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Casio F-91W strap size: 18 mm lug width

The Casio F-91W takes an 18 mm strap: its lug width is 18 mm, fitted with pins rather than standard spring bars. The case is 35.2 mm wide, 38.2 mm long (case length L, not lug to lug), and 8.5 mm thick. Strap length for your wrist: the strap size tool.

Sources checked · How we source numbers
Width (W)
35.2 mm3
Case length (L)
38.2 mm3
not lug to lug
Thickness
8.5 mm3
Lug width
18 mm4
Casio F-91W, front view
Photo: Ashley Pomeroy, CC BY-SA 3.0, via Wikimedia Commons
Casio F-91W: size drawingCasio F-91W, rect case, top and side view to scale: case width 35.2 mm, case length (Casio L) 38.2 mm, lug width 18 mm, thickness 8.5 mm. Bezel, dial and crown size are schematic.lug width 18width 35.2case length (Casio L) 38.2TOPthickness 8.5SIDE
Casio F-91W, top and side, to scaleDrawing from data, not a photo · mm

Casio F-91W strap size

Lug width 18 mm4seller listing: an 18 mm band fits between the lugs, held by pins rather than spring bars. 8 other models take 18 mm.

Attachment: pin7.

Casio describes pins here, not standard spring bars. Check a replacement band against this model's pin fitting as well as its measured width.

Find your strap length in the watch strap size tool, with the Casio F-91W filled in.

18 mm strap: strap diagramTwo-piece strap laid flat (18 mm strap). Lug width 18 mm. Short piece — (unknown), long piece — (unknown). Buckle, keepers and holes are schematic.short —long —lug 18lug 18strap length —18 mm strap
18 mm at the lugs; lengths depend on your wristDrawing from data, not a photo · mm

Module 593 twins

Casio's manual list puts 13 model codes on this module: same functions, same manual, often the same battery.

Codes of the Casio F-91W family[8]F-91W, F-91WB, F-91WF, F-91WM, F-91WPC, F-91WS

Other families on it with a page here

1 more codes on the same module

A171WE

Casio module 593: functions, battery and manual

Module: Casio module 593

The Casio F-91W runs on the Casio module 593, a digital module. 2 other models in our base use it.

Power source
battery2
Battery life
7 years2
Accuracy
±30 s/month2

Battery

Casio F-91W specifications

Case width (W)
35.2 mm3
Lug to lug
not published by Casio; see case length (L)
Case length (L)
38.2 mm3Casio's L of L × W × H, measured differently from lug to lug; we never swap one for the other.
Thickness (H)
8.5 mm3
Lug width
18 mm4seller listing18 mm watches
Weight
21 g3
Crystal
Resin Glass3
Water resistance
Water Resistant3
3 sources disagree; show every value
  • manufacturer Water Resistant3
  • secondary source Water Resist1
  • secondary source 30 meter / 3 bar1
Module
Casio module 5938 · digital moduleCasio module 593 specs
Battery
Accuracy
±30 s/month3
Years made
19893
Case code
not used by Casio: the module number (module 593) identifies the watch
Strap attachment
pin7
Band fits
145–200 mm wrist3

On your wrist

The verdict compares the case length (L) with the flat top of your wrist. Balanced from ~13.5 cm, past the edges below ~12 cm.

= 6.7 in

Compact on a 17 cm wrist: the 38.2 mm case length (L) covers 70% of an estimated 54.8 mm flat top.

Casio publishes no lug-to-lug for this model, so the verdict uses its case length (L). The strap or bracelet joins inside that length, which makes this a cautious estimate.

Casio cuts the band for wrists of 14.5–20 cm: your wrist is inside that range.

Flat top = circumference ÷ 3.1, a community convention, not a measurement of your arm. Compact ≤ 0.75 of the flat top, balanced ≤ 0.89, at the edge ≤ 1. Compare more watches in the watch size calculator.

Casio F-91W: wrist fitCasio F-91W on a wrist, top view to scale. case length (Casio L) 38.2 mm. Wrist 170 mm, estimated flat width 54.8 mm (circumference / 3.1). Ratio 0.70: compact.wrist, flat topwrist flat ≈ 54.8case length (Casio L) 38.2Compact · 38.2 / 54.8 = 0.70estimate: wrist 170 / 3.1 = 54.8 flatcompactbalancededgeoverhang0.750.891
Casio F-91W on a 17 cm wristDrawing from data, not a photo · mm

Actual size on your screen

Calibrate once with a bank card and the drawing shows the Casio F-91W at 1:1, next to a millimetre ruler.

