SettingsSettings for this calculationUS
The standard allowance most suppliers and estimating guides assume for ordinary work.
The volume of lime mortar the joints or the wall take, before any waste.
Bring it across from a joint take-off rather than guessing it. For repointing, the Tuckpointing Mortar Repair Volume Calculator turns the length of joint, the width you cut to and the depth you rake to into a volume; for new work laid in lime, a brick or block calculator gives the mortar for the wall. As a sense of scale, 400 m (1,312 ft) of joint 10 mm (0.39 in) wide raked 25 mm (0.98 in) deep holds 100 litres (26.4 US gal).
The lime your specification names. The page batches it; it does not choose it.
NHL is a powder that sets partly with water and partly by taking carbon dioxide back from the air; the number is the binder's strength class under BS EN 459-1, measured on a laboratory mix, not the strength of your joint. Lime putty is slaked lime kept wet in a tub and sets only by carbonation, slowly. Dry bagged hydrated lime (ASTM C207 Type S or SA, or CL 90-S powder) is neither of these and has no yield rule here, so do not pick putty for it. Which one the wall wants is decided by the existing mortar and masonry and by whoever specifies the work.
Parts of damp, loose sand to one part of lime, by the bucket.
The page opens on 1 : 2½, the mix Saint-Astier gives for pointing medium to soft stone and brick in NHL 2 and NHL 3.5. Hanson's Castle putty is usually gauged at 2½ to 3 parts sand. Only these three ratios are offered because they are the ones the makers measured or stated a yield for; the ratio on your specification is the one to use.
What a loose volume of the NHL 3.5 powder weighs, from the maker's data sheet.
Saint-Astier gives 0.65 kg per litre as typical for its NHL 3.5, 650 kg/m³ (40.6 lb/ft³), inside the 0.45 to 0.75 kg per litre (28.1 to 46.8 lb/ft³) its sheet lists under BS EN 459. Makers differ: Hanson's bucket table for its NHL 3,5 works out nearer 0.56 to 0.60 kg per litre (35.0 to 37.5 lb/ft³). A lighter powder means more litres in each bag, so fewer bags for the same mortar.
The weight of dry sand in one volume of damp, loose sand, to turn the sand into an order.
ASTM C270 counts one cubic foot of damp, loose masonry sand as 80 lb of dry sand, 1,280 kg/m³, and the page opens there. It changes only the sand's weight, never its volume or the lime. A merchant who publishes a figure for their own sand is the better source, and their weight of damp sand runs higher than this dry figure by the water in it.
What one bag of the natural hydraulic lime holds, as printed on the bag.
Saint-Astier and Hanson pack NHL in 25 kg bags, and North American distributors sell the same bag labelled 55 lb (the exact figure is 55.1 lb), which is where an imperial reader opens. Not read when the lime is putty; the tub weight is used instead.
What one tub or bucket of the putty weighs, as the supplier sells it.
British putty is sold both by weight and by volume. Cornish Lime's tubs hold 10 kg (22 lb) or 25 kg (55 lb), and a metric reader opens on the 25 kg tub; Hanson's Castle putty comes in 17 litre (4.5 US gal) tubs, and for a tub sold by the litre enter its litres multiplied by the putty's density. An imperial reader opens on 58 lb (26.3 kg), the weight Lancaster Lime Works lists for its filled 5 gallon (18.9 litre) pail. That listing does not say whether the pail is included, and a full 5 gallons of putty at 80 lb/ft³ (1,280 kg/m³) would weigh about 53 lb (24.2 kg), so weigh the putty itself where you can. Not read when the lime is NHL; the bag weight is used instead.
Extra mortar for what is dropped, left on the spot board or stiffens before it is used.
The page opens at 10, a starting figure of its own and not a published rate. Pointing loses more than bedding, because every small batch leaves some in the bucket and on the hawk; set it from what your last comparable job actually used.
Lime to buy
2 bags
NHL 3.5 at 1 : 2½ by volume. The mortar is not the lime and the sand added together: in Hanson's measured mixes for its NHL 3,5, 7 buckets of 15 litres (4 US gal) of damp sand per 25 kg (55 lb) bag make 0.10 m³ (3.53 ft³), so at this ratio each volume of sand makes 0.95 of mortar, and the sand shown is the mortar divided by that. The lime, its grade and the ratio are the specification's to set; this page batches them and does not choose them.
