Quantity (FIX tag 53)

QtyFIX 4.4FIX 4.2FIX 5.0 SP2

Quantity (tag 53) is a Qty field defined in FIX 4.4, FIX 4.2 and FIX 5.0 SP2. It appears in 9 message types and is required in 3 of them. FIX 4.2 calls this field Shares; the tag number is unchanged, so the two are the same field on the wire.

Also known as Shares

FIX 4.2 calls tag 53 Shares. It is the same field on the wire — only the name changed — so a message encoded by either side interoperates.

At a glance

Tag: 53
Name: Quantity
Datatype: Qty (float)
Dialects: FIX 4.4, FIX 4.2 and FIX 5.0 SP2
Messages: 9

What the specification says

FIX 4.4

Overall/total quantity (e.g. number of shares) (Prior to FIX 4.2 this field was of type int)

FIX 4.2

Number of shares (Prior to FIX 4.2 this field was of type int)

FIX 5.0 SP2

Overall/total quantity (e.g. number of shares)

Descriptions are quoted from the FIX Orchestra sources under the Apache 2.0 licence.

A real message using tag 53

AllocationInstruction · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	129
35	MsgType	J	Allocation Instruction
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
70	AllocID	EXAMPLE
71	AllocTransType	0	New
626	AllocType	1	Calculated (includes MiscFees and NetMoney)
857	AllocNoOrdersType	0	Not specified
54	Side	1	Buy
53	Quantity	1000000
6	AvgPx	1.09215
75	TradeDate	20240101
10	CheckSum	120

Edit and decode it yourself

Shown with | separators for readability. On the wire FIX uses SOH (0x01), an invisible control byte — and because BodyLength and CheckSum are computed over the actual bytes, the two forms have different checksums. Both are valid and both decode here.

Open in the full decoder →

Generated from the FIX 4.4 dictionary and verified at build time: it parses and validates with no issues. Open the decoder to try your own message.

Where tag 53 appears

Requiredness is a property of the message, not of the field: the same tag can be optional in one message and conditionally required in another.

Message	MsgType	FIX 4.4	FIX 4.2	FIX 5.0 SP2	Where in the message
Advertisement	7	Required	Required	Required	directly on the message body
AllocationInstruction	J	Required	Required	Required	directly on the message body
AllocationInstructionAlert	BM	—	—	Required	directly on the message body
AllocationReport	AS	Required	—	Required	directly on the message body
AllocationReportAck	AT	—	—	Optional	directly on the message body
CollateralAssignment	AY	Optional	—	Optional	directly on the message body
CollateralInquiry	BB	Optional	—	Optional	directly on the message body
CollateralInquiryAck	BG	Optional	—	Optional	directly on the message body
CollateralReport	BA	Optional	—	Optional	directly on the message body
CollateralRequest	AX	Optional	—	Optional	directly on the message body
CollateralResponse	AZ	Optional	—	Optional	directly on the message body

Wire format

A decimal quantity. Fractional quantities are legal, which is why this is a float family rather than an integer. @boarteam/fix parses the value as a number and reports parse/invalid-float when it does not lex as one; the raw string is kept so precision and trailing zeros are never lost.

Read tag 53 in TypeScript

decode.tsts

import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix44";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const field = message.fields[53];field?.name;   // "Quantity"field?.raw;    // the verbatim wire stringfield?.value;  // coerced to a number

Decode this in your own code

The same engine that produced the decoded example above is an Apache-2.0 npm package with zero runtime dependencies. It runs in Node and in the browser, and parse() returns problems as data instead of throwing.

npm i @boarteam/fix @boarteam/fix-dict-fix44

Try the decoder Source on GitHub