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Best Time to Book

San Francisco → London flights

SFO–LHR fares have a median of $315 across 30 daily snapshots, but a wide $226 spread means timing matters — aim to book when prices sit near the $307 p25 floor.

Target $307–$345 on SFO–LHR — the sweet spot in a volatile market

Key takeaways

  • Median fare is $315, based on 30 daily snapshots of the cheapest cached fares on this route.
  • The interquartile range is $307–$345 — half of all observed fares landed in this 12% band, making it a reliable target.
  • An $80 spread (low $281, high $507) signals meaningful price volatility — paying $507 would be roughly 60% above the median.
  • Bottom-quartile fares ($307 or below) do appear, so patience can pay off, though they're not guaranteed to recur.
  • No dominant carrier pattern was visible in the data, so comparing across airlines on each search is the most reliable strategy.

30-day price trend

SFO → LHR · cheapest cached fare per day · last 30 days · 22%
$269 low$432 high

See full numbers and stats on the SFOLHR price history page.

The full picture

San Francisco to London Heathrow is a competitive transatlantic route, and the 30-day fare snapshot reflects that complexity. The median sits at $315 — reasonable for a ~10-hour haul — but the spread is the real story here. At 80%, the gap between the floor ($281) and ceiling ($507) is wide enough that the timing and circumstances of your search can easily double your cost. The interquartile range of $307–$345 is the most actionable signal: fares in that band appeared in at least half of all snapshots, meaning they're not rare flukes. If you're seeing prices above $345, there's meaningful historical precedent for waiting or re-searching.

On booking-window dynamics, transatlantic routes generally see fare softening in two windows — roughly 6–8 weeks out, and again in the final 10–14 days when carriers push remaining inventory. However, the latter window carries real risk of seeing the $400–$507 range instead, particularly around peak travel periods. The data doesn't include departure-date metadata, so it's impossible to say definitively when in the booking horizon these low fares occurred. What is clear is that the $281 floor exists — it was captured at least once — so if your travel dates are flexible, monitoring fares for a week or two before committing is a reasonable approach.

No dominant carrier signal emerged from this dataset, which is consistent with how SFO–LHR works in practice: United, British Airways, Virgin Atlantic, and occasionally Lufthansa (via connections) all compete on this corridor, and the cheapest option shifts depending on the search date and departure window. Run searches across at least two or three aggregators rather than anchoring on a single airline's site. One honest caveat: 30 snapshots is a solid sample for directional guidance, but it covers only one rolling month. Seasonal demand — summer peaks, holiday surges — can push fares well above $507, a ceiling this dataset may not fully capture.

Ready to look at fares?

Search SFOLHR on Aviasales →See the price history →
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AI-authored from this route's 30-day price index. Article last regenerated Jun 13, 2026. Fares shift continuously — confirm at booking.

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