- Mortar to make, waste included
- 27.5 gal
- Lime by volume
- 11.55 gal
- Lime by weight
- 62.65 lb
- Sand by volume, damp and loose
- 28.88 gal
- Sand by weight, dry
- 0.15 tons
- Lime and sand together, by weight
- 0.19 tons
- Mortar each bag or tub makes
- 24.14 gal
They open the calculator with your figures already in it
Lime Mortar Mix Calculator (NHL and Lime Putty): 2 bags — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- NHL yield: Hanson Natural Hydraulic Lime NHL 3,5 Technical Data Sheet (updated April 2020), standard mixes per 25 kg bag, measured with heavy-duty 15 litre buckets of sand at 7% moisture: 6, 7 and 9 buckets of sand at 1 : 2, 1 : 2½ and 1 : 3 make 0.09, 0.10 and 0.12 m³ of mortar, so a volume of sand makes 1.00, 0.95 and 0.89 of its own volume in mortar. The same sheet gives the working temperatures and says mortar should in general be weaker than the masonry it is used with
- Putty yield: Hanson Castle Lime Putty technical data sheet (L006(Hc)/08/09), BS EN 459-1 CL 90: proportioned with 2½ to 3 parts sand by volume, the putty fills the spaces between the sand particles without adding to the overall volume, so the coarse stuff equals the volume of sand used. Bulk density 1,220 to 1,320 kg/m³; sold in 17 litre tubs
- NHL 3.5 density and the default ratio: Saint-Astier NHL 3.5 technical data sheet (édition Décembre 2023, 23346): bulk density 0.45 to 0.75 kg/l under BS EN 459, typical 0.65 kg/l; 25 kg bag; pointing medium to soft natural stone and brick at 1 NHL 3.5 to 2.5 sand; not below 8 °C or above 30 °C, wet mortar protected from frost for at least 10 days
- NHL 2 density: Saint-Astier NHL 2 technical data sheet (édition Décembre 2023, 23346): bulk density 0.4 to 0.7 kg/l under BS EN 459, typical 0.5 kg/l; 25 kg bag; pointing medium to soft stone and brick at 1 NHL 2 to 2.5 sand
- NHL 5 density and the North American bag: Saint-Astier NHL 5 technical data sheet, US distributor edition (édition Octobre 2024, 24277): bulk density 0.5 to 0.8 kg/l under NF EN 459, typical 0.7 kg/l (43.7 lb/ft³); packed as a 25 kg bag labelled 55 lb
- Sand, putty and hydrate densities, and what the mortar types contain: ASTM C270-19a, Standard Specification for Mortar for Unit Masonry, 6.1.1 and Note 9: lime putty 80 pcf (1,280 kg/m³); hydrated lime 40 pcf (640 kg/m³); sand 80 pcf, the weight of dry sand in one cubic foot of damp, loose sand. Aggregate is measured damp and loose. Section 5.1 permits each of Types M, S, N and O as a cement-lime, mortar cement or masonry cement mortar, and Table 2's cement-lime Type O carries over 1¼ to 2½ parts hydrated lime per part of portland cement
- US putty bucket and a caution on fixed ratios: Lancaster Lime Works, Architectural Lime Putty, 5 gallon bucket, listed weight 58 lb (product listing, which does not say whether the pail is included); and Proper Ratio of Lime to Sand (16 April 2022): the putty must fill the void space within the sand, the right proportion varies from sand to sand and load to load and is found by testing the sand's voids, and specifications calling for fixed ratios such as 1:2 or 1:3 are described as misleading
- UK putty tub: Cornish Lime, Mature Lime Putty (product listing): 10 kg and 25 kg tubs, approximate bulk density 1,350 kg/m³, usually mixed at 1 : 3 or 2 : 5
- Who decides the mortar: NPS Preservation Brief 2, Repointing Mortar Joints in Historic Masonry Buildings (Robert C. Mack and John P. Speweik, October 1998): the new mortar must be as vapor permeable as, and as soft or softer than, the historic mortar; for repointing, hydrated lime should conform to ASTM C 207, Type S or Type SA
- Dry hydrated lime: National Lime Association, Fact Sheet: Hydrated Lime for Masonry Purposes (June 2002): ASTM C207 Type S and SA, approximate bulk density 40 lb/ft³, packed in 50 lb (22.7 kg) bags
Inputs used
- Mortar needed
- 25 gal
- Lime
- NHL 3.5 natural hydraulic lime
- Mix ratio, lime to sand by volume
- 1 : 2½
- NHL 2 bulk density
- 31.21 pcf
- NHL 3.5 bulk density
- 40.58 pcf
- NHL 5 bulk density
- 43.7 pcf
- Lime putty density
- 79.91 pcf
- Sand bulk density, dry weight in damp loose volume
- 79.91 pcf
- NHL bag weight
- 55 lb
- Lime putty tub weight
- 58 lb
- Waste allowance (%)
- 10
Intermediate steps
- Mortar to make, waste included
- 27.5 gal
- Lime by volume
- 11.55 gal
- Lime by weight
- 62.65 lb
- Sand by volume, damp and loose
- 28.88 gal
- Sand by weight, dry
- 0.15 tons
- Lime and sand together, by weight
- 0.19 tons
- Mortar each bag or tub makes
- 24.14 gal
Confidence note: NHL 3.5 at 1 : 2½ by volume. The mortar is not the lime and the sand added together: in Hanson's measured mixes for its NHL 3,5, 7 buckets of 15 litres (4 US gal) of damp sand per 25 kg (55 lb) bag make 0.10 m³ (3.53 ft³), so at this ratio each volume of sand makes 0.95 of mortar, and the sand shown is the mortar divided by that. The lime, its grade and the ratio are the specification's to set; this page batches them and does not choose them.