1:1 · not calibrated: sizes are approximate
Casio F-91W: size drawingCasio F-91W, rect case, top and side view to scale: case width 35.2 mm, case length (Casio L) 38.2 mm, lug width 18 mm, thickness 8.5 mm. Bezel, dial and crown size are schematic.lug width 18width 35.2case length (Casio L) 38.2TOPthickness 8.5SIDE
Drawing from data, not a photo · mm
01020304050

Same size as the Casio F-91W

The models nearest to the Casio F-91W in case width and case length (L), drawn over it to scale; below, every model within 1 mm of its 38.2 mm.

Size comparison: Casio F-91W, Casio LW-200, Casio MQ-24, Casio LW-204Top-view outlines to scale on one centre. A Casio F-91W: W 35.2, L 38.2, lug 18, T 8.5. B Casio LW-200: Ø 34.9, L 37.9, lug —, T 11.9 (vs A: W −0.3 L −0.3 T +3.4). C Casio MQ-24: Ø 34.9, L 38.8, lug 16, T 7.8 (vs A: W −0.3 L +0.6 lug −2 T −0.7). D Casio LW-204: Ø 35, L 38.9, lug —, T 9.4 (vs A: W −0.2 L +0.7 T +0.9).B Ø 34.9C Ø 34.9D Ø 35A W 35.2B L 37.9A L 38.2C L 38.8D L 38.9A Casio F-91WW 35.2 · L 38.2 · lug 18 · T 8.5B Casio LW-200Ø 34.9 · L 37.9 · lug — · T 11.9vs A: W −0.3 L −0.3 T +3.4C Casio MQ-24Ø 34.9 · L 38.8 · lug 16 · T 7.8vs A: W −0.3 L +0.6 lug −2 T −0.7D Casio LW-204Ø 35 · L 38.9 · lug — · T 9.4vs A: W −0.2 L +0.7 T +0.9
A Casio F-91W and the 3 nearest in size, on one centre, to scaleDrawing from data, not a photo · mm

Nearest in size

  1. ACasio F-91Wthis watch
  2. BCasio LW-200W −0.3 · L −0.3 · T +3.4 mm
  3. CCasio MQ-24W −0.3 · L +0.6 · T −0.7 mm
  4. DCasio LW-204W −0.2 · L +0.7 · T +0.9 mm

Differences against A in mm: W case width, L Casio case length, T thickness. Nearest by width and length together, from the published sizes.

Same movement: Casio module 593

Casio F-91W questions

What strap size does the Casio F-91W take?

The Casio F-91W measures 18 mm between the lugs, so it takes an 18 mm band held by pins rather than standard spring bars; check the replacement fitting. 8 other models in our base share that width.

Find the strap length for your wrist and the Casio F-91W in the watch strap size tool.

Where is the manual for the Casio F-91W?

The Casio F-91W runs Casio module 593, and Casio publishes the operation guide for that module as a PDF: Casio operation guide 593. The module number is stamped on the case back. All of the module’s models and its battery are on its page.

What battery does the Casio F-91W take?

The Casio F-91W takes CR2016, rated about 7 years.

How big is the Casio F-91W?

The Casio F-91W measures 35.2 mm wide, 38.2 mm long (Casio's L, not lug to lug), 8.5 mm thick, 21 g.

Will the Casio F-91W fit a 5.5-inch wrist?

Balanced: the Casio F-91W's 38.2 mm case length (L) takes 85% of the ~45.1 mm flat top of a 5.5-inch (14.0 cm) wrist. By the same estimate (circumference ÷ 3.1) it sits balanced from about 13.5 cm and overhangs the flat top on wrists under about 12 cm.

What module is in the Casio F-91W?

The Casio F-91W runs on the Casio module 593, a digital module. Casio's manual list puts 13 model codes on this module, 6 of them F-91W codes.

More Casio watches

Sources

Documents checked · Report a wrong number

  1. 1Wikipedia (CC BY-SA 4.0) — Casio F-91W · html · read
  2. 2Casio Computer Co., Ltd. — Operation Guide 10B+7L(Ver.C), manual for module 593 (qw593_EN.pdf) · pdf · read
  3. 3Casio America — F91W-1 | Casio Classic Digital Watch (product page) · html · read
  4. 4StrapsCo — Classic Rubber Strap For Casio F-91W · html · read
  5. 5VARIO — Top Grain Coal Black Leather Watch Strap with Red Stitching for Casio F91W & Timex Q · html · read
  6. 6StrapHabit — Casio F91W vs. A158 Watch Review. What's the Difference? · html · read
  7. 7Casio — F-91W series · html · read
  8. 8Casio Computer Co., Ltd. — Watch manual search JSON (US locale), manual_search.support.json · json · read