Gera Ambulance Response Index — Methodology

A transparent, reproducible 0–100 score computed entirely from real NHS England AmbSYS figures. May 2026 edition.

How the index is computed

The Gera Ambulance Response Index is a single 0–100 score (identical in construction to the Gera Ambulance Performance Index) built from the two most safety-critical published mean response times. For each service we take the ratio of the Category 1 target (7 minutes / 420 seconds) to its published Category 1 mean, and the ratio of the Category 2 target (18 minutes / 1,080 seconds) to its published Category 2 mean. The score = 100 × (0.5 × C1 ratio + 0.5 × C2 ratio), capped at 100. A score of 100 means the service meets or beats both mean targets; a lower score means it is slower than target. Every input is a real, published NHS England AmbSYS figure.

Worked example: a service with a Category 1 mean of 6 minutes (360s) and a Category 2 mean of 18 minutes (1,080s) scores 100 × (0.5 × 420/360 + 0.5 × 1080/1080) = 100 × (0.583 + 0.5) = 100 (capped). England scores 75.3 / 100 for May 2026.

This is the same 0–100 construction as the Gera Ambulance Performance Index used across the per-service detail pages — the index page simply frames it as a named, monthly edition and adds the region roll-up below.

The region roll-up rule

NHS England reports AmbSYS per ambulance service, not per region. To score a region we pool its services’ published mean response times weighted by the number of incidents each handled — the mathematically correct pooled mean (pooled mean = Σ(mean × incidents) ÷ Σ incidents) — then apply the same 0–100 formula. We deliberately do not pool 90th-centile times, because weighting percentiles across services is statistically invalid; centiles are shown per service only.

Gera Ambulance Response Index by NHS England region (May 2026), fastest first
NHS region	Services	C1 mean (pooled)	C2 mean (pooled)	Index
1. North East and Yorkshire	2	7 minutes 22 seconds	22 minutes 5 seconds	88.3 / 100
2. North West	1	6 minutes 55 seconds	24 minutes 51 seconds	86.8 / 100
3. London	1	7 minutes	32 minutes 21 seconds	77.8 / 100
4. Midlands	2	8 minutes 17 seconds	27 minutes 56 seconds	74.5 / 100
5. East of England	1	8 minutes 17 seconds	29 minutes 47 seconds	72.5 / 100
6. South East	3	8 minutes 25 seconds	29 minutes 33 seconds	72 / 100
7. South West	1	9 minutes 22 seconds	40 minutes 24 seconds	59.6 / 100

Every service's Response Index (May 2026)

Gera Ambulance Response Index by service, fastest first
Ambulance service	Category 1 mean	Category 2 mean	Index
North East Ambulance Service NHS Foundation Trust	6 minutes 12 seconds	18 minutes 30 seconds	100 / 100
West Midlands Ambulance Service University NHS Foundation Trust	7 minutes 54 seconds	20 minutes 29 seconds	88.2 / 100
North West Ambulance Service NHS Trust	6 minutes 55 seconds	24 minutes 51 seconds	86.8 / 100
Yorkshire Ambulance Service NHS Trust	7 minutes 55 seconds	23 minutes 57 seconds	81.8 / 100
London Ambulance Service NHS Trust	7 minutes	32 minutes 21 seconds	77.8 / 100
South East Coast Ambulance Service NHS Foundation Trust	8 minutes 9 seconds	25 minutes 54 seconds	77.7 / 100
Isle of Wight NHS Trust	8 minutes 24 seconds	28 minutes 6 seconds	73.7 / 100
East of England Ambulance Service NHS Trust	8 minutes 17 seconds	29 minutes 47 seconds	72.5 / 100
South Central Ambulance Service NHS Foundation Trust	8 minutes 49 seconds	34 minutes 12 seconds	66 / 100
East Midlands Ambulance Service NHS Trust	8 minutes 47 seconds	36 minutes 27 seconds	64.5 / 100
South Western Ambulance Service NHS Foundation Trust	9 minutes 22 seconds	40 minutes 24 seconds	59.6 / 100

England ambulance response-time trend (12 months to May 2026)

England monthly mean and 90th-centile response times (NHS England AmbSYS, OGL v3.0)
Month	C1 mean	C1 90th	C2 mean	C2 90th	C3 mean	C4 90th
June 2025	7 minutes 55 seconds	14 minutes 5 seconds	29 minutes 34 seconds	60 minutes 11 seconds	104 minutes 54 seconds	317 minutes 38 seconds
July 2025	7 minutes 55 seconds	14 minutes 11 seconds	28 minutes 36 seconds	58 minutes 4 seconds	100 minutes 43 seconds	292 minutes 38 seconds
August 2025	7 minutes 47 seconds	13 minutes 55 seconds	26 minutes 59 seconds	54 minutes 40 seconds	92 minutes 47 seconds	274 minutes 57 seconds
September 2025	8 minutes 1 second	14 minutes 16 seconds	30 minutes 46 seconds	63 minutes 28 seconds	116 minutes 53 seconds	359 minutes 7 seconds
October 2025	8 minutes 1 second	14 minutes 18 seconds	32 minutes 37 seconds	67 minutes 19 seconds	124 minutes 15 seconds	372 minutes 33 seconds
November 2025	8 minutes 1 second	14 minutes 14 seconds	32 minutes 46 seconds	68 minutes 3 seconds	122 minutes 21 seconds	369 minutes 30 seconds
December 2025	7 minutes 59 seconds	14 minutes 14 seconds	32 minutes 43 seconds	68 minutes 48 seconds	121 minutes 18 seconds	348 minutes 57 seconds
January 2026	8 minutes 7 seconds	14 minutes 27 seconds	35 minutes 4 seconds	73 minutes 53 seconds	130 minutes 54 seconds	397 minutes 43 seconds
February 2026	7 minutes 50 seconds	13 minutes 59 seconds	28 minutes 57 seconds	59 minutes 29 seconds	102 minutes 24 seconds	326 minutes 52 seconds
March 2026	7 minutes 46 seconds	13 minutes 47 seconds	26 minutes 19 seconds	53 minutes 20 seconds	91 minutes 50 seconds	268 minutes 55 seconds
April 2026	7 minutes 40 seconds	13 minutes 43 seconds	24 minutes 27 seconds	49 minutes 4 seconds	83 minutes 59 seconds	253 minutes 23 seconds
May 2026	7 minutes 52 seconds	13 minutes 58 seconds	29 minutes 13 seconds	59 minutes 25 seconds	107 minutes 49 seconds	348 minutes 25 seconds

The Gera Ambulance Response Index is recomputed each month when NHS England publishes the next AmbSYS release. The re-date is a real data refresh, never a cosmetic bump.

Contains public sector information published by NHS England and licensed under the Open Government Licence v3.0.

Contains public sector information published by NHS England and licensed under the Open Government Licence v3.0. Source: NHS England — Ambulance Quality Indicators (AQI), AmbSYS (May 2026, published 11 June 2026).

Editorial data review: figures on this page are drawn directly from the official public source cited here and were cross-checked against that source at publication; derived values (percentages, medians, index scores) are computed from those published figures using the stated methodology — nothing is estimated or invented. Last reviewed: 3 July 2026. This page is general information, not medical advice.

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Informational/educational only — not a substitute for professional medical advice; a clinician interprets results.