What this calculation does not cover
- The NHL yield is Hanson's measured table for its own NHL 3,5, gauged with damp sand in heavy-duty 15 litre (4 US gal) buckets at about 7% moisture, and the page applies it to NHL 2 and NHL 5 as well. Another maker's lime, a sharper or rounder sand, or a drier or wetter heap will make a little more or less mortar per bag; a trial batch measured in the barrow settles it for your materials.
- Only 1 : 2, 1 : 2½ and 1 : 3 by volume are offered, because those are the mixes the two yield statements cover. A specification written as 1 : 1½, as a weight ratio, or as a gauged mix with a pozzolan or a little cement added sits outside the rule this page uses and is not batched here. Lancaster Lime Works argues that a putty proportion should come from measuring the void space in the actual sand rather than from a fixed ratio; where that test gives a proportion other than these three, this page cannot batch it.
- Sand is measured damp and loose, the way it is gauged on site, and its weight is shown dry, at the density entered: ASTM C270 takes 80 lb of dry sand to a cubic foot of damp loose sand, 1,280 kg/m³. A merchant's weight of damp sand includes its water and reads higher, and dry sand gauged by the bucket packs more grains into each measure than damp sand does.
- Nothing here selects the lime, the grade, the ratio or the sand. The mortar should be weaker and more vapour-permeable than the brick or stone it joins, and on a listed or historic building the conservation officer, the surveyor or the written specification decides what goes in the joint, usually after the old mortar has been examined.
- Curing is outside the arithmetic: protection from frost, sun and wind, damping down, and how long a batch stays workable are set by the lime's maker. Saint-Astier's sheets say not below 8 °C (46 °F) or above 30 °C (86 °F), with frost kept off for at least 10 days; Hanson's NHL 3,5 sheet gives 5 °C (41 °F) to 30 °C (86 °F). Read the sheet for the lime you buy.
- Premixed lime mortar, bagged dry or delivered as ready-to-use coarse stuff, and hot-mixed lime made from quicklime on site are not covered; buy those by the maker's own yield per bag or tonne. Mixing water is not counted either, and putty's weight already includes the water it is stored in.
