can outweigh a long one once length normalization is applied. Change one field at a time and re-run so you can see which weighting actually tracks the pages you are studying.
| Boost value | What it does to that field |
|---|---|
| Greater than 1 | Amplifies — matches in this field count for more |
| Exactly 1 | Neutral — the field contributes at its default weight |
| Between 0 and 1 | Dampens — matches here count for less |
Example
Say you are analyzing pages for “commercial roofing.” Competitors put the phrase once in the title, while your draft repeats it a dozen times in body copy. Raising the title Field Boost to 2.0 tells RankGear’s BM25F model to treat a single title match as worth roughly two body matches, so pages that place the term where it is structurally prominent score higher than pages that simply repeat it — helping you see whether prominence or raw frequency better explains the leaders in that SERP.
Important considerations
- Field Boost is a configuration input, not a measured metric — adjusting it changes how RankGear weighs on-page evidence, not the page itself.
- BM25F saturates term frequency, so higher boosts have diminishing returns and do not scale linearly.
- Boosts interact with length normalization; a boosted short field can dominate the combined score, so tune the two together.
- BM25F is a comparative relevance model, not a Google ranking signal. A higher field boost tells you how RankGear weighs evidence across zones — it does not mean emphasizing a field “makes pages rank.” Association with top-ranking pages is not causation, and small SERP samples can be unstable.
Related terms
Part of the RankGear glossary · how RankGear measures · the 870 factors.