Bishop Score Calculator (Cervical Readiness for Induction)

Background.

The Bishop score describes how ready a cervix is for induction of labour, from five findings on vaginal examination: dilation, effacement, fetal station, cervical consistency and cervical position. It is a clinical aid for clinicians. It describes the cervix; it does not decide whether to induce, it does not choose a ripening agent, and it is not a diagnosis. The decision to induce rests on the clinical indication and on discussion with the woman, and the score is one input to how that induction is likely to go.

Dilation, effacement and station each contribute up to three points; consistency and position each contribute up to two. That is why the maximum is 13 and not 15, which is the first thing people get wrong about the score. The minimum is 0.

The most dangerous detail on this page is the station scale, and it is why the input is worded the way it is. Bishop's 1964 bands were written for the −3 to +3 station system: −3 scores 0, −2 scores 1, −1 or 0 scores 2, and +1 to +3 scores 3. Modern obstetric documentation almost universally uses the −5 to +5 scale, on which −4 and −5 exist and +3 is mid-descent rather than the floor. Those are different scales, and StatPearls states the difference explicitly. This calculator therefore asks for a station grade from 0 to 3 with Bishop's own descriptors printed on the field, and leaves the mapping from a −5 to +5 station to the clinician. It does not guess, because a guessed mapping would silently change the score by up to three points.

The interpretation bands are genuinely disputed, and this page reports that rather than hiding it. ACOG Practice Bulletin 107 describes an unfavourable cervix as generally defined as a Bishop score of 6 or less in most randomised trials, and says that above 8 the probability of vaginal delivery after induction is similar to spontaneous labour. Other widely used references treat everything up to and including 8 as unfavourable. The two agree at both extremes and disagree about 7 and 8, so this calculator reports three bands: unfavourable at 6 or less, intermediate at 7 to 8 with a note that sources differ, and favourable above 8. Reading the intermediate band is a clinical judgement, not an arithmetic one.

The published bands also have gaps, and this calculator fills them explicitly rather than silently. Effacement is printed as 0 to 30 percent, 40 to 50, 60 to 70 and 80 or more, which leaves 31 to 39, 51 to 59 and 71 to 79 unassigned. Dilation is printed as closed, 1 to 2 cm, 3 to 4 cm and 5 or more, which leaves fractional values unassigned. Here, effacement below 40 percent scores 0, below 60 scores 1, below 80 scores 2, and 80 or more scores 3; dilation below 1 cm scores 0, below 3 scores 1, below 5 scores 2, and 5 or more scores 3. Nothing is rounded before a comparison, so an effacement of 39 percent scores 0 and 40 percent scores 1.

The component breakdown is reported alongside the total for a practical reason. A Bishop score of 6 driven by a posterior, firm, undilated cervix at high station is a different clinical picture from a 6 in a woman who is already 4 cm dilated with the head at the spines but a posterior cervix. The total says how far from favourable; the components say why.

One last note on scope. This is a cervical examination — an intimate examination requiring consent and performed by a qualified clinician. The calculator cannot perform it, cannot verify it, and cannot tell whether the findings entered are the ones that were observed. Everything it produces is arithmetic on numbers somebody else supplied.

What is bishop score calculator?

The Bishop score is a five-component assessment of cervical readiness for induction of labour, published by Edward Bishop in Obstetrics and Gynecology in 1964. It grades cervical dilation, effacement and fetal station from 0 to 3, and cervical consistency and position from 0 to 2, for a total between 0 and 13.

Its purpose is prognostic rather than diagnostic: a favourable cervix predicts that an induction will proceed much like spontaneous labour, while an unfavourable one predicts a longer induction with a greater chance of it failing. That is why it is used to decide whether cervical ripening is likely to be worthwhile before induction proper begins.

The score has been modified in various ways over sixty years — simplified versions dropping consistency and position, and variants that adjust for parity — but the original five-component form remains the one most protocols specify and the one implemented here.

What it is not: an indication for induction, a prediction for an individual woman, a mode-of-delivery decision, or something that applies to a woman already in established labour.

How to use this calculator.

1. 01Use the score at term when induction of labour is being planned. It describes the cervix; the indication for induction is a separate question.
2. 02Enter the cervical dilation in centimetres and the effacement as a percentage. Both are compared against the band edges exactly as entered.
3. 03Enter the fetal station as a grade from 0 to 3 using Bishop's −3 to +3 descriptors: 0 for station −3, 1 for −2, 2 for −1 or 0, 3 for +1 to +3.
4. 04If your unit documents station on the −5 to +5 scale, map it yourself before entering it. The calculator deliberately does not guess a mapping.
5. 05Grade consistency as 0 firm, 1 medium or 2 soft, and position as 0 posterior, 1 mid or 2 anterior.
6. 06Read the component breakdown alongside the total, so you can see which component is limiting.
7. 07Treat a total of 7 or 8 as a judgement call: ACOG's framing and other references disagree about that range.
8. 08Do not read the score as a decision. Whether to induce, when, and with what, is a clinical decision made with the woman.

The formula.

The Bishop score is the sum of five graded components. Cervical dilation scores 0 when the cervix is closed, 1 at 1 to 2 cm, 2 at 3 to 4 cm, and 3 at 5 cm or more. Effacement scores 0 at 0 to 30 percent, 1 at 40 to 50 percent, 2 at 60 to 70 percent, and 3 at 80 percent or more. Fetal station scores 0 at −3, 1 at −2, 2 at −1 or 0, and 3 at +1 to +3, all on Bishop's −3 to +3 scale. Cervical consistency scores 0 firm, 1 medium, 2 soft. Cervical position scores 0 posterior, 1 mid, 2 anterior. The maximum is 3 + 3 + 3 + 2 + 2 = 13 and the minimum is 0.

Rounding stage: there is none. Dilation in centimetres and effacement as a percentage are compared against the band edges exactly as entered — an effacement of 39 percent grades 0 and 40 percent grades 1, and a dilation of 2.9 cm grades 1 while 3.0 grades 2. The three graded components are whole numbers, and the total is an exact integer sum.

The published bands leave gaps, which this calculator fills explicitly with strict upper bounds so that every possible measurement is assigned. Effacement below 40 percent grades 0, below 60 grades 1, below 80 grades 2, and 80 or more grades 3 — so the source's unassigned 31 to 39, 51 to 59 and 71 to 79 ranges fall into the band below. Dilation below 1 cm grades 0, below 3 grades 1, below 5 grades 2, and 5 or more grades 3.

The station component is entered as a grade rather than as a station, because the station scale changed under the score. Bishop's bands are on the −3 to +3 system, while modern documentation uses −5 to +5, on which stations of −4 and −5 exist and +3 is not the floor. Mapping between them is a clinical judgement about descent, and this calculator asks the clinician to make it rather than making it silently.

Interpretation uses three bands because the sources disagree. A total of 6 or less is unfavourable on both readings. A total above 8 is the range in which, per ACOG, the probability of vaginal delivery after induction is similar to spontaneous labour. Totals of 7 and 8 fall where ACOG's framing and other references part company, and are reported as their own band.

Worked through the example on this page: a dilation of 3 cm grades 2, an effacement of 60 percent grades 2, a station of −2 grades 1, a soft cervix grades 2, and a mid position grades 1. The total is 2 + 2 + 1 + 2 + 1 = 8, which lands in the disputed 7-to-8 band.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Bishop EH. Pelvic scoring for elective induction. Obstetrics and Gynecology. 1964;24:266–268. The original five-component score with a total of 0 to 13. (Publisher full text paywalled; consulted 2026-07-29. The component table used here comes from the reference below, which reproduces it.)
2. [2]Bishop Score. StatPearls, NCBI Bookshelf NBK470368. Source of the component table with point values implemented here, of the 0–13 range, and of the explicit statement that the score uses the −3 to +3 station system, "which differs from the modern ACOG scale of −5 to +5". (Full text retrieved 2026-07-29.)
3. [3]American College of Obstetricians and Gynecologists. Induction of Labor. ACOG Practice Bulletin No. 107, August 2009. Source of the band framing used on this page: an unfavourable cervix is "generally defined as a Bishop score of 6 or less in most randomized trials", and "if the total score is more than 8, the probability of vaginal delivery after labor induction is similar to spontaneous labor". (Retrieved 2026-07-29 from a hospital-hosted copy of the bulletin.)