- Dry bagged hydrated lime is not batched here: ASTM C207 Type S or SA, sold in the US in 50 lb (22.7 kg) sacks, or CL 90-S powder in the UK. Neither yield statement this page uses covers a dry hydrate, and ASTM C270 weighs it at 640 kg/m³ (40 lb/ft³), half of putty's figure, so batching it here as lime putty roughly doubles the weight of lime the page gives. Do not enter it as putty; take its yield from the maker's sheet or a measured trial batch.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Part of a bigger job
This trade is one line of a job takeoff. Run the whole job and every other trade comes back with it, off the same measurements.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-28 · v1.0.0
Regulatory standards & verification citations10
- NHL yield: Hanson Natural Hydraulic Lime NHL 3,5 Technical Data Sheet (updated April 2020), standard mixes per 25 kg bag, measured with heavy-duty 15 litre buckets of sand at 7% moisture: 6, 7 and 9 buckets of sand at 1 : 2, 1 : 2½ and 1 : 3 make 0.09, 0.10 and 0.12 m³ of mortar, so a volume of sand makes 1.00, 0.95 and 0.89 of its own volume in mortar. The same sheet gives the working temperatures and says mortar should in general be weaker than the masonry it is used with
- Putty yield: Hanson Castle Lime Putty technical data sheet (L006(Hc)/08/09), BS EN 459-1 CL 90: proportioned with 2½ to 3 parts sand by volume, the putty fills the spaces between the sand particles without adding to the overall volume, so the coarse stuff equals the volume of sand used. Bulk density 1,220 to 1,320 kg/m³; sold in 17 litre tubs
- NHL 3.5 density and the default ratio: Saint-Astier NHL 3.5 technical data sheet (édition Décembre 2023, 23346): bulk density 0.45 to 0.75 kg/l under BS EN 459, typical 0.65 kg/l; 25 kg bag; pointing medium to soft natural stone and brick at 1 NHL 3.5 to 2.5 sand; not below 8 °C or above 30 °C, wet mortar protected from frost for at least 10 days
- NHL 2 density: Saint-Astier NHL 2 technical data sheet (édition Décembre 2023, 23346): bulk density 0.4 to 0.7 kg/l under BS EN 459, typical 0.5 kg/l; 25 kg bag; pointing medium to soft stone and brick at 1 NHL 2 to 2.5 sand
- NHL 5 density and the North American bag: Saint-Astier NHL 5 technical data sheet, US distributor edition (édition Octobre 2024, 24277): bulk density 0.5 to 0.8 kg/l under NF EN 459, typical 0.7 kg/l (43.7 lb/ft³); packed as a 25 kg bag labelled 55 lb
- Sand, putty and hydrate densities, and what the mortar types contain: ASTM C270-19a, Standard Specification for Mortar for Unit Masonry, 6.1.1 and Note 9: lime putty 80 pcf (1,280 kg/m³); hydrated lime 40 pcf (640 kg/m³); sand 80 pcf, the weight of dry sand in one cubic foot of damp, loose sand. Aggregate is measured damp and loose. Section 5.1 permits each of Types M, S, N and O as a cement-lime, mortar cement or masonry cement mortar, and Table 2's cement-lime Type O carries over 1¼ to 2½ parts hydrated lime per part of portland cement
- US putty bucket and a caution on fixed ratios: Lancaster Lime Works, Architectural Lime Putty, 5 gallon bucket, listed weight 58 lb (product listing, which does not say whether the pail is included); and Proper Ratio of Lime to Sand (16 April 2022): the putty must fill the void space within the sand, the right proportion varies from sand to sand and load to load and is found by testing the sand's voids, and specifications calling for fixed ratios such as 1:2 or 1:3 are described as misleading
- UK putty tub: Cornish Lime, Mature Lime Putty (product listing): 10 kg and 25 kg tubs, approximate bulk density 1,350 kg/m³, usually mixed at 1 : 3 or 2 : 5
- Who decides the mortar: NPS Preservation Brief 2, Repointing Mortar Joints in Historic Masonry Buildings (Robert C. Mack and John P. Speweik, October 1998): the new mortar must be as vapor permeable as, and as soft or softer than, the historic mortar; for repointing, hydrated lime should conform to ASTM C 207, Type S or Type SA
- Dry hydrated lime: National Lime Association, Fact Sheet: Hydrated Lime for Masonry Purposes (June 2002): ASTM C207 Type S and SA, approximate bulk density 40 lb/ft³, packed in 50 lb (22.7 kg) bags
Which documents these citations point at
Standards referenced: BS EN 459-1, BS EN 459 (European Committee for Standardization, as published in the UK by BSI, European (EN)); ASTM C270-19, ASTM C207 (ASTM International, United States).
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Your workspace
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Tools and safety for this job
To mix mortar. Generic types, no brands, no prices.
Protection this work requires
- Cutting or grinding concrete, masonry, screed, tile or fibre-cement board releases respirable silica: cut wet or extract at the tool, and wear a P2/N95 respirator at minimum — a nuisance dust mask does not filter it.
- Wet cement and lime burn skin and eyes painlessly until the damage is done: waterproof gloves to EN 374, safety glasses whenever the mix can splash, and never kneel in wet mix in permeable trousers.
Show the 4 tools this job needsHide tools
Essential
Shovel and spade
Wheelbarrow
Recommended
Cement mixer
Mixing bucket or tub
what each masonry tool is for, and the spec that decides which to buy where